European Journal of
Europ. J. Pediat. 125, 59--70 (1977)
Pediatrics 9 by Springer-Verlag 1977
Juvenile Familial Hypertriglyceridemia and Growth Retardation Clinical and Biochemical Observations in Three Siblings
Hans J. Sternowsky I, U. Gaertner*, N. Stahnke 1, and E. Kaukel 2 ~Department of Paediatrics, Martinistrage 52, D-2000 Hamburg 20, Federal Republic of Germany, and 2Department of Internal Medicine, University Hospital Hamburg-Eppendorf, University of Hamburg, Martinistral~e 52, D-2000 Hamburg 20, Federal Republic of Germany
Abstract. Familial hypertriglyceridemia or hyperlipoproteinemia type I was detected in three siblings aged 6, 11, and 14 of an otherwise normal Turkish family of 10 members. Initial values ranged from 1780 to 3750 mg/100 ml triglycerides in the milky white serum; cholesterol was normal. Lipoprotein pattern on agarose and acrylamide gel revealed a heavy band of chylomicrons and missing HDL; post-heparin lipolytic activity was decreased to about 30% of normal. Chylomicronemia could be induced by a fat-rich (50% of total calories) diet, but not by carbohydrates. On a low fat diet (5%) during hospitalization chylomicrons disappeared, and triglycerides decreased to about 450mg/100ml. Phenocopies of hypertriglyceridemia could be excluded. All three patients were the only members of the family who were small, below the third percentile. Their bone age was retarded from 18 to 30 months. There was no indication for an endocrine cause of the growth retardation: four different stimulation tests revealed normal growth hormone response, thyroid and adrenal functions were not impaired; sexual development was normal. Increased glucose assimilation was observed during intravenous and oral glucose load. Peak serum insulin response was above normal during stimulation tests. The possible etiologic role of hypertriglyceridemia in this concomitant growth retardation is discussed. Key words: Hypertriclyceridemia - Hyperlipoproteinemia - Growth retardation.
Zusammenfassung. Bei drei Kindern, 6, 11 und 14 Jahre, einer sonst nicht auff~illigen ttirkisehen zehnk6pfigen Familie wurde eine Hyperlipoprotein~imie Typ I nach Frederickson gefunden. Initial betrugen die Triglyceridwerte des milchig-weiBen Serums 1780 bis 3750 mg/dl, Serum-Cholesterin war nicht erhOht. In der Lipoproteinelektrophorese auf Agarose- und Acrylamidgel * P r e s e n t A d d r e s s : University of Konstanz, Department of Biology, D-7750 Konstanz, Federal Republic of Germany
60
H.J. Sternowsky et al. stellten sich eine ausgeprggte Bande der Chylomikronen, jedoch keine der H D L dar, die post-heparin lipolytische Aktivit~it war auf 30% der Norm erniedrigt. Bei fettreicher (50% der Gesamtkalorien) Kost konnten Chylomikronen induziert werden, Kohlenhydrate hatten diesen Effekt nicht. Bei fettarmer (5%) Kost verschwanden die Chylomikronen w~thrend der station~tren Behandlung, die Triglyceridwerte fielen auf etwa 450 mg/dl. Anhalt ftir Ph~tnokopien wurde nicht gefunden. Als einzige Familienmitglieder waren alte drei Patienten zu klein, die Kt~rpergrrBe lag bei allen unter der dritten Perzentile. Wiederum hatten nur die Patienten ein retardiertes Knochenalter, minus 18 bis 30 Monate. Es fand sich jedoch kein Hinweis ftir eine endokrinologische Ursache der Wachstumsverz6gerung: Bei 4 verschiedenen Stimulationstests normaler Anstieg des Serum-STH, Schilddrtisen- und Nebennierenrindenfunktionen waren unbeeintr~ichtigt, die Sexualentwicklung war altersentsprechend. W~thrend der intraven/Ssen und der oralen Glukosebelastung wurde eine erhrhte Glukoseassimilation gefunden. Jedoch waren die Serum-Insulinwerte w~ihrend dieser Stimulationstest im Normbereich. Die M6glichkeit, dab die angeborene Hypertriglycerid~imie eine kausale Rolle bei der Entstehung der Wachstumsverz6gerung spielt, mug diskutiert werden.
Introduction
Familial hypertriglyceridemia is a rare disorder of fat metabolism. It was named familial type I hyperlipoproteinemia by Frederickson et al. (1967). It is defined by a genetically determined increase in the plasma concentration of chylomicrons. A slight decrease in low-density lipoproteins (LDL) and high-density lipoproteins (HDL) may occur. Plasma cholesterol levels are normal or moderately increased, the cholesterol versus triglyceride quotient is smaller than 0.2 (Frederickson and Breslow, 1973; Jones, 1973; Glueck et al., 1964). These values are found in patients on unrestricted diet. About 18% of the more than 60 cases reported up to date (May, 1976) were detected in childhood and infancy (Ditschuneit et al., 1972; Havel and Gordon, 1961; Braunsteiner et al., 1968; Dtichting, 1974; Ferrans et al., 1973; Frederickson and Breslow, 1973; Berger et al., 1962), usually because of eruptive xanthoma, abdominal pain, enlarged liver and spleen, and lipemia retinalis. One of the most obvious findings is that the plasma, after standing for 12 h at 4~ develops a chylomicron-composed, creamlike upper layer, whereas the infranate becomes clear. A diet low in fat (less than 15% of total calories) and high in proteins and carbohydrates causes the chylomicrons to disappear or decrease considerably, corresponding to a decrease of the triglyceride and cholesterol levels. Its pathogenetic mechanisms are not well known. Supposedly there is a defect in the potential to remove chylomicrons from the blood: the lipolytic activity is decreased. The enzyme responsible for this extracellular lipolysis is lipoprotein lipase, one of several triglyceride lipases found in human blood (Frederickson et al., 1967; Frederickson and Levy,1972). It hydrolyzes the ester bonds of chylomicrons and is activated by heparin, but not by epinephrine (Glueck et al., 1969).
Juvenile Familial Hypertriglyceridemia
61
Protamine, sodium pyrophosphate, and high concentrations of sodium chloride a r e p o t e n t i n h i b i t o r s o f this e n z y m e . T h e r e is n o r e p o r t o n h y p e r t r i g l y c e r i d e m i a d u r i n g c h i l d h o o d w h e r e r e t a r d e d g r o w t h was a n essential p a r t o f t h e clinical observations. In this respect a n d in v i e w o f the r a r i t y o f the disease, t o g e t h e r w i t h t h e f a c t t h a t its p a t h o g e n e s i s r e m a i n s o b s c u r e , we r e p o r t t h r e e cases o f a f a m i l y w i t h e i g h t c h i l d r e n , w h o c a m e to o u r a t t e n t i o n w h e n t h e y w e r e a d m i t t e d f o r s e v e r e scabies infestation.
Case Reports The three patients are from a Turkish family. They reported to the hospital with severe secondary infections of almost the whole body following scabies infestation. There were eight children, six of whom suffered from scabies; the parents and the two eldest siblings were not affected. On routine blood determinations lipemic sera were found and further metabolic investigations were initiated. Patient 1. O. G. was the youngest child, aged 5 years and 3 months when he was first admitted. He was the eighth child of the unrelated and apparently healthy parents. Pregnancy and birth as well as postnatal development were normal. He had never previously been hospitalized until admission for severe superinfeeted scabies with high temperature, general edema, and enlarged axillary and inguinal lymph nodes. The liver was 6 cm below the costal margin, the spleen 5 cm. The abdomen was distended, but the child did not complain of abdominal pain. Triglycerides were 2600mg/lOOml and total cholesterol was repeatedly normal. Lipemia retinalis was diagnosed during ophthalmologic examination. Patient 2. G. G. was 11 years old on admission for superinfected scabies. She had never been under medical care before. Pregnancy, birth, and postnatal development were normal. She had signs of acute inflammation similar to her brother, patient i. The liver was enlarged by 3 cm; the spleen was not palpable. She complained of upper intestinal pain and had mild diarrhea. Alphas-amylases were normal in urine and serum. After 2 days of treatment for gastrointestinal infection there were no more complaints. Serum triglycerides were increased to 3750 mg/100 ml; cholesterol was repeatedly normal. She too had lipemia retinalis. Patient 3. After the admission of these two patients the whole family was examined for triglyceride and cholesterol levels as well as height and bone age. One more affected child was found: He was an apparently healthy boy of 14 years and 9 months. There were no signs of inflammation, and the liver and spleen were not enlarged. Triglycerides were increased to 1780 mg/100 ml; cholesterol was normal. Again lipemia retinalis was found.
Additional measurements of endocrinologic status were performed in all three patients. The height and weight measurements are referred to standard charts indicating the percentile for chronological age (Tanner et al., 1966); height measurements are also presented as standard deviation scores (SDS) (Vince and Tanner, 1972). As an index of skeletal proportions the ratio of upper segment (US) to lower segment (LS) was determined and compared to normal standards (McKusick, 1966). Skeletal maturity was estimated from roentgenograms of the left hand and wrist by comparison with a standard atlas (Greulich and Pyle, 1959). The development of puberty was assessed by comparison with genital development changes during puberty (Tanner, 1969). The size of the testes was assessed by palpation in comparison with models of testicular shape (Prader orchidometer) of known volume (Prader, 1971). Patient 1. Bone maturation showed 2 years retardation; height was I5.5 cm below the third percentile; SDS --2.83, US : LS 1.143 (more than two SD above mean for age); weight was
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H . J . Sternowsky et al.
Fig. 1. Three siblings with familial hypertriglyceridemia and short stature: aged 5, 11, and 15 years
slightly above the third percentile for chronological age and between the 25th and 50th percentile for height age. Head circumference 50 cm, testis volume 1 ml. Patient 2. Bone age retarded 1.5 years; height - - 11.5 cm, between tenth and third percentile; SDS - - 1.595; US : LS 1.029 (more than two SD above mean for age); weight between 10th and 25th percentile for chronological age and between 50th and 75th percentile for height age. Head circumference 50.5 cm, breast development B 4, pubic hair P 2, axillary hair beginning. Patient 3. Bone age retarded 2 years; height --17.3 cm, below the third percentile; SDS --2.595; US : LS 1.010 (more than two SD above mean for age); weight between the 10th and 25th percentile for chronological age and slightly above the 75th percentile for height age. Head circumference 54 cm, pubic hair P 5, testis volume 20 ml, axillary hair +++.
The pedigree reveals three affected children with triglyceride levels exceeding the 99th percentile (Glueck et al., 1974), adjusted for age. All other members of this family of 10 had normal triglyceride levels. Including the patients just described every member of the family had normal cholesterol values when adjusted for age (Goldstein et al., 1973).
Juvenile Familial Hypertriglyceridemia
63
We were not able to study the grandparents of our patients. They are reported to have succumbed to endemic infection, seemingly unrelated to hyperlipemic symptoms. Thus we have to assume horizontal manifestation of hypertriglyceridemia in 37,5% of the offspring. The lipoprotein pattern on lipoprotein eleetrophoresis on acetate foil was normal in the mother and five siblings. The father had an increase in pre-fl-lipoproteins to 55.1%. There were no clinical signs of diabetes, hypothyroidism, nephrotic disease or hyperuricemia. He was 35 years of age and 23% overweight for height. The height of the father and the unaffected children was normal, between the 50th and 75th percentile. The mother, however, was 149 cm tall, thus below the third percentile. She reported that her parents, too, were of small stature, and that her first menstrual bleeding was at age 13. Bone age in all unaffected members of the family was not retarded and did not show deviations of more than 3 months from the chronological age.
Results of Special Studies
a) Lipoproteins Massive c h y l o m i c r o n e m i a was demonstrated by leaving the lactescent plasma, taken after a fasting period of 14 hours, overnight at 4~ Chylomicrons rose to the top to f o r m a creamy layer; the infranate remained clear. Lipoprotein electrophoresis on cellulose acetate foil (Grabner, 1970) was performed in all three patients once a week during the course of the clinical evaluation. Initially the pattern for chylomicron-rich plasma and the clear infranate were determined (Table 1). In the lactescent plasma, alpha-lipoproteins could never be d e m o n strated, chylomicrons were not present in the infranate, and fl-lipoproteins were decreased in all three patients. The additional lipoprotein electrophoresis on polyacrylamid gel gave confirming results. Initially the patients were kept on a regular diet of their choice. The diet was analyzed once and then kept constant as far as calories, percentage of fat, quality of fat, percentage of carbohydrates and percentage of protein were concerned (Table 2, diet I). The ratio of saturated over unsaturated and highly unsaturated fatty acids reflects the n o r m a l composition of fat intake in this country (Stroink, 1967) with 39% saturated and 61% unsaturated fat. Following the initial phase of two weeks, three feeding studies were performed, each lasting 7 days. The diets were fat-rich (II), carbohydrate-rich (Ill) and low in fat (IV). The f o r m a t i o n of chylomicrons and triglycerides was f o u n d to be influenced by the fat-rich diet (Table 3), but not by the carbohydrate-rich diet. D u r i n g the fat-rich regimen cholesterol values were increased moderately. The fractionation
Table 1. Lipoprotein electrophoresis (values given in %) of the initially found serum without dietary measures Lactescent serum
Patient 1 Patient 2 Patient 3
Chylo
pre-beta beta
alpha
64.0 74.2 76.5
28.1 11.4 13.1
0 0 0
7.9 14.4 10.4
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H.J. Sternowsky et al.
Table 2. Composition of diets during clinical investigation (in % of total calories)
Diet Diet Diet Diet Diet
I II III IV V
normal fat-rich carbohydrate-rich low-fat therapeutic regimen
Fat (%)
Carbohydrate (%)
Protein (%)
40 50 20 5 20
40 20 50 45 60
20 30 30 50 20
Fat: 39% saturated fatty acids, 61% unsaturated fatty acids
Table 3. Serum triglycerides (TG) and cholesterol (C) in mg% during different therapeutic and investigative managements Diet I (normal) TG C Patient 1 Patient2 Patient 3
Diet II (fat-rich) C/TGTG
1750350 0.20 2750255 0.09 2600 188 0.07
C
Diet III (carbohydraterich) C/TGTG
5300350 0.07 7600390 0.05 7200430 0.05
C
Diet IV (low-fat)
C/TGTG
1120270 0.24 1200260 0.22 1450230 0.16
C
Diet V (therapeutic) C/TGTG
C
640 190 0.30 450 160 0.36 860 180 0.21 600 220 0.37 720 205 0.28 875 140 0.16
C/TG = ratio of cholesterol over triglycerides
Table 4. Fractionation of cholesterol in lipoproteins under diet III (fat-rich) Cholesterol in plasma
Patient 1 Patient 2 Patient 3
Total mg%
VLDL mg%
LDL mg%
HDL mg%
Esterified % of total
520 485 220
464 448 186
39 24 22
17 13 12
62 54 51
C/TG
o f c h o l e s t e r o l in the l i p o p r o t e i n s revealed no a b n o r m a l c o m p o s i t i o n (Table 4). T h e l o w - f a t diet caused a significant decrease in p l a s m a triglyceride values; 2 days after i n i t i a t i n g this diet the p l a s m a o f all patients b e c a m e c h y l o m i c r o n - f r e e . A s the t h e r a p e u t i c regimen, diet V was e m p l o y e d . U n d e r clinical c o n t r o l triglyceride values d r o p p e d c o n s i d e r a b l y . O n a n o u t p a t i e n t basis the results were n o t fully satisfying with triglycerides a r o u n d 1200 m g / 1 0 0 ml a n d c h y l o m i c r o n s m a c r o s c o p i c a l l y p r e s e n t in all samples. U l t r a c e n t r i f u g a t i o n ( H a v e l et al,, 1955; G o f m a n a n d Elliot, 1949) o f serum after a n o v e r n i g h t fast was p e r f o r m e d before the investigations were initiated a n d while the p a t i e n t s were o n a n o r m a l diet. A large p e a k at a density of 0.90 to 0.94 i n d i c a t e d c h y l o m i c r o n s ; high d e n s i t y l i p o p r o t e i n s were missing; L D L a n d V L D L
Juvenile Familial HypertrigIyceridemia
65
Table 5. Composition of phospholipids (PLP) in plasma, given in rag% in plasma and fractionated in percent of total PLP
Patient 1 Patient 2 Patient 3
Total PLP rag%
Lysolecithin % of total
Sphingomyelin Lecithin % of total % of total
Phosphatidylethanolamine % of total
661 484 243
15.0 t4.2 15.0
10.8 12.7 10.8
6.5 13.5 7.6
45.8 41.4 48.6
Table 6. Phospholipids and corresponding serum values for triglycerides (TG) and cholesterol (C) under clinical therapy with diet V (given in rag%)
Patient 1 Patient 2 Patient 3 Normal
TG
C
Phospholipids
651 662 646
140 132 145
102 39 59 150--250
Table 7. Post-heparin lipolytic activity (Determination: Prof. Greten, Heidelberg)
Patient 1 Patient 2 Patient 3 Normal
2472 nM FFA/ml/h 3813 nM FFA/ml/h 3754 nM FFA/ml/h 10000 nM FFA/ml/h
were reduced in all three patients. W h e n on a normal diet, the composition of plasma phospholipids (Table 5) revealed a decrease in the lecithin fraction and an increase to a b o u t double the n o r m a l a m o u n t in lysolecithin. During the therapeutic regimen with decreased levels of triglycerides and cholesterol, total phospholipids were considerably lower than in normal individuals (Table 6). Post-heparin lipolytic activity ( P H P L A ) was determined in all three patients after a fasting period of 14 hi.The plasma was drawn f r o m the patients 10 rain after injecting 50 I U / k g heparin i.v. and transferred to the analyzing laboratory on ice. Analysis was performed 8 h after sampling. The overall P H P L A was significantly reduced in all three patients (Table 7). The n o r m a l values apply for children in the age groups of our patients. After fractionation 90% of this already decreased lipase activity was f o u n d to be due to liver lipase and only 10% originated f r o m lipoprotein lipase in the blood. The endogenous creatinine clearance was normal in all three patients. On no occasion did urine analysis reveal proteinuria or other pathologic signs. Serum creatinine, and BUN were normal. r For the determination of PHPLA we are grateful to the Laboratory of Prof. Dr. R. Greten, Heidelberg, Clinical Institute for Research in Heart Infarction
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H.J. Sternowsky et al.
Bone marrow aspiration in all three patients revealed foam cells, from moderate degree in the eldest sibling to about 15% of all cells counted in the youngest. Leukopoetic vs. erythropoetic index was normal; megakaryocytes were present.
b) EndocrinoIogic Studies Thyroid stimulating hormone (TSH) was evaluated indirectly by determination of thyroid 13q uptake and measurement of serum protein-bound iodine. In addition, the serum levels of T S H before and after administration of thyrotropinreleasing hormone (TRH) were determined. In the assessment of A C T H secretion the oral 2-day metyrapone test and an A C T H infusion test were employed. Excretion of 17-OH-corticosteroids was measured in urine (Silber and Porter, 1954). Tetrahydrodesoxycortisol and tetrahydrocortisol were measured separately (Bierich et al., 1961) in response to oral administration of metyrapone. Plasma corticosteroids were determined after i.v. infusion of corticotropin (Bierich, 1959). To evaluate growth hormone secretion, serial growth hormone (GH) measurements were performed during four stimulation tests: insulin-induced hypoglycemia, arginine infusion, oral glucose load (Stahnke et al., 1975), and L-dopa administration (Weldon, 1973). G H was determined by double antibody radioimmunoassay (Quabbe, 1969). A peak serum GH concentration of at least 5 n g / m g is taken as a normal G H response in our laboratory (Stahnke et al., 1975). Serum insulin was measured by a modified radioimmunoassay technique (Meade and Klitgard, 1962), using a kit obtained from Hoechst-Behring AG, Frankfurt, West Germany. Serum immunoreactive insulin (IRI) levels were followed during intravenous arginine, subcutaneous glucagon and intravenous glucose tolerance tests. Evaluation of thyroid hormone, T S H and adrenocorticotropin function revealed no endocrine disease. Maximal growth hormone response to different stimulation tests (Table 8) was normal. Basal levels of serum immunoreactive insulin (IRI) were in the normal range as well. Maximum IRI levels clearly above
Table 8. Maximum growth hormone response in ng/ml after stimulation test
Patient 1 Patient 2 Patient 3
Insulin-induced hypoglycemia
Arginine infusion
Oral glucose L-dopa
13.0 18.3 8.7
17.3 6.7 7.3
12.9 NP 10.9
NP = not performed
9.5 NP NP
Juvenile Familial Hypertriglyceridemia
67
Table 9. Maximum serum immunoreactive insulin (IRI) response (~xU/ml) to stimulation tests (normal basal level at 5 [zU/ml)
Intravenous Arginine glucose infusion Patient 1 Patient 2 Patient 3
23.0 121.0 198.0
Normal 71.75 Range _+33.29 (mean_+ 2 SD)
Subcutaneous glucagon
47 67.0 48.0
74 153.0 173.0
28.1 + 37.56
40.7 _+25.19
normal were observed in patients 2 and 3 during two or all three tolerance tests and they were in the upper normal range for the remaining tests. In patient I peak serum IRI response was in the upper normal range in one stimulation test and above normal in another tolerance test (Table 9). Diabetes mellitus was excluded by intravenous glucose loading test with 0 . 5 g / k g D-glucose, infused within 2mins. The decrease of blood glucose, determined at 10-rain intervals after infusion for 40 mins gave no indication of diabetes mellitus. On the contrary, in patients 2 and 3, serum glucose decreased rapidly to values of 83 and 76 mg/100 ml, respectively, after 30 rains, although initial values of 240 and 260 mg/100 ml had been reached after 10 mins.
Discussion
Familial hyperlipoproteinemia is defined by the following major criteria: type I lipoprotein pattern in lipoprotein electrophoresis and deficiency in post-heparin lipolytic activity. Minor criteria might help to establish the diagnosis: type I pattern in a close relative, abdominal pain, eruptive xanthoma, pancreatitis, and fat-induced chylomicronemia (Frederickson and Levy, 1972). The following diseases should be excluded to avoid an almost identical phenocopy, a secondary hyperlipoproteinemia: juvenile diabetes mellitus, chronic renal failure, 1,6-GPD deficiency, and hyperuricemia. The patients reported here meet all major criteria. As far as the minor points are concerned, there is no abnormal lipoprotein pattern in the mother, the increased pre-fl-lipoproteins in the father are considered secondary to alimentary obesity. On the other hand, there are three affected children out of eight, indicating horizontal manifestation. Vertical manifestation has not been found in familial hypertriglyceridemia (Frederickson and Levy, 1972). Abdominal pain was present in patient 2, it is not clear, however, whether these pains can be attributed to pancreatitis in hyperlipoproteinemia type I rather than to upper gastrointestinal infection. In our patients hyperchylomicronemia could be induced by fat intake (Table 3), whereas the carbohydrate-rich diet did not increase serum triglyceride. The
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H.J. Sternowsky et al.
somewhat increased serum cholesterol values during the carbohydrate-rich diet are considered hangover values from the fat-rich diet immediately preceding. Post-heparin lipolytic activity, which measures the lipoprotein lipase momentarily displaced in the plasma after injection of heparin, is well below the normal activity, which has been found in age- and sex-matched children in the analyzing laboratory. Although only the protamine inhibitable activity is low in familial type I hyperlipoproteinemia and the protamine-resistant compartment seems to be normal (Jones, 1973) the very low overall activity found seems to indicate a defect in the .protamine inhibitable part as well. From these data, together with the lipoprotein electrophoresis in both media, and from the ultracentrifugation, we consider the diagnosis of familial hyperlipoproteinemia type I valid. Moreover, the formation of foam cells in bone marrow which develops as a result of phagocytosis of large numbers of chylomicrons by histiocytes (Ferrans et al., 1973), indicates that for a long time a consistent increase in plasma chylomicrons has prevailed, a condition usually found only in familial hyperlipoproteinemia type I. Our patients were found to be of small stature, two of them well below the third percentile. Values for height and weight were extracted from European, in fact British children (Tanner et al., 1966), whereas the patients reported here were born and raised for some years in the Near East. It is well known that growth largely depends on race (Prader, 1971). Despite these facts and considering that there were no weight or height standards from Turkish children available to us, we stress the point that the father and the remaining five siblings were of normal growth, comparable to Middle European standards. The retardation in bone maturation is only observed in the three children affected and thus may serve as further proof that the small stature is not of racial origin. The family history provides information concerning diminished genetic height potential in the mother's family, so this might play a role in the etiology of growth retardation. However, comparison with the parent-specific standards for height (Garn and Rohmann, 1968) reveals growth differences of --10.3 cm in patient 2 to - - 1 4 . 2 c m in patient 3 and thus renders this assumption improbable. Since endocrine studies were within normal limits in all three patients, their diminished growth apparently is not due to hormonal factors. We suspect a connection between growth and bone age retardation and the underlying metabolic diseases. It is not clear that our patients are the only ones with short stature and familial hypertriglyceridemia, since height, weight and endocrine situations were not reported in previous cases (Ditschuneit et al., 1972; Dt~chting, 1974; Ferrans et al., 1973; Frederickson and Breslow, 1973). The pathogenesis of this connection hitherto remains obscure. It is known, however, that in glycolipid storage diseases small stature is pathognomonic. It is not clear yet, if a storage phenomenon of triglyceride bears any pathogenetic significance. Peak serum immunoreactive insulin (IRI) response to one to three stimulation tests was clearly above normal in all three patients. It is well known that insulin levels are increased in clinical states of insulin resistance as in obesity, glucocorticoid therapy, Cushing's syndrome, estrogen therapy, uremia, acromegaly, and pregnancy (Williams and Porte, 1974); evidence for these conditions in our patients was absent. Similar reasoning applies to beta-cell adenoma and beta-cell
Juvenile Familial Hypertriglyceridemia
69
hyperplasia associated with increased insulin secretion. So the reason for hyperinsulinism in our patients at the m o m e n t cannot be elucidated. As has been reported earlier (Ditschuneit et al., 1972) it is not difficult to achieve a decrease of triglyceride values during hospitalization. However, it is not practical to a t t e m p t triglyceride values of less than 800 rag/100 ml on an outpatient basis: unrealistic dietary prescriptions will not be followed and thus inhibit control over the metabolic status. Moreover, there are no reports of statistically significant increases in pancreatitis, a b d o m i n a l colic, or ischemic heart disease when these patients with familial hypertriglyceridemia are monitored on a level of about 800--1000 mg/ 100 ml triglycerides. A further attempt to localize the metabolic defect in our patients with familial hypertriglyceridemia type I in c o m b i n a t i o n with growth retardation and increased glucose assimilation in the adenylcyclase-cyclic A M P - p r o t e i n k i n a s e triglyceridlipase system (Kaukel et al., 1975) has raised the possibility of a defect in this lipolytic cascade. Complete investigations of this point will be reported elsewhere.
References
Berger, H., Richter, A., Gilardi, A., Wagner, H.: Essential, familial hyperlipemia in a two year old child. Annales Paediatrici 199, 445 (1962) Bierich, J. R.: Methoden zur Bestimmung der freien Corticosteroide im Plasma. Endokrinologie 37, 25 (1959) Bierich, J. R., Sch6nberg, D., Eckler, E.: Die Prtifung der corticotropen Funktion der Hypophyse mit Metopiron. In: 8. Symposium der Deutschen Gesellschaft ftir Endokrinologie, l.--3. 3. 1961, p. 351. Berlin-G6ttingen-Heidelberg: Springer 1962 Braunsteiner, H., Berger, H., Sailer, S., Sandhofer, F.: Untersuchungen bei einem Fall yon fettinduzierter (exogener) Hypertriglyceridfimie. Schweizerische Medizinische Wochenschrift 98, 458 (1968) Ditschuneit, H., Brmer, H. J., Eckart, M., Faulhaber, J. D., Hiller, G., U16r, U., Rakow, A., Thun, H. J.: Familienuntersuchungen bei Hyperlipoprotein~imie Typ I. Verhandlungen der Deutschen Gesellschaft ftir Innere Medizin 76, 1339 (1972) D~ichting, M.: Essentielle Hyperlipoprotein~imie (Typ I, B~rger-Grtitz) bei einem 4 Wochen alten S~iugling. Zeitschrift ftir Kinderheilkunde 116, 213 (1974) Ferrans, V.J., Roberts, W. C., Levy, R. I., Frederickson, D. S.: Chylomicrons and the formation of foam cells in type I hyperlipoproteinaemia. American Journal of Pathology 70, 253 (1973) Frederickson, D. S., Levy, R. I., Lees, R. S.: Fat transport in lipoproteins--an integrated approach to mechanisms and disorders. New England Journal of Medicine 276, 34, 94, 148, 215, 273 (1967) Frederickson, D. S., Levy, R. I.: Familial hyperlipoproteinaemia. In: The Metabolic Basis of Inherited Disease. Stanbury, J. D., Wyngaarden, J. D., Frederickson, D. S., Eds., 3rd Edition, p. 555. New York: McGraw-Hill 1972 Frederickson, D. S., Breslow, J. L.: Primary hyperlipoproteinaemia in infants. Medical Annals of North America 23, 315 (1973) Garn, S. M., Rohmann, C. G.: Interaction of nutrition and genetics in the timing of growth and development. Pediatric Clinics of North America 13, 353 (1968) Glueck, C. J., Kaplan, A. P., Levy, R. I., Greten, H., Gralnick, H., Frederickson, D. S.: A new mechanism of endogenous hypertriglyceridemia. Annals of Internal Medicine 71, 1051 (1969)
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Glueck, C. J., Fallat, R. W., Tsamg, R.: Hypercholesterolemia and hypertriglyceridemia in children. American Journal of Diseases of Children. 128, 569 (1974) Goldstein, J. L., Hazzard, W. R., Schrott, H. G., Bierman, E. L., Motulsky, A. G.: Hyperlipidemia in coronary heart disease, I. Journal of Clinical Investigation 52, 1533 (1973) Gofman, J. W., Elliot, H. A.: Ultracentrifugal studies of lipoproteins in human serum. Journal of Biological Chemistry 179, 973 (1949) Grabner, W.: Mikrolipidelektrophorese auf Celluloseacetatfolie. Clinica Chimiea Acta 28, 299 (1970) Greulich, W. W., Pyle, S. I.: Radiographic atlas of skeletal development of the hand and wrist. London: Oxford University Press 1959 Havel, R. J., Eder, H. A., Bragnsen, J. H.: The distribution and chemical composition of ultracentrifugally separated lipoproteins in human serum. Journal of Clinical Investigation 34, 1345 (1955) Havel, R. J., Gordon, R. S.: Idiopathic hyperlipemia: Metabolic studies in an affected family. Journal of Clinical Investigation 40, 1777 (1961) Hobbelen, P. M. J., Coert, A., Geelen, A. A., van der Vries, J.: Interaction of steroids with serum lipoproteins. Biochemical Pharmacology 24, 165 (1975) Jones, R. J.: The hyperlipoproteinemias, detection, diagnosis, and management. Medical Clinics of North America 57, 47 (1973) Kaukel, E., Sternowsky, H. J., Gaertner, U.: Juvenile familial hypertriglyceridemia: Defect in adenylcyclase-proteinkinase-triglyceridlipase system (?). Pediatric Research 9, 866 (1975) Krauss, R., Levy, R. I., Windmueller, H. G., Miller, L., Frederickson, D. S.: Selective measurement of lipoprotein lipase and hepatic triglyceride lipase in post-heparin plasma. Journal of Clinical Investigation 51, 52 a (1972) McKusiek, V. A.: Heritable disorders of connective tissue. 3rd Ed., p. 50. St. Louis: C. V. Mosby (1966) Meade, R. C., Klitgard, H. M.: A simplified method for immunoassay of human serum insulin. Journal of Nuclear Medicine 3, 407 (1962) Mellies, M., Glueck, C. J., Fallat, R. W., Tsang, R.:Familial and aquired hyperlipoproteinemias in children and adolescents. Postgraduate Medicine 56, 94 (1974) Prader, A.: Wachstum und Entwicklung. In: Klinik der Inneren Sekretion. A. Labhardt, Ed., p. 1047. Berlin-Heidelberg-New York: Springer 1971 Quabbe, H. J.: Radioimmunologische Bestimmung yon Wachstumshormon im Plasma des Menschen. Zeitsehrift fiir Klinische Chemic und Klinische Biochemie 7, 259 (1969) Silber, R.H., Porter, C. C.: The determination of 17,21-dihydroxy-20-ketosteroids in urine and plasma. Journal of Biological Chemistry 210, 923 (1954) Stahnke, N., Wiebel, J., Willig, P., Blunck, W.: Screeningtests zum Ausschlul~eines Wachstumshormonmangels. Monatsschrift ft~r Kinderheilkunde 123, 335 (1975) Stroink, J. B. A.: Composition and consumption of dietary fats in USA, UK, and Common Market countries in 1961. Nutrition and Diet 9, 56 (1967) Tanner, J. M.: Growth and endocrinology of the adolescent. In: Endocrine and genetic diseases of childhood. L. I. Gardner, Ed., p. 19. Philadelphia: W. B. Saunders 1969 Tanner, J. M., Whitehouse, R, H., Takaishi, M.: Standards from birth to maturity for height, weight, height velocity, and weight velocity: British children 1965. Archives of Diseases in Childhood 41, 454, 613 (1966) Vince, F. P., Tanner, J. M.: Treatment of dwarfism with HGH. In: Human Growth Hormone. A. S. Mason, Ed., p. 158. London: W. Heinemann Med. Books Ltd. 1972 Weldon, V. V.: The use of L-DOPA in the diagnosis of hyposomatism in children. Journal of Clinical Endocrinology 32, 42 (1973) Williams, R. H., Porte, D.: The Pancreas. In: Textbook of Endocrinology. Ed. R. H. Williams. Philadelphia: W. B. Saunders 1974
Received September 15, 1976
Europ. J. Pediat. 125, 59--70 (1977)
Pediatrics 9 by Springer-Verlag 1977
Juvenile Familial Hypertriglyceridemia and Growth Retardation Clinical and Biochemical Observations in Three Siblings
Hans J. Sternowsky I, U. Gaertner*, N. Stahnke 1, and E. Kaukel 2 ~Department of Paediatrics, Martinistrage 52, D-2000 Hamburg 20, Federal Republic of Germany, and 2Department of Internal Medicine, University Hospital Hamburg-Eppendorf, University of Hamburg, Martinistral~e 52, D-2000 Hamburg 20, Federal Republic of Germany
Abstract. Familial hypertriglyceridemia or hyperlipoproteinemia type I was detected in three siblings aged 6, 11, and 14 of an otherwise normal Turkish family of 10 members. Initial values ranged from 1780 to 3750 mg/100 ml triglycerides in the milky white serum; cholesterol was normal. Lipoprotein pattern on agarose and acrylamide gel revealed a heavy band of chylomicrons and missing HDL; post-heparin lipolytic activity was decreased to about 30% of normal. Chylomicronemia could be induced by a fat-rich (50% of total calories) diet, but not by carbohydrates. On a low fat diet (5%) during hospitalization chylomicrons disappeared, and triglycerides decreased to about 450mg/100ml. Phenocopies of hypertriglyceridemia could be excluded. All three patients were the only members of the family who were small, below the third percentile. Their bone age was retarded from 18 to 30 months. There was no indication for an endocrine cause of the growth retardation: four different stimulation tests revealed normal growth hormone response, thyroid and adrenal functions were not impaired; sexual development was normal. Increased glucose assimilation was observed during intravenous and oral glucose load. Peak serum insulin response was above normal during stimulation tests. The possible etiologic role of hypertriglyceridemia in this concomitant growth retardation is discussed. Key words: Hypertriclyceridemia - Hyperlipoproteinemia - Growth retardation.
Zusammenfassung. Bei drei Kindern, 6, 11 und 14 Jahre, einer sonst nicht auff~illigen ttirkisehen zehnk6pfigen Familie wurde eine Hyperlipoprotein~imie Typ I nach Frederickson gefunden. Initial betrugen die Triglyceridwerte des milchig-weiBen Serums 1780 bis 3750 mg/dl, Serum-Cholesterin war nicht erhOht. In der Lipoproteinelektrophorese auf Agarose- und Acrylamidgel * P r e s e n t A d d r e s s : University of Konstanz, Department of Biology, D-7750 Konstanz, Federal Republic of Germany
60
H.J. Sternowsky et al. stellten sich eine ausgeprggte Bande der Chylomikronen, jedoch keine der H D L dar, die post-heparin lipolytische Aktivit~it war auf 30% der Norm erniedrigt. Bei fettreicher (50% der Gesamtkalorien) Kost konnten Chylomikronen induziert werden, Kohlenhydrate hatten diesen Effekt nicht. Bei fettarmer (5%) Kost verschwanden die Chylomikronen w~thrend der station~tren Behandlung, die Triglyceridwerte fielen auf etwa 450 mg/dl. Anhalt ftir Ph~tnokopien wurde nicht gefunden. Als einzige Familienmitglieder waren alte drei Patienten zu klein, die Kt~rpergrrBe lag bei allen unter der dritten Perzentile. Wiederum hatten nur die Patienten ein retardiertes Knochenalter, minus 18 bis 30 Monate. Es fand sich jedoch kein Hinweis ftir eine endokrinologische Ursache der Wachstumsverz6gerung: Bei 4 verschiedenen Stimulationstests normaler Anstieg des Serum-STH, Schilddrtisen- und Nebennierenrindenfunktionen waren unbeeintr~ichtigt, die Sexualentwicklung war altersentsprechend. W~thrend der intraven/Ssen und der oralen Glukosebelastung wurde eine erhrhte Glukoseassimilation gefunden. Jedoch waren die Serum-Insulinwerte w~ihrend dieser Stimulationstest im Normbereich. Die M6glichkeit, dab die angeborene Hypertriglycerid~imie eine kausale Rolle bei der Entstehung der Wachstumsverz6gerung spielt, mug diskutiert werden.
Introduction
Familial hypertriglyceridemia is a rare disorder of fat metabolism. It was named familial type I hyperlipoproteinemia by Frederickson et al. (1967). It is defined by a genetically determined increase in the plasma concentration of chylomicrons. A slight decrease in low-density lipoproteins (LDL) and high-density lipoproteins (HDL) may occur. Plasma cholesterol levels are normal or moderately increased, the cholesterol versus triglyceride quotient is smaller than 0.2 (Frederickson and Breslow, 1973; Jones, 1973; Glueck et al., 1964). These values are found in patients on unrestricted diet. About 18% of the more than 60 cases reported up to date (May, 1976) were detected in childhood and infancy (Ditschuneit et al., 1972; Havel and Gordon, 1961; Braunsteiner et al., 1968; Dtichting, 1974; Ferrans et al., 1973; Frederickson and Breslow, 1973; Berger et al., 1962), usually because of eruptive xanthoma, abdominal pain, enlarged liver and spleen, and lipemia retinalis. One of the most obvious findings is that the plasma, after standing for 12 h at 4~ develops a chylomicron-composed, creamlike upper layer, whereas the infranate becomes clear. A diet low in fat (less than 15% of total calories) and high in proteins and carbohydrates causes the chylomicrons to disappear or decrease considerably, corresponding to a decrease of the triglyceride and cholesterol levels. Its pathogenetic mechanisms are not well known. Supposedly there is a defect in the potential to remove chylomicrons from the blood: the lipolytic activity is decreased. The enzyme responsible for this extracellular lipolysis is lipoprotein lipase, one of several triglyceride lipases found in human blood (Frederickson et al., 1967; Frederickson and Levy,1972). It hydrolyzes the ester bonds of chylomicrons and is activated by heparin, but not by epinephrine (Glueck et al., 1969).
Juvenile Familial Hypertriglyceridemia
61
Protamine, sodium pyrophosphate, and high concentrations of sodium chloride a r e p o t e n t i n h i b i t o r s o f this e n z y m e . T h e r e is n o r e p o r t o n h y p e r t r i g l y c e r i d e m i a d u r i n g c h i l d h o o d w h e r e r e t a r d e d g r o w t h was a n essential p a r t o f t h e clinical observations. In this respect a n d in v i e w o f the r a r i t y o f the disease, t o g e t h e r w i t h t h e f a c t t h a t its p a t h o g e n e s i s r e m a i n s o b s c u r e , we r e p o r t t h r e e cases o f a f a m i l y w i t h e i g h t c h i l d r e n , w h o c a m e to o u r a t t e n t i o n w h e n t h e y w e r e a d m i t t e d f o r s e v e r e scabies infestation.
Case Reports The three patients are from a Turkish family. They reported to the hospital with severe secondary infections of almost the whole body following scabies infestation. There were eight children, six of whom suffered from scabies; the parents and the two eldest siblings were not affected. On routine blood determinations lipemic sera were found and further metabolic investigations were initiated. Patient 1. O. G. was the youngest child, aged 5 years and 3 months when he was first admitted. He was the eighth child of the unrelated and apparently healthy parents. Pregnancy and birth as well as postnatal development were normal. He had never previously been hospitalized until admission for severe superinfeeted scabies with high temperature, general edema, and enlarged axillary and inguinal lymph nodes. The liver was 6 cm below the costal margin, the spleen 5 cm. The abdomen was distended, but the child did not complain of abdominal pain. Triglycerides were 2600mg/lOOml and total cholesterol was repeatedly normal. Lipemia retinalis was diagnosed during ophthalmologic examination. Patient 2. G. G. was 11 years old on admission for superinfected scabies. She had never been under medical care before. Pregnancy, birth, and postnatal development were normal. She had signs of acute inflammation similar to her brother, patient i. The liver was enlarged by 3 cm; the spleen was not palpable. She complained of upper intestinal pain and had mild diarrhea. Alphas-amylases were normal in urine and serum. After 2 days of treatment for gastrointestinal infection there were no more complaints. Serum triglycerides were increased to 3750 mg/100 ml; cholesterol was repeatedly normal. She too had lipemia retinalis. Patient 3. After the admission of these two patients the whole family was examined for triglyceride and cholesterol levels as well as height and bone age. One more affected child was found: He was an apparently healthy boy of 14 years and 9 months. There were no signs of inflammation, and the liver and spleen were not enlarged. Triglycerides were increased to 1780 mg/100 ml; cholesterol was normal. Again lipemia retinalis was found.
Additional measurements of endocrinologic status were performed in all three patients. The height and weight measurements are referred to standard charts indicating the percentile for chronological age (Tanner et al., 1966); height measurements are also presented as standard deviation scores (SDS) (Vince and Tanner, 1972). As an index of skeletal proportions the ratio of upper segment (US) to lower segment (LS) was determined and compared to normal standards (McKusick, 1966). Skeletal maturity was estimated from roentgenograms of the left hand and wrist by comparison with a standard atlas (Greulich and Pyle, 1959). The development of puberty was assessed by comparison with genital development changes during puberty (Tanner, 1969). The size of the testes was assessed by palpation in comparison with models of testicular shape (Prader orchidometer) of known volume (Prader, 1971). Patient 1. Bone maturation showed 2 years retardation; height was I5.5 cm below the third percentile; SDS --2.83, US : LS 1.143 (more than two SD above mean for age); weight was
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H . J . Sternowsky et al.
Fig. 1. Three siblings with familial hypertriglyceridemia and short stature: aged 5, 11, and 15 years
slightly above the third percentile for chronological age and between the 25th and 50th percentile for height age. Head circumference 50 cm, testis volume 1 ml. Patient 2. Bone age retarded 1.5 years; height - - 11.5 cm, between tenth and third percentile; SDS - - 1.595; US : LS 1.029 (more than two SD above mean for age); weight between 10th and 25th percentile for chronological age and between 50th and 75th percentile for height age. Head circumference 50.5 cm, breast development B 4, pubic hair P 2, axillary hair beginning. Patient 3. Bone age retarded 2 years; height --17.3 cm, below the third percentile; SDS --2.595; US : LS 1.010 (more than two SD above mean for age); weight between the 10th and 25th percentile for chronological age and slightly above the 75th percentile for height age. Head circumference 54 cm, pubic hair P 5, testis volume 20 ml, axillary hair +++.
The pedigree reveals three affected children with triglyceride levels exceeding the 99th percentile (Glueck et al., 1974), adjusted for age. All other members of this family of 10 had normal triglyceride levels. Including the patients just described every member of the family had normal cholesterol values when adjusted for age (Goldstein et al., 1973).
Juvenile Familial Hypertriglyceridemia
63
We were not able to study the grandparents of our patients. They are reported to have succumbed to endemic infection, seemingly unrelated to hyperlipemic symptoms. Thus we have to assume horizontal manifestation of hypertriglyceridemia in 37,5% of the offspring. The lipoprotein pattern on lipoprotein eleetrophoresis on acetate foil was normal in the mother and five siblings. The father had an increase in pre-fl-lipoproteins to 55.1%. There were no clinical signs of diabetes, hypothyroidism, nephrotic disease or hyperuricemia. He was 35 years of age and 23% overweight for height. The height of the father and the unaffected children was normal, between the 50th and 75th percentile. The mother, however, was 149 cm tall, thus below the third percentile. She reported that her parents, too, were of small stature, and that her first menstrual bleeding was at age 13. Bone age in all unaffected members of the family was not retarded and did not show deviations of more than 3 months from the chronological age.
Results of Special Studies
a) Lipoproteins Massive c h y l o m i c r o n e m i a was demonstrated by leaving the lactescent plasma, taken after a fasting period of 14 hours, overnight at 4~ Chylomicrons rose to the top to f o r m a creamy layer; the infranate remained clear. Lipoprotein electrophoresis on cellulose acetate foil (Grabner, 1970) was performed in all three patients once a week during the course of the clinical evaluation. Initially the pattern for chylomicron-rich plasma and the clear infranate were determined (Table 1). In the lactescent plasma, alpha-lipoproteins could never be d e m o n strated, chylomicrons were not present in the infranate, and fl-lipoproteins were decreased in all three patients. The additional lipoprotein electrophoresis on polyacrylamid gel gave confirming results. Initially the patients were kept on a regular diet of their choice. The diet was analyzed once and then kept constant as far as calories, percentage of fat, quality of fat, percentage of carbohydrates and percentage of protein were concerned (Table 2, diet I). The ratio of saturated over unsaturated and highly unsaturated fatty acids reflects the n o r m a l composition of fat intake in this country (Stroink, 1967) with 39% saturated and 61% unsaturated fat. Following the initial phase of two weeks, three feeding studies were performed, each lasting 7 days. The diets were fat-rich (II), carbohydrate-rich (Ill) and low in fat (IV). The f o r m a t i o n of chylomicrons and triglycerides was f o u n d to be influenced by the fat-rich diet (Table 3), but not by the carbohydrate-rich diet. D u r i n g the fat-rich regimen cholesterol values were increased moderately. The fractionation
Table 1. Lipoprotein electrophoresis (values given in %) of the initially found serum without dietary measures Lactescent serum
Patient 1 Patient 2 Patient 3
Chylo
pre-beta beta
alpha
64.0 74.2 76.5
28.1 11.4 13.1
0 0 0
7.9 14.4 10.4
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H.J. Sternowsky et al.
Table 2. Composition of diets during clinical investigation (in % of total calories)
Diet Diet Diet Diet Diet
I II III IV V
normal fat-rich carbohydrate-rich low-fat therapeutic regimen
Fat (%)
Carbohydrate (%)
Protein (%)
40 50 20 5 20
40 20 50 45 60
20 30 30 50 20
Fat: 39% saturated fatty acids, 61% unsaturated fatty acids
Table 3. Serum triglycerides (TG) and cholesterol (C) in mg% during different therapeutic and investigative managements Diet I (normal) TG C Patient 1 Patient2 Patient 3
Diet II (fat-rich) C/TGTG
1750350 0.20 2750255 0.09 2600 188 0.07
C
Diet III (carbohydraterich) C/TGTG
5300350 0.07 7600390 0.05 7200430 0.05
C
Diet IV (low-fat)
C/TGTG
1120270 0.24 1200260 0.22 1450230 0.16
C
Diet V (therapeutic) C/TGTG
C
640 190 0.30 450 160 0.36 860 180 0.21 600 220 0.37 720 205 0.28 875 140 0.16
C/TG = ratio of cholesterol over triglycerides
Table 4. Fractionation of cholesterol in lipoproteins under diet III (fat-rich) Cholesterol in plasma
Patient 1 Patient 2 Patient 3
Total mg%
VLDL mg%
LDL mg%
HDL mg%
Esterified % of total
520 485 220
464 448 186
39 24 22
17 13 12
62 54 51
C/TG
o f c h o l e s t e r o l in the l i p o p r o t e i n s revealed no a b n o r m a l c o m p o s i t i o n (Table 4). T h e l o w - f a t diet caused a significant decrease in p l a s m a triglyceride values; 2 days after i n i t i a t i n g this diet the p l a s m a o f all patients b e c a m e c h y l o m i c r o n - f r e e . A s the t h e r a p e u t i c regimen, diet V was e m p l o y e d . U n d e r clinical c o n t r o l triglyceride values d r o p p e d c o n s i d e r a b l y . O n a n o u t p a t i e n t basis the results were n o t fully satisfying with triglycerides a r o u n d 1200 m g / 1 0 0 ml a n d c h y l o m i c r o n s m a c r o s c o p i c a l l y p r e s e n t in all samples. U l t r a c e n t r i f u g a t i o n ( H a v e l et al,, 1955; G o f m a n a n d Elliot, 1949) o f serum after a n o v e r n i g h t fast was p e r f o r m e d before the investigations were initiated a n d while the p a t i e n t s were o n a n o r m a l diet. A large p e a k at a density of 0.90 to 0.94 i n d i c a t e d c h y l o m i c r o n s ; high d e n s i t y l i p o p r o t e i n s were missing; L D L a n d V L D L
Juvenile Familial HypertrigIyceridemia
65
Table 5. Composition of phospholipids (PLP) in plasma, given in rag% in plasma and fractionated in percent of total PLP
Patient 1 Patient 2 Patient 3
Total PLP rag%
Lysolecithin % of total
Sphingomyelin Lecithin % of total % of total
Phosphatidylethanolamine % of total
661 484 243
15.0 t4.2 15.0
10.8 12.7 10.8
6.5 13.5 7.6
45.8 41.4 48.6
Table 6. Phospholipids and corresponding serum values for triglycerides (TG) and cholesterol (C) under clinical therapy with diet V (given in rag%)
Patient 1 Patient 2 Patient 3 Normal
TG
C
Phospholipids
651 662 646
140 132 145
102 39 59 150--250
Table 7. Post-heparin lipolytic activity (Determination: Prof. Greten, Heidelberg)
Patient 1 Patient 2 Patient 3 Normal
2472 nM FFA/ml/h 3813 nM FFA/ml/h 3754 nM FFA/ml/h 10000 nM FFA/ml/h
were reduced in all three patients. W h e n on a normal diet, the composition of plasma phospholipids (Table 5) revealed a decrease in the lecithin fraction and an increase to a b o u t double the n o r m a l a m o u n t in lysolecithin. During the therapeutic regimen with decreased levels of triglycerides and cholesterol, total phospholipids were considerably lower than in normal individuals (Table 6). Post-heparin lipolytic activity ( P H P L A ) was determined in all three patients after a fasting period of 14 hi.The plasma was drawn f r o m the patients 10 rain after injecting 50 I U / k g heparin i.v. and transferred to the analyzing laboratory on ice. Analysis was performed 8 h after sampling. The overall P H P L A was significantly reduced in all three patients (Table 7). The n o r m a l values apply for children in the age groups of our patients. After fractionation 90% of this already decreased lipase activity was f o u n d to be due to liver lipase and only 10% originated f r o m lipoprotein lipase in the blood. The endogenous creatinine clearance was normal in all three patients. On no occasion did urine analysis reveal proteinuria or other pathologic signs. Serum creatinine, and BUN were normal. r For the determination of PHPLA we are grateful to the Laboratory of Prof. Dr. R. Greten, Heidelberg, Clinical Institute for Research in Heart Infarction
66
H.J. Sternowsky et al.
Bone marrow aspiration in all three patients revealed foam cells, from moderate degree in the eldest sibling to about 15% of all cells counted in the youngest. Leukopoetic vs. erythropoetic index was normal; megakaryocytes were present.
b) EndocrinoIogic Studies Thyroid stimulating hormone (TSH) was evaluated indirectly by determination of thyroid 13q uptake and measurement of serum protein-bound iodine. In addition, the serum levels of T S H before and after administration of thyrotropinreleasing hormone (TRH) were determined. In the assessment of A C T H secretion the oral 2-day metyrapone test and an A C T H infusion test were employed. Excretion of 17-OH-corticosteroids was measured in urine (Silber and Porter, 1954). Tetrahydrodesoxycortisol and tetrahydrocortisol were measured separately (Bierich et al., 1961) in response to oral administration of metyrapone. Plasma corticosteroids were determined after i.v. infusion of corticotropin (Bierich, 1959). To evaluate growth hormone secretion, serial growth hormone (GH) measurements were performed during four stimulation tests: insulin-induced hypoglycemia, arginine infusion, oral glucose load (Stahnke et al., 1975), and L-dopa administration (Weldon, 1973). G H was determined by double antibody radioimmunoassay (Quabbe, 1969). A peak serum GH concentration of at least 5 n g / m g is taken as a normal G H response in our laboratory (Stahnke et al., 1975). Serum insulin was measured by a modified radioimmunoassay technique (Meade and Klitgard, 1962), using a kit obtained from Hoechst-Behring AG, Frankfurt, West Germany. Serum immunoreactive insulin (IRI) levels were followed during intravenous arginine, subcutaneous glucagon and intravenous glucose tolerance tests. Evaluation of thyroid hormone, T S H and adrenocorticotropin function revealed no endocrine disease. Maximal growth hormone response to different stimulation tests (Table 8) was normal. Basal levels of serum immunoreactive insulin (IRI) were in the normal range as well. Maximum IRI levels clearly above
Table 8. Maximum growth hormone response in ng/ml after stimulation test
Patient 1 Patient 2 Patient 3
Insulin-induced hypoglycemia
Arginine infusion
Oral glucose L-dopa
13.0 18.3 8.7
17.3 6.7 7.3
12.9 NP 10.9
NP = not performed
9.5 NP NP
Juvenile Familial Hypertriglyceridemia
67
Table 9. Maximum serum immunoreactive insulin (IRI) response (~xU/ml) to stimulation tests (normal basal level at 5 [zU/ml)
Intravenous Arginine glucose infusion Patient 1 Patient 2 Patient 3
23.0 121.0 198.0
Normal 71.75 Range _+33.29 (mean_+ 2 SD)
Subcutaneous glucagon
47 67.0 48.0
74 153.0 173.0
28.1 + 37.56
40.7 _+25.19
normal were observed in patients 2 and 3 during two or all three tolerance tests and they were in the upper normal range for the remaining tests. In patient I peak serum IRI response was in the upper normal range in one stimulation test and above normal in another tolerance test (Table 9). Diabetes mellitus was excluded by intravenous glucose loading test with 0 . 5 g / k g D-glucose, infused within 2mins. The decrease of blood glucose, determined at 10-rain intervals after infusion for 40 mins gave no indication of diabetes mellitus. On the contrary, in patients 2 and 3, serum glucose decreased rapidly to values of 83 and 76 mg/100 ml, respectively, after 30 rains, although initial values of 240 and 260 mg/100 ml had been reached after 10 mins.
Discussion
Familial hyperlipoproteinemia is defined by the following major criteria: type I lipoprotein pattern in lipoprotein electrophoresis and deficiency in post-heparin lipolytic activity. Minor criteria might help to establish the diagnosis: type I pattern in a close relative, abdominal pain, eruptive xanthoma, pancreatitis, and fat-induced chylomicronemia (Frederickson and Levy, 1972). The following diseases should be excluded to avoid an almost identical phenocopy, a secondary hyperlipoproteinemia: juvenile diabetes mellitus, chronic renal failure, 1,6-GPD deficiency, and hyperuricemia. The patients reported here meet all major criteria. As far as the minor points are concerned, there is no abnormal lipoprotein pattern in the mother, the increased pre-fl-lipoproteins in the father are considered secondary to alimentary obesity. On the other hand, there are three affected children out of eight, indicating horizontal manifestation. Vertical manifestation has not been found in familial hypertriglyceridemia (Frederickson and Levy, 1972). Abdominal pain was present in patient 2, it is not clear, however, whether these pains can be attributed to pancreatitis in hyperlipoproteinemia type I rather than to upper gastrointestinal infection. In our patients hyperchylomicronemia could be induced by fat intake (Table 3), whereas the carbohydrate-rich diet did not increase serum triglyceride. The
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H.J. Sternowsky et al.
somewhat increased serum cholesterol values during the carbohydrate-rich diet are considered hangover values from the fat-rich diet immediately preceding. Post-heparin lipolytic activity, which measures the lipoprotein lipase momentarily displaced in the plasma after injection of heparin, is well below the normal activity, which has been found in age- and sex-matched children in the analyzing laboratory. Although only the protamine inhibitable activity is low in familial type I hyperlipoproteinemia and the protamine-resistant compartment seems to be normal (Jones, 1973) the very low overall activity found seems to indicate a defect in the .protamine inhibitable part as well. From these data, together with the lipoprotein electrophoresis in both media, and from the ultracentrifugation, we consider the diagnosis of familial hyperlipoproteinemia type I valid. Moreover, the formation of foam cells in bone marrow which develops as a result of phagocytosis of large numbers of chylomicrons by histiocytes (Ferrans et al., 1973), indicates that for a long time a consistent increase in plasma chylomicrons has prevailed, a condition usually found only in familial hyperlipoproteinemia type I. Our patients were found to be of small stature, two of them well below the third percentile. Values for height and weight were extracted from European, in fact British children (Tanner et al., 1966), whereas the patients reported here were born and raised for some years in the Near East. It is well known that growth largely depends on race (Prader, 1971). Despite these facts and considering that there were no weight or height standards from Turkish children available to us, we stress the point that the father and the remaining five siblings were of normal growth, comparable to Middle European standards. The retardation in bone maturation is only observed in the three children affected and thus may serve as further proof that the small stature is not of racial origin. The family history provides information concerning diminished genetic height potential in the mother's family, so this might play a role in the etiology of growth retardation. However, comparison with the parent-specific standards for height (Garn and Rohmann, 1968) reveals growth differences of --10.3 cm in patient 2 to - - 1 4 . 2 c m in patient 3 and thus renders this assumption improbable. Since endocrine studies were within normal limits in all three patients, their diminished growth apparently is not due to hormonal factors. We suspect a connection between growth and bone age retardation and the underlying metabolic diseases. It is not clear that our patients are the only ones with short stature and familial hypertriglyceridemia, since height, weight and endocrine situations were not reported in previous cases (Ditschuneit et al., 1972; Dt~chting, 1974; Ferrans et al., 1973; Frederickson and Breslow, 1973). The pathogenesis of this connection hitherto remains obscure. It is known, however, that in glycolipid storage diseases small stature is pathognomonic. It is not clear yet, if a storage phenomenon of triglyceride bears any pathogenetic significance. Peak serum immunoreactive insulin (IRI) response to one to three stimulation tests was clearly above normal in all three patients. It is well known that insulin levels are increased in clinical states of insulin resistance as in obesity, glucocorticoid therapy, Cushing's syndrome, estrogen therapy, uremia, acromegaly, and pregnancy (Williams and Porte, 1974); evidence for these conditions in our patients was absent. Similar reasoning applies to beta-cell adenoma and beta-cell
Juvenile Familial Hypertriglyceridemia
69
hyperplasia associated with increased insulin secretion. So the reason for hyperinsulinism in our patients at the m o m e n t cannot be elucidated. As has been reported earlier (Ditschuneit et al., 1972) it is not difficult to achieve a decrease of triglyceride values during hospitalization. However, it is not practical to a t t e m p t triglyceride values of less than 800 rag/100 ml on an outpatient basis: unrealistic dietary prescriptions will not be followed and thus inhibit control over the metabolic status. Moreover, there are no reports of statistically significant increases in pancreatitis, a b d o m i n a l colic, or ischemic heart disease when these patients with familial hypertriglyceridemia are monitored on a level of about 800--1000 mg/ 100 ml triglycerides. A further attempt to localize the metabolic defect in our patients with familial hypertriglyceridemia type I in c o m b i n a t i o n with growth retardation and increased glucose assimilation in the adenylcyclase-cyclic A M P - p r o t e i n k i n a s e triglyceridlipase system (Kaukel et al., 1975) has raised the possibility of a defect in this lipolytic cascade. Complete investigations of this point will be reported elsewhere.
References
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Received September 15, 1976
