J. Inher. Metab. Dis. 15 (1992) 416-418 9 SSIEM and Kluwer AcademicPublishers. Printed in the Netherlands
Short Communication
Adenylosuccinase Deficiency: A Newly Recognized Variant J. JAEKEN1, F. VAN DEN BERGH2, M. F. VINCENT2, P. CASAER1 and G. VAN DEN BERGHE2 1Department of Paediatrics, University Hospital Gasthuisberg, Herestraat 49, B-3000 Leuven, Belgium; 2Laboratory of Physiological Chemistry, International Institute of Cellular and Molecular Pathology, Brussels, Belgium Adenylosuccinase deficiency (McKusick 103050) is a genetic defect of de novo purine and AMP synthesis, first reported in 1984 (Jaeken and Van den Berghe 1984) (Figure 1). It results in the accumulation in CSF, plasma and urine of two normally undetectable compounds: succinyladenosine and succinylaminoimidazole carboxamide riboside (SAICA riboside). From a clinical and biochemical study of 8 patients (Jaeken et al 1988), two main subtypes can be distinguished: very severely retarded patients (n = 7) with CSF succinyladenosine ranging from 130 to 170/~mol/L, SAICA
PRPP I I I
vl
Pi
SAICAR
1
2~ ~ SAICAriboside
"~fum
AICAR Pi S-AMP
/ IMP ~
~ S-Ado
(1)~ fum AMP
Figure 1 Pathway of adenine nucleotide synthesis. PRPP, phosphoribosyl pyrophosphate;
SAICAR, succinylaminoimidazole carboxamide ribotide; Pi, inorganic phosphate; fum, fumarate; AICAR, aminoimidazole carboxamide ribotide; IMP, inosine monophosphate; S-AMP, adenylosuccinate; S-Ado, succinyladenosine; AMP, adenosine monophosphate. (1) adenylosuccinase; (2) cytosolic 5'-nucleotidase; (3) aden)(losuccinate synthetase. (From Van den Berg et al 1991, with permission) 416
Adenylosuccinase Deficiency
417
riboside from 90 to 130/~mol/L, and the ratio of succinyladenosine over SAICA riboside between 1 and 2; and a slightly retarded girl with succinyladenosine reaching 475#mol/L, SIACA riboside 128/~mol/L, and the ratio around 4. Some of these patients also have muscle wasting and growth failure, associated with a deficiency of the muscle enzyme. We present a patient with clinical and biochemical features suggestive of a new variant. CASE REPORT
The patient is the only child of healthy, unrelated parents. She was born after a normal term pregnancy. Birthweight was 2000g. Psychomotor development was markedly retarded: sitting at 2.5 years, walking at 3 and speaking a few words at 9. Absences noted at 5 years responded to sodium valproate. At age 12.5 years she was referred for aggressive behaviour. Growth was normal and there was no dysmorphy. Stereotypies were present. Electroencephalography showed a generalized paroxystic activity. CT scan of the brain revealed slightly enlarged ventricles and a large cisterna magna. The Bratton-Marshall test on urine was positive indicating the presence of succinylpurines (in the absence of sulphonamide intake) (Laikind et al 1986). METHODS
Succinylpurines (succinyladenosine and SAICA riboside) were measured in cerebrospinal fluid and urine by high-performance liquid chromatography as described previously (Jaeken and Van den Berghe 1984). Adenylosuccinase activity in fibroblasts was determined by a radiochemical method measuring the release of labelled fumarate from either [~4C]adenylosuccinate or [~4C]succinylaminoimidazole carboxamide ribotide (SAICAR) after its separation from the substrate by chromatography on polyethyleneimine thin-layer plates (Van den Bergh et al 1991). RESULTS
Both succinylpurines were Present in cerebrospinal fluid and urine. In CSF succinyladenosine was 379/zmol/L and SAICA riboside 214/zmol/L (normally undetectable). The ratio of CSF succinyladenosine over SAICA riboside was 1.77. Adenylosuccinase activity in fibroblasts was 0.60nmolmin -1 (rag protein) -1 with adenylosuccinate as substrate (mean __ SEM in 4 controls: 1.40 + 0.08) and 0.28 nmol rain-1 (rag protein)- 1 with SAICA ribotide as substrate (mean _+ SEM in 4 controls 0.90 _+ 0.12). Activities in the father were respectively 110% and 108% of the mean control value, and in the mother 57% and 59%. DISCUSSION This patient differs from the previous ones in a number of ways. In the other patients, except for one child with only mild expression, clinical involvement was extremely severe, particularly regarding psychomotor retardation, epilepsy and autistic features. The present patient clearly has an intermediate degree of symptomatology. J. Inher. Metab. Dis. 15 (1992)
418
daeken et al.
CSF succinyladenosine in the other patients ranged from 126 to 166 #mol/L except for a much higher value in the child with mild clinical features (475 #mol/L). In the present patient this concentration was intermediate while her CSF SAICA riboside concentration was about twice that in the others (median 107, range 91-120). The data in the present patient strengthen our impression that there is an inverse relationship between the degree of clinical involvement and the excess of succinyladenosine over SAICA riboside. It is therefore tempting to conclude that SAICA riboside may be the offending compound which interferes with neural function, and that succinyladenosine could protect against its effects. Fibroblast adenylosuccinase activity with adenylosuccinate (33% of mean control) was within the range found in previously reported patients with severe retardation (30-45%) (Jaeken et al 1988). The present findings add to the heterogeneity of adenylosuccinase deficiency. Therefore, screening for this disorder should be performed systematically not only in severe but also in mild psychomotor retardation whether or not accompanied by epilepsy or behavioural disturbances. For this purpose a modified Bratton-Marshall test (Laikind et al 1986; Van den Berghe and Jaeken 1986) appears most practical (provided the patients do not receive sulphonamides) as well as thin-layer chromatography of imidazole compounds (de Bree et al 1986). Thin-layer chromatography of mono- and disaccharides can also be used for screening purposes and has the advantage of possibly revealing other defects in de novo purine synthesis, since all intermediates of this pathway contain ribose (Jaeken and Van den Berghe 1989). REFERENCES
de Bree PK, Wadman SK, Duran M, Fabery de Jonghe H (1986) Diagnosis of inherited adenylosuccinase deficiency by thin-layer chromatography of urinary imidazoles and by automated cation exchange column chromatography of purines. Clin Chim Acta 156: 279-288. Jaeken J, Van den Berghe G (1984) An infantile autistic syndrome characterised by the presence of succinylpurines in body fluids. Lancet 2: 1058-1061. Jaeken J, Van den Berghe G (1989) Screening for inborn errors of purine synthesis. Lancet 1: 500. Jaeken J, Wadman SK, Duran M et al (1988) Adenylosuccinase deficiency: an inborn error of purine nucleotide synthesis. Eur J Pediatr 148: 126-133. Laikind PK, Seegmiller JE, Gruber HE (1986) Detection of 5'-phosphoribosyl-4-(N-succinylcarboxamide)-5- aminoimidazole in urine by use of the Bratton-Marshall reaction: identification of patients deficient in adenylosuccinate lyase activity. Anal Biochem 156: 81-90. Van den Berghe G, Jaeken J (1986) Use of the Bratton-Marshall test for the diagnosis of adenylosuccinase deficiency (in Dutch). Versl Belg Ver Kindergen 18: 42-46. Van den Berg F, Vincent MF, Jaeken J, Van den Berghe G (1991) Radiochemical assay of adenylosuccinase: demonstration of parallel loss of activity toward both adenylosuccinate and succinylaminoimidazole carboxamide ribotide in liver of patients with the enzyme defect. Anal Biochem 193: 287-291.
J. Inher. Metab. Dis. 15 (1992)
Short Communication
Adenylosuccinase Deficiency: A Newly Recognized Variant J. JAEKEN1, F. VAN DEN BERGH2, M. F. VINCENT2, P. CASAER1 and G. VAN DEN BERGHE2 1Department of Paediatrics, University Hospital Gasthuisberg, Herestraat 49, B-3000 Leuven, Belgium; 2Laboratory of Physiological Chemistry, International Institute of Cellular and Molecular Pathology, Brussels, Belgium Adenylosuccinase deficiency (McKusick 103050) is a genetic defect of de novo purine and AMP synthesis, first reported in 1984 (Jaeken and Van den Berghe 1984) (Figure 1). It results in the accumulation in CSF, plasma and urine of two normally undetectable compounds: succinyladenosine and succinylaminoimidazole carboxamide riboside (SAICA riboside). From a clinical and biochemical study of 8 patients (Jaeken et al 1988), two main subtypes can be distinguished: very severely retarded patients (n = 7) with CSF succinyladenosine ranging from 130 to 170/~mol/L, SAICA
PRPP I I I
vl
Pi
SAICAR
1
2~ ~ SAICAriboside
"~fum
AICAR Pi S-AMP
/ IMP ~
~ S-Ado
(1)~ fum AMP
Figure 1 Pathway of adenine nucleotide synthesis. PRPP, phosphoribosyl pyrophosphate;
SAICAR, succinylaminoimidazole carboxamide ribotide; Pi, inorganic phosphate; fum, fumarate; AICAR, aminoimidazole carboxamide ribotide; IMP, inosine monophosphate; S-AMP, adenylosuccinate; S-Ado, succinyladenosine; AMP, adenosine monophosphate. (1) adenylosuccinase; (2) cytosolic 5'-nucleotidase; (3) aden)(losuccinate synthetase. (From Van den Berg et al 1991, with permission) 416
Adenylosuccinase Deficiency
417
riboside from 90 to 130/~mol/L, and the ratio of succinyladenosine over SAICA riboside between 1 and 2; and a slightly retarded girl with succinyladenosine reaching 475#mol/L, SIACA riboside 128/~mol/L, and the ratio around 4. Some of these patients also have muscle wasting and growth failure, associated with a deficiency of the muscle enzyme. We present a patient with clinical and biochemical features suggestive of a new variant. CASE REPORT
The patient is the only child of healthy, unrelated parents. She was born after a normal term pregnancy. Birthweight was 2000g. Psychomotor development was markedly retarded: sitting at 2.5 years, walking at 3 and speaking a few words at 9. Absences noted at 5 years responded to sodium valproate. At age 12.5 years she was referred for aggressive behaviour. Growth was normal and there was no dysmorphy. Stereotypies were present. Electroencephalography showed a generalized paroxystic activity. CT scan of the brain revealed slightly enlarged ventricles and a large cisterna magna. The Bratton-Marshall test on urine was positive indicating the presence of succinylpurines (in the absence of sulphonamide intake) (Laikind et al 1986). METHODS
Succinylpurines (succinyladenosine and SAICA riboside) were measured in cerebrospinal fluid and urine by high-performance liquid chromatography as described previously (Jaeken and Van den Berghe 1984). Adenylosuccinase activity in fibroblasts was determined by a radiochemical method measuring the release of labelled fumarate from either [~4C]adenylosuccinate or [~4C]succinylaminoimidazole carboxamide ribotide (SAICAR) after its separation from the substrate by chromatography on polyethyleneimine thin-layer plates (Van den Bergh et al 1991). RESULTS
Both succinylpurines were Present in cerebrospinal fluid and urine. In CSF succinyladenosine was 379/zmol/L and SAICA riboside 214/zmol/L (normally undetectable). The ratio of CSF succinyladenosine over SAICA riboside was 1.77. Adenylosuccinase activity in fibroblasts was 0.60nmolmin -1 (rag protein) -1 with adenylosuccinate as substrate (mean __ SEM in 4 controls: 1.40 + 0.08) and 0.28 nmol rain-1 (rag protein)- 1 with SAICA ribotide as substrate (mean _+ SEM in 4 controls 0.90 _+ 0.12). Activities in the father were respectively 110% and 108% of the mean control value, and in the mother 57% and 59%. DISCUSSION This patient differs from the previous ones in a number of ways. In the other patients, except for one child with only mild expression, clinical involvement was extremely severe, particularly regarding psychomotor retardation, epilepsy and autistic features. The present patient clearly has an intermediate degree of symptomatology. J. Inher. Metab. Dis. 15 (1992)
418
daeken et al.
CSF succinyladenosine in the other patients ranged from 126 to 166 #mol/L except for a much higher value in the child with mild clinical features (475 #mol/L). In the present patient this concentration was intermediate while her CSF SAICA riboside concentration was about twice that in the others (median 107, range 91-120). The data in the present patient strengthen our impression that there is an inverse relationship between the degree of clinical involvement and the excess of succinyladenosine over SAICA riboside. It is therefore tempting to conclude that SAICA riboside may be the offending compound which interferes with neural function, and that succinyladenosine could protect against its effects. Fibroblast adenylosuccinase activity with adenylosuccinate (33% of mean control) was within the range found in previously reported patients with severe retardation (30-45%) (Jaeken et al 1988). The present findings add to the heterogeneity of adenylosuccinase deficiency. Therefore, screening for this disorder should be performed systematically not only in severe but also in mild psychomotor retardation whether or not accompanied by epilepsy or behavioural disturbances. For this purpose a modified Bratton-Marshall test (Laikind et al 1986; Van den Berghe and Jaeken 1986) appears most practical (provided the patients do not receive sulphonamides) as well as thin-layer chromatography of imidazole compounds (de Bree et al 1986). Thin-layer chromatography of mono- and disaccharides can also be used for screening purposes and has the advantage of possibly revealing other defects in de novo purine synthesis, since all intermediates of this pathway contain ribose (Jaeken and Van den Berghe 1989). REFERENCES
de Bree PK, Wadman SK, Duran M, Fabery de Jonghe H (1986) Diagnosis of inherited adenylosuccinase deficiency by thin-layer chromatography of urinary imidazoles and by automated cation exchange column chromatography of purines. Clin Chim Acta 156: 279-288. Jaeken J, Van den Berghe G (1984) An infantile autistic syndrome characterised by the presence of succinylpurines in body fluids. Lancet 2: 1058-1061. Jaeken J, Van den Berghe G (1989) Screening for inborn errors of purine synthesis. Lancet 1: 500. Jaeken J, Wadman SK, Duran M et al (1988) Adenylosuccinase deficiency: an inborn error of purine nucleotide synthesis. Eur J Pediatr 148: 126-133. Laikind PK, Seegmiller JE, Gruber HE (1986) Detection of 5'-phosphoribosyl-4-(N-succinylcarboxamide)-5- aminoimidazole in urine by use of the Bratton-Marshall reaction: identification of patients deficient in adenylosuccinate lyase activity. Anal Biochem 156: 81-90. Van den Berghe G, Jaeken J (1986) Use of the Bratton-Marshall test for the diagnosis of adenylosuccinase deficiency (in Dutch). Versl Belg Ver Kindergen 18: 42-46. Van den Berg F, Vincent MF, Jaeken J, Van den Berghe G (1991) Radiochemical assay of adenylosuccinase: demonstration of parallel loss of activity toward both adenylosuccinate and succinylaminoimidazole carboxamide ribotide in liver of patients with the enzyme defect. Anal Biochem 193: 287-291.
J. Inher. Metab. Dis. 15 (1992)
