YMGME-05884; No. of pages: 4; 4C: Molecular Genetics and Metabolism xxx (2015) xxx–xxx
Contents lists available at ScienceDirect
Molecular Genetics and Metabolism journal homepage: www.elsevier.com/locate/ymgme
Delayed diagnosis of late-onset Pompe disease in patients with myopathies of unknown origin and/or hyperCKemia Jordi Pérez-López a,⁎, Albert Selva-O'Callaghan a, Josep M. Grau-Junyent b, Luis Gallego-Galindo a, M. Josep Coll c, Salvador García-Morillo d, Miguel A. Torralba-Cabeza e, Miquel Vilardell-Tarrés a a
Department of Internal Medicine, Hospital Vall d'Hebron, 119-129, 08035, Barcelona, Spain Department of Internal Medicine, Hospital Clínic, Carrer Villarroel, 170, 08036, Barcelona, Spain Department of Biochemistry and Molecular Genetics, Hospital Clínic, Carrer Villarroel, 170, 08036, Barcelona, Spain d Department of Internal Medicine, Hospital Virgen del Rocío, Avenida Manuel Siurot, s/n, 41013, Sevilla, Spain e Department of Internal Medicine, Hospital Lozano Blesa, Avenida San Juan Bosco, 15, 50009 Zaragoza, Spain b c
a r t i c l e
i n f o
Article history: Received 12 January 2015 Received in revised form 14 February 2015 Accepted 14 February 2015 Available online xxxx Keywords: Alpha glucosidase Idiopathic hyperCKemia Maltase deficiency Myopathy Pompe disease
a b s t r a c t Pompe disease is a rare metabolic myopathy whose diagnosis is sometimes delayed despite being essential for improving clinical outcomes. We aimed to investigate the prevalence of late-onset Pompe disease among patients with a myopathy of unknown etiology, including polymyositis, or with idiopathic rise of creatine kinase (CK) levels, in a department of internal medicine. A cohort study was conducted in 241 subjects: 140 patients with myopathies of unknown origin or increased CK levels, 30 with polymyositis and 71 who constituted the control group of other myopathies. Acid α-glucosidase (GAA) activity was tested in dried blood spots. If a positive result was obtained, GAA activity in isolated lymphocytes and/or genetic testing was performed as a confirmatory diagnosis. Out of the 140 investigated patients, 2 patients with myopathies of unknown origin were confirmed to be positive for Pompe disease. Thus, late-onset Pompe disease should be considered among adult patients with myopathy of unknown origin. © 2015 Elsevier Inc. All rights reserved.
1. Introduction
1.2. Enzyme replacement therapy (ERT)
1.1. Natural history of Pompe disease
Even though this disease is not curable, the approval in 2006 of enzyme replacement therapy (ERT) with recombinant human acid αglucosidase (rhGAA), alglucosidase alfa, has shown the potential to substantially alter its prognosis. In patients with classic infantile Pompe disease, cardiorespiratory failure is the primary cause of mortality, typically occurring within the first year of life [4]. With the introduction of ERT, survival in patients with classic infantile Pompe disease has increased significantly and the oldest infants treated with rhGAA are now more than 14 years of age [5]. ERT trials in adults were initiated much later than those in infants and, since 2006, several studies have shown the improvement in walking distance on the six-minute walking test and the stabilization of pulmonary function [6–12]. Recently, Gungor et al. demonstrated a beneficial effect of ERT on survival in adults with this disease, likely related to its positive effect on pulmonary function [13].
Pompe disease (glycogen storage disease type II or acid maltase deficiency) is a rare metabolic myopathy caused by a deficiency of the lysosomal enzyme GAA activity resulting in an accumulation of glycogen in the muscle. It is inherited in an autosomal recessive manner, and presents with a heterogeneous array of signs and symptoms including proximal muscle weakness, respiratory insufficiency, and elevated CK levels [1,2]. The rapid clinical decline in classic infantile Pompe disease is explained by the complete lack of GAA activity, but the majority of patients with late-onset Pompe disease express some residual GAA activity, leading to a wide spectrum of clinical presentations. In this clinical form, the disease progresses more slowly, and in some cases, patients develop wheelchair and respirator dependency in later stages of the disease [3]. ⁎ Corresponding author at: Department of Internal Medicine, Hospital Vall d'Hebron, Barcelona, Spain. E-mail addresses: [email protected] (J. Pérez-López), [email protected] (A. Selva-O'Callaghan), [email protected] (J.M. Grau-Junyent), [email protected] (L. Gallego-Galindo), [email protected] (M.J. Coll), [email protected] (S. García-Morillo), [email protected] (M.A. Torralba-Cabeza), [email protected] (M. Vilardell-Tarrés).
1.3. Misdiagnosis of Pompe disease and study aim Nevertheless, late-onset Pompe disease has sometimes been misdiagnosed as limb girdle muscular dystrophy, Duchenne muscular dystrophy or polymyositis, since it mimics other neuromuscular disorders, making its diagnosis challenging and often significantly delayed,
http://dx.doi.org/10.1016/j.ymgme.2015.02.004 1096-7192/© 2015 Elsevier Inc. All rights reserved.
Please cite this article as: J. Pérez-López, et al., Delayed diagnosis of late-onset Pompe disease in patients with myopathies of unknown origin and/ or hyperCKemia, Mol. Genet. Metab. (2015), http://dx.doi.org/10.1016/j.ymgme.2015.02.004
2
J. Pérez-López et al. / Molecular Genetics and Metabolism xxx (2015) xxx–xxx
Fig. 1. Flow chart.
and thereby, increasing morbidity and early mortality of the disease [1,2]. This fact prompted the present study whose main objective was to investigate the prevalence of Pompe disease in a cohort of adult patients with a myopathy of unknown etiology or an idiopathic rise in creatine kinase levels, and seen in the department of Internal Medicine of several different tertiary hospitals in Spain.
by fluorimetry in mixed leucocytes derived from DBS on filter paper, using 4-methylumbelliferyl α-D-glucopyranoside as a substrate, and a specific inhibitor (acarbose) to eliminate the interference with neutral α-glucosidases, according to the methodology previously described [14]. If a positive result was obtained, GAA activity in isolated lymphocytes and/or genetic testing was performed as a confirmatory diagnosis using standard protocols [15].
2. Patients and methods 2.1. Patients sample This was a cohort-study including every patient who was seen in the department of internal medicine at four Spanish referral teaching hospitals over the past 15 years and who presented with either myopathy of unknown origin or polymyositis. In addition, and as a second group, we prospectively included every patient from the mentioned departments (from March 1, 2012 to February 1, 2014) with increased CK levels (at least three times the normal value) as the only sign, and without a definite diagnosis. Finally we included another group of patients with well-known myopathies (such as dermatomyositis, dystrophinopathies, dysferlinopathies, mitochondrial myopathies, and McArdle disease) as a control group in order to study the specificity of GAA activity on dried blood spots (DBS). 2.2. Diagnostic methods The diagnosis of both, polymyositis and myopathy of unknown origin, was reached after a full routine histopathologic analysis performed on muscle biopsies. Briefly, surgical muscle biopsies were immediately frozen in cooled 2-metyl-buthan, cryotom sectioned, and submitted to the following stains and reactions: hematoxylin-eosin, Gomori's trichrome, non-specific esterase, periodic acid-Schiff's, acid phosphatase, myophosphorilase, oil red-O, nicotinamide adenine dinucleotide diaphorase protocol (NADH-TR), succinic dehydrogenase, cytochrome oxidase and adenosine triphosphatase at three different pH. Additional histochemistry (myoadenilate-deaminase or Congo Red) and immunohistochemistry reactions (CD3, CD20, CD 68, class I antigen from the major histocompatibility complex, or sarcoplasmic proteins) were performed only when considered necessary. The first-line diagnostic procedure for Pompe disease was performed for all study patients, who were, therefore, recalled for a blood draw, after written informed consent. GAA activity was tested
2.3. Statistical analysis and ethical standards All data were analyzed using the statistics program SPSS for Windows version 17.0 (SPSS Inc., Chicago, IL). For the quantitative variables, the mean was calculated as a measure of central tendency and standard deviation (SD) as a measure of statistical dispersion. The study was performed in accord with the standards of the Ethics Committee of Hospital Vall d'Hebron, Barcelona, and in accord with the Helsinki Declaration of 1975. 3. Results 3.1. Patients characteristics The study included a total of 241 patients (45% male), with a mean age of 53.6 (SD 17.6) years, of which, 62 patients constituted the group of myopathy of unknown origin, 78 the group of increased CK levels, 30 the group of polymyositis and 71 the control group of other myopathies. The patients' flow chart is shown in Fig. 1. Most patients with myopathy of unknown origin presented proximal muscular weakness, predominantly in the pelvic girdle. And the average value of CK levels in patients from the second group was 956 (SD 250) UI/L (range 450–10,000 UI/L). 3.2. Dried blood spot (DBS) results Only three patients (2 with myopathy of unknown origin and 1 with polymyositis) showed a significantly decreased activity of GAA in dried blood spot. Nevertheless, GAA activity in isolated lymphocytes was within the control range in the patient with polymyositis, and thus, late-onset Pompe disease was discarded. The two patients with myopathy of unknown origin were confirmed to be positive for Pompe disease, one by enzymatic testing and the other one by genetic testing.
Please cite this article as: J. Pérez-López, et al., Delayed diagnosis of late-onset Pompe disease in patients with myopathies of unknown origin and/ or hyperCKemia, Mol. Genet. Metab. (2015), http://dx.doi.org/10.1016/j.ymgme.2015.02.004
J. Pérez-López et al. / Molecular Genetics and Metabolism xxx (2015) xxx–xxx
3.3. Pompe cases The description of these two confirmed Pompe patients is as follows: Patient 1: A 63-year-old woman diagnosed of limb girdle muscle dystrophy when she was 37. At the time of inclusion in the current study and on musculoskeletal examination, she presented a reduction of proximal muscle strength in arms and lower limbs, and a myopathic gait. Over time she further complained of episodes of dysphagia to solids and liquids and dyspnea on exercise. Her pulmonary function tests revealed a FEV1 (forced expiratory volume in 1 s) of 36% predicted and a FVC (forced vital capacity) of 38% predicted. Electromyography showed a diffuse irritable myopathic process. Biochemical parameters showed CK levels of 133 UI/L (normal range 17–176). When muscle biopsy (performed in left quadriceps femoris muscle) was reviewed, only a mild increase in the activity of acid phosphatase was noticed, without glycogen storage or other abnormalities. Activity of GAA in dried blood spot was 0.20 nmol/ 21 h × spot (normal range: 0.31–3.31 nmol/21 h × spot). Confirmation of Pompe diagnosis was obtained measuring the activity of αglucosidase in lymphocytes. The result obtained was 2 nmol/ h × mg protein (normal range: 6–32 nmol/h × mg protein). Patient 2: A 61-year-old woman presenting with a progressively increasing weakness for the past 9 years. At the time of diagnosis and on musculoskeletal examination she presented a reduction of proximal muscle strength in arms and lower limbs. Tone and deep tendon reflexes were normal. Her pulmonary function tests revealed a FEV1 of 44% predicted and a FVC of 43% predicted. Electromyography showed a diffuse irritable myopathic process. Biochemical parameters showed CK levels of 450 UI/L (normal range 17–176). Immunological work-up in blood serum by enzyme-linked immunosorbent assay revealed the presence of anti-nuclear anti-bodies at a titer of 1:160 and anti-Ro antibodies at a titer of 1:40. Polymyositis was suspected and glucocorticoids treatment was taken under consideration, but the muscle biopsy taken from the left biceps did not revealed abnormal findings. Activity of GAA in dried blood spot was 0.21 nmol/21 h × spot (normal range: 0.31–3.31 nmol/ 21 h × spot). Activity of α-glucosidase in lymphocytes was 0.09 nmol/min/mg prot (normal range 0.15–0.9 nmol/min/mg prot) and gene mutation analysis revealed two changes, c.896 T N C and c.2481 + 102_2646 + 31del. ERT with alglucosidase alpha was considered and nowadays both patients are under treatment. 4. Discussion Our patients have a very long history of progressive skeletal muscle weakness, and other diagnosis was contemplated before the final diagnosis of late-onset Pompe disease. Even though the greatest increase of CK levels in blood serum is found in infantile onset patients (as high as 2000 UI/L), approximately 95% of late onset patients have an elevated CK levels [16,17]. However, as occurs in our described patients, some adults with Pompe disease may have CK levels within the normal reference range or very mildly raised, especially in those with long standing evolution [17]. None presented histological findings consistent with glycogen storage disease. In late-onset Pompe disease, the site of muscle biopsy can impact results due to the variability of glycogen accumulation both between different muscles and between the muscle fiber types within a muscle [16]. Thus, experience has shown that relying solely on visualizing a periodic acid-Schiff (PAS) positive vacuolar myopathy to identify late-onset Pompe disease often leads to false-negative results, and
3
subsequently delays diagnosis and treatment of the disorder. In adult but not infant patients with Pompe disease, muscle ultrasound might be used to aid the diagnosis {Vill, 2015 #107}, and to avoid falsenegative results based on non-presence of Pompe-associated histological findings. Pompe patients have been shown to have at least one abnormal muscle among the following: elbow flexors, triceps brachii, extensor carpi radialis, rectus femoris, and tibialis anterior, with a particular pattern of muscle involvement in which, tríceps brachii is usually spared, as compared to patients with other myopathies {Zaidman, 2011 #106}. Thus, in case of negative biopsy results, muscular ultrasound might add strength to this finding and to the probability of not being Pompe disease, or otherwise, lead to further diagnostic tests. In addition, although histologic examination in Pompe disease reveals mostly a mild vacuolar myopathy typical of glycogen accumulation within skeletal and smooth muscle cells, it can also show a chronic myositis with degenerating and regenerating muscle fibers [18], which can contribute to a mistaken polymyositis diagnosis (as was the case of our second patient). Polymyositis and other idiopathic inflammatory myopathies have been questioned by some authors [19], arguing that they are just diagnosis of exclusion. As a consequence, in order to make the diagnosis of polymyositis, a list of other diseases such as hypothyroidism myopathy, dystrophinopathies, and dysferlinopathies should be excluded. In our opinion, if diagnosis of polymyositis is suspected but muscle biopsy does not support that diagnosis, Pompe disease should be added to the exclusion list prior to concluding onto a diagnosis of polymyositis. Regarding the DBS test, some studies reported a sensitivity and specificity of almost 100% for the identification of Pompe-affected individuals among pediatric populations [20,21]. Although the negative predicted value of DBS for diagnosing Pompe disease, observed in our control group with well-known myopathies, was 100%, one patient with polymyositis showed decreased GAA activity in dried blood spots that was not confirmed when the enzyme activity was assessed in isolated lymphocytes. Although the DBS test is valid for the screening of Pompe disease in non-newborn patients, enzyme activities in DBS have been shown to be significantly lower in adult individuals{Brand, 2013 #105}, which might explain the low GAA activity observed in the false positive polymyositis patient. Further studies addressed to clarify the sensitivity and specificity of the test in adults are needed, and by the moment, confirmatory analysis of low GAA activity determined by DBS in adults by means of isolated activity in peripheral blood lymphocytes and/or genetic testing is mandatory. Previous studies have shown patients with Pompe, based on DBS test results, among patients with unclassified limb-girdle muscular dystrophies [22], and among patients with hyperCKmeia [23]. The mentioned studied series were short and thus, the current study adds on evidence to previous results regarding unclassified myopathies. One major limitation of the study is its non-prospective design, which might lead to bias. Thus we could not talk about true prevalence of Pompe in patients with undiagnosed myopathies and/or hyperCKemia. However, taken the data obtained, we could still conclude that some of these patients, at least those with myopathies, are undiagnosed Pompe cases. Further prospective studies nation-wide should be performed to establish the prevalence of Pompe among these patients in the Spanish population. 4.1. Conclusions Two out of 62 patients with unclassified myopathies were diagnosed with Pompe disease. Neither one presented histological findings consistent with glycogen storage disease, confirming that relying solely on biopsy data often leads to false-negative results. One patient diagnosed with polymyositis provided an example of a false positive result, showing decreased GAA activity in DBS, which was not confirmed in isolated lymphocytes,
Please cite this article as: J. Pérez-López, et al., Delayed diagnosis of late-onset Pompe disease in patients with myopathies of unknown origin and/ or hyperCKemia, Mol. Genet. Metab. (2015), http://dx.doi.org/10.1016/j.ymgme.2015.02.004
4
J. Pérez-López et al. / Molecular Genetics and Metabolism xxx (2015) xxx–xxx
stressing the importance of diagnosis confirmation after DBS positive results. Diagnosis of late-onset Pompe disease should be considered among patients with myopathy of unknown origin, a group of patients where the diagnosis of this disease is often delayed. Conflict of interest disclosures Jordi Pérez-López and Miguel A Torralba-Cabeza have received honoraria from Genzyme as advisory board members. Acknowledgments Funding sources for the logistical support of this study were provided by Genzyme, a Sanofi company (Sanofi-Aventis, S.A., Spain). Study ClinicalTrials.gov identifier: NCT01482494. Almudena PardoMateos provided editorial support, which was funded by Genzyme Corporation, and a Sanofi company. References [1] R. Hirschhorn, A.J. Reuser, Glycogen storage disease type II: acid alphaglucosidase (acid maltase) deficiency, in: B.A. Scriver, W. Sly, D. Valle (Eds.), The Metabolic and Molecular Bases of Inherited Disease, 8th ed.McGraw-Hill, New York, 2001, pp. 3389–3420. [2] A.T. van der Ploeg, A.J. Reuser, Pompe's disease, Lancet 372 (9646) (Oct 11 2008) 1342–1353. [3] A. Engel, R. Hirschhorn, M.L. Huie, Acid maltase deficiency, in: E. AF-AC (Ed.), Myology, 3rd ed.McGraw-Hill, New York, 2004. [4] P.S. Kishnani, D. Corzo, N.D. Leslie, et al., Early treatment with alglucosidase alpha prolongs long-term survival of infants with Pompe disease, Pediatr. Res. 66 (3) (Sep 2009) 329–335. [5] C.M. van Gelder, C.I. van Capelle, B.J. Ebbink, et al., Facial-muscle weakness, speech disorders and dysphagia are common in patients with classic infantile Pompe disease treated with enzyme therapy, J. Inherit. Metab. Dis. 35 (3) (May 2012) 505–511. [6] J.M. de Vries, N.A. van der Beek, W.C. Hop, et al., Effect of enzyme therapy and prognostic factors in 69 adults with Pompe disease: an open-label single-center study, Orphanet J. Rare Dis. 7 (2012) 73. [7] S. Strothotte, N. Strigl-Pill, B. Grunert, et al., Enzyme replacement therapy with alglucosidase alfa in 44 patients with late-onset glycogen storage disease type 2: 12-month results of an observational clinical trial, J. Neurol. 257 (1) (Jan 2010) 91–97.
[8] B. Bembi, F.E. Pisa, M. Confalonieri, et al., Long-term observational, non-randomized study of enzyme replacement therapy in late-onset glycogenosis type II, J. Inherit. Metab. Dis. 33 (6) (Dec 2010) 727–735. [9] C. Angelini, C. Semplicini, S. Ravaglia, et al., Observational clinical study in juvenileadult glycogenosis type 2 patients undergoing enzyme replacement therapy for up to 4 years, J. Neurol. 259 (5) (May 2012) 952–958. [10] D. Orlikowski, N. Pellegrini, H. Prigent, et al., Recombinant human acid alphaglucosidase (rhGAA) in adult patients with severe respiratory failure due to Pompe disease, Neuromuscul. Disord. 21 (7) (Jul 2011) 477–482. [11] C. Regnery, C. Kornblum, F. Hanisch, et al., 36 months observational clinical study of 38 adult Pompe disease patients under alglucosidase alfa enzyme replacement therapy, J. Inherit. Metab. Dis. 35 (5) (Sep 2012) 837–845. [12] A.T. van der Ploeg, P.R. Clemens, D. Corzo, et al., A randomized study of alglucosidase alfa in late-onset Pompe's disease, N. Engl. J. Med. 362 (15) (Apr 15 2010) 1396–1406. [13] D. Gungor, M.E. Kruijshaar, I. Plug, et al., Impact of enzyme replacement therapy on survival in adults with Pompe disease: results from a prospective international observational study, Orphanet J. Rare Dis. 8 (1) (Mar 27 2013) 49. [14] Z. Lukacs, P. Nieves Cobos, E. Mengel, et al., Diagnostic efficacy of the fluorometric determination of enzyme activity for Pompe disease from dried blood specimens compared with lymphocytes-possibility for newborn screening, J. Inherit. Metab. Dis. 33 (1) (Feb 2010) 43–50. [15] L. Gort, M.J. Coll, A. Chabas, Glycogen storage disease type II in Spanish patients: high frequency of c.1076-1G N C mutation, Mol. Genet. Metab. 92 (1–2) (Sep-Oct 2007) 183–187. [16] P.S. Kishnani, R.D. Steiner, D. Bali, et al., Pompe disease diagnosis and management guideline, Genet. Med. 8 (5) (May 2006) 267–288. [17] M.G. Ausems, P. Lochman, O.P. van Diggelen, et al., A diagnostic protocol for adultonset glycogen storage disease type II, Neurology 52 (4) (Mar 10 1999) 851–853. [18] L.D. Hobson-Webb, A.D. Proia, B.L. Thurberg, et al., Autopsy findings in late-onset Pompe disease: a case report and systematic review of the literature, Mol. Genet. Metab. 106 (4) (Aug 2012) 462–469. [19] A.A. Amato, R.C. Griggs, Unicorns, dragons, polymyositis, and other mythological beasts, Neurology 61 (3) (Aug 12 2003) 288–289. [20] K. Umapathysivam, J.J. Hopwood, P.J. Meikle, Determination of acid alphaglucosidase activity in blood spots as a diagnostic test for Pompe disease, Clin. Chem. 47 (8) (Aug 2001) 1378–1383. [21] Pompe Disease Diagnostic Working G, B. Winchester, D. Bali, et al., Methods for a prompt and reliable laboratory diagnosis of Pompe disease: report from an international consensus meeting, Mol. Genet. Metab. 93 (3) (Mar 2008) 275–281. [22] N. Preisler, Z. Lukacs, L. Vinge, et al., Late-onset Pompe disease is prevalent in unclassified limb-girdle muscular dystrophies, Mol. Genet. Metab. 110 (3) (Nov 2013) 287–289. [23] M. Spada, F. Porta, L. Vercelli, et al., Screening for later-onset Pompe's disease in patients with paucisymptomatic hyperCKemia, Mol. Genet. Metab. 109 (2) (Jun 2013) 171–173.
Please cite this article as: J. Pérez-López, et al., Delayed diagnosis of late-onset Pompe disease in patients with myopathies of unknown origin and/ or hyperCKemia, Mol. Genet. Metab. (2015), http://dx.doi.org/10.1016/j.ymgme.2015.02.004
Contents lists available at ScienceDirect
Molecular Genetics and Metabolism journal homepage: www.elsevier.com/locate/ymgme
Delayed diagnosis of late-onset Pompe disease in patients with myopathies of unknown origin and/or hyperCKemia Jordi Pérez-López a,⁎, Albert Selva-O'Callaghan a, Josep M. Grau-Junyent b, Luis Gallego-Galindo a, M. Josep Coll c, Salvador García-Morillo d, Miguel A. Torralba-Cabeza e, Miquel Vilardell-Tarrés a a
Department of Internal Medicine, Hospital Vall d'Hebron, 119-129, 08035, Barcelona, Spain Department of Internal Medicine, Hospital Clínic, Carrer Villarroel, 170, 08036, Barcelona, Spain Department of Biochemistry and Molecular Genetics, Hospital Clínic, Carrer Villarroel, 170, 08036, Barcelona, Spain d Department of Internal Medicine, Hospital Virgen del Rocío, Avenida Manuel Siurot, s/n, 41013, Sevilla, Spain e Department of Internal Medicine, Hospital Lozano Blesa, Avenida San Juan Bosco, 15, 50009 Zaragoza, Spain b c
a r t i c l e
i n f o
Article history: Received 12 January 2015 Received in revised form 14 February 2015 Accepted 14 February 2015 Available online xxxx Keywords: Alpha glucosidase Idiopathic hyperCKemia Maltase deficiency Myopathy Pompe disease
a b s t r a c t Pompe disease is a rare metabolic myopathy whose diagnosis is sometimes delayed despite being essential for improving clinical outcomes. We aimed to investigate the prevalence of late-onset Pompe disease among patients with a myopathy of unknown etiology, including polymyositis, or with idiopathic rise of creatine kinase (CK) levels, in a department of internal medicine. A cohort study was conducted in 241 subjects: 140 patients with myopathies of unknown origin or increased CK levels, 30 with polymyositis and 71 who constituted the control group of other myopathies. Acid α-glucosidase (GAA) activity was tested in dried blood spots. If a positive result was obtained, GAA activity in isolated lymphocytes and/or genetic testing was performed as a confirmatory diagnosis. Out of the 140 investigated patients, 2 patients with myopathies of unknown origin were confirmed to be positive for Pompe disease. Thus, late-onset Pompe disease should be considered among adult patients with myopathy of unknown origin. © 2015 Elsevier Inc. All rights reserved.
1. Introduction
1.2. Enzyme replacement therapy (ERT)
1.1. Natural history of Pompe disease
Even though this disease is not curable, the approval in 2006 of enzyme replacement therapy (ERT) with recombinant human acid αglucosidase (rhGAA), alglucosidase alfa, has shown the potential to substantially alter its prognosis. In patients with classic infantile Pompe disease, cardiorespiratory failure is the primary cause of mortality, typically occurring within the first year of life [4]. With the introduction of ERT, survival in patients with classic infantile Pompe disease has increased significantly and the oldest infants treated with rhGAA are now more than 14 years of age [5]. ERT trials in adults were initiated much later than those in infants and, since 2006, several studies have shown the improvement in walking distance on the six-minute walking test and the stabilization of pulmonary function [6–12]. Recently, Gungor et al. demonstrated a beneficial effect of ERT on survival in adults with this disease, likely related to its positive effect on pulmonary function [13].
Pompe disease (glycogen storage disease type II or acid maltase deficiency) is a rare metabolic myopathy caused by a deficiency of the lysosomal enzyme GAA activity resulting in an accumulation of glycogen in the muscle. It is inherited in an autosomal recessive manner, and presents with a heterogeneous array of signs and symptoms including proximal muscle weakness, respiratory insufficiency, and elevated CK levels [1,2]. The rapid clinical decline in classic infantile Pompe disease is explained by the complete lack of GAA activity, but the majority of patients with late-onset Pompe disease express some residual GAA activity, leading to a wide spectrum of clinical presentations. In this clinical form, the disease progresses more slowly, and in some cases, patients develop wheelchair and respirator dependency in later stages of the disease [3]. ⁎ Corresponding author at: Department of Internal Medicine, Hospital Vall d'Hebron, Barcelona, Spain. E-mail addresses: [email protected] (J. Pérez-López), [email protected] (A. Selva-O'Callaghan), [email protected] (J.M. Grau-Junyent), [email protected] (L. Gallego-Galindo), [email protected] (M.J. Coll), [email protected] (S. García-Morillo), [email protected] (M.A. Torralba-Cabeza), [email protected] (M. Vilardell-Tarrés).
1.3. Misdiagnosis of Pompe disease and study aim Nevertheless, late-onset Pompe disease has sometimes been misdiagnosed as limb girdle muscular dystrophy, Duchenne muscular dystrophy or polymyositis, since it mimics other neuromuscular disorders, making its diagnosis challenging and often significantly delayed,
http://dx.doi.org/10.1016/j.ymgme.2015.02.004 1096-7192/© 2015 Elsevier Inc. All rights reserved.
Please cite this article as: J. Pérez-López, et al., Delayed diagnosis of late-onset Pompe disease in patients with myopathies of unknown origin and/ or hyperCKemia, Mol. Genet. Metab. (2015), http://dx.doi.org/10.1016/j.ymgme.2015.02.004
2
J. Pérez-López et al. / Molecular Genetics and Metabolism xxx (2015) xxx–xxx
Fig. 1. Flow chart.
and thereby, increasing morbidity and early mortality of the disease [1,2]. This fact prompted the present study whose main objective was to investigate the prevalence of Pompe disease in a cohort of adult patients with a myopathy of unknown etiology or an idiopathic rise in creatine kinase levels, and seen in the department of Internal Medicine of several different tertiary hospitals in Spain.
by fluorimetry in mixed leucocytes derived from DBS on filter paper, using 4-methylumbelliferyl α-D-glucopyranoside as a substrate, and a specific inhibitor (acarbose) to eliminate the interference with neutral α-glucosidases, according to the methodology previously described [14]. If a positive result was obtained, GAA activity in isolated lymphocytes and/or genetic testing was performed as a confirmatory diagnosis using standard protocols [15].
2. Patients and methods 2.1. Patients sample This was a cohort-study including every patient who was seen in the department of internal medicine at four Spanish referral teaching hospitals over the past 15 years and who presented with either myopathy of unknown origin or polymyositis. In addition, and as a second group, we prospectively included every patient from the mentioned departments (from March 1, 2012 to February 1, 2014) with increased CK levels (at least three times the normal value) as the only sign, and without a definite diagnosis. Finally we included another group of patients with well-known myopathies (such as dermatomyositis, dystrophinopathies, dysferlinopathies, mitochondrial myopathies, and McArdle disease) as a control group in order to study the specificity of GAA activity on dried blood spots (DBS). 2.2. Diagnostic methods The diagnosis of both, polymyositis and myopathy of unknown origin, was reached after a full routine histopathologic analysis performed on muscle biopsies. Briefly, surgical muscle biopsies were immediately frozen in cooled 2-metyl-buthan, cryotom sectioned, and submitted to the following stains and reactions: hematoxylin-eosin, Gomori's trichrome, non-specific esterase, periodic acid-Schiff's, acid phosphatase, myophosphorilase, oil red-O, nicotinamide adenine dinucleotide diaphorase protocol (NADH-TR), succinic dehydrogenase, cytochrome oxidase and adenosine triphosphatase at three different pH. Additional histochemistry (myoadenilate-deaminase or Congo Red) and immunohistochemistry reactions (CD3, CD20, CD 68, class I antigen from the major histocompatibility complex, or sarcoplasmic proteins) were performed only when considered necessary. The first-line diagnostic procedure for Pompe disease was performed for all study patients, who were, therefore, recalled for a blood draw, after written informed consent. GAA activity was tested
2.3. Statistical analysis and ethical standards All data were analyzed using the statistics program SPSS for Windows version 17.0 (SPSS Inc., Chicago, IL). For the quantitative variables, the mean was calculated as a measure of central tendency and standard deviation (SD) as a measure of statistical dispersion. The study was performed in accord with the standards of the Ethics Committee of Hospital Vall d'Hebron, Barcelona, and in accord with the Helsinki Declaration of 1975. 3. Results 3.1. Patients characteristics The study included a total of 241 patients (45% male), with a mean age of 53.6 (SD 17.6) years, of which, 62 patients constituted the group of myopathy of unknown origin, 78 the group of increased CK levels, 30 the group of polymyositis and 71 the control group of other myopathies. The patients' flow chart is shown in Fig. 1. Most patients with myopathy of unknown origin presented proximal muscular weakness, predominantly in the pelvic girdle. And the average value of CK levels in patients from the second group was 956 (SD 250) UI/L (range 450–10,000 UI/L). 3.2. Dried blood spot (DBS) results Only three patients (2 with myopathy of unknown origin and 1 with polymyositis) showed a significantly decreased activity of GAA in dried blood spot. Nevertheless, GAA activity in isolated lymphocytes was within the control range in the patient with polymyositis, and thus, late-onset Pompe disease was discarded. The two patients with myopathy of unknown origin were confirmed to be positive for Pompe disease, one by enzymatic testing and the other one by genetic testing.
Please cite this article as: J. Pérez-López, et al., Delayed diagnosis of late-onset Pompe disease in patients with myopathies of unknown origin and/ or hyperCKemia, Mol. Genet. Metab. (2015), http://dx.doi.org/10.1016/j.ymgme.2015.02.004
J. Pérez-López et al. / Molecular Genetics and Metabolism xxx (2015) xxx–xxx
3.3. Pompe cases The description of these two confirmed Pompe patients is as follows: Patient 1: A 63-year-old woman diagnosed of limb girdle muscle dystrophy when she was 37. At the time of inclusion in the current study and on musculoskeletal examination, she presented a reduction of proximal muscle strength in arms and lower limbs, and a myopathic gait. Over time she further complained of episodes of dysphagia to solids and liquids and dyspnea on exercise. Her pulmonary function tests revealed a FEV1 (forced expiratory volume in 1 s) of 36% predicted and a FVC (forced vital capacity) of 38% predicted. Electromyography showed a diffuse irritable myopathic process. Biochemical parameters showed CK levels of 133 UI/L (normal range 17–176). When muscle biopsy (performed in left quadriceps femoris muscle) was reviewed, only a mild increase in the activity of acid phosphatase was noticed, without glycogen storage or other abnormalities. Activity of GAA in dried blood spot was 0.20 nmol/ 21 h × spot (normal range: 0.31–3.31 nmol/21 h × spot). Confirmation of Pompe diagnosis was obtained measuring the activity of αglucosidase in lymphocytes. The result obtained was 2 nmol/ h × mg protein (normal range: 6–32 nmol/h × mg protein). Patient 2: A 61-year-old woman presenting with a progressively increasing weakness for the past 9 years. At the time of diagnosis and on musculoskeletal examination she presented a reduction of proximal muscle strength in arms and lower limbs. Tone and deep tendon reflexes were normal. Her pulmonary function tests revealed a FEV1 of 44% predicted and a FVC of 43% predicted. Electromyography showed a diffuse irritable myopathic process. Biochemical parameters showed CK levels of 450 UI/L (normal range 17–176). Immunological work-up in blood serum by enzyme-linked immunosorbent assay revealed the presence of anti-nuclear anti-bodies at a titer of 1:160 and anti-Ro antibodies at a titer of 1:40. Polymyositis was suspected and glucocorticoids treatment was taken under consideration, but the muscle biopsy taken from the left biceps did not revealed abnormal findings. Activity of GAA in dried blood spot was 0.21 nmol/21 h × spot (normal range: 0.31–3.31 nmol/ 21 h × spot). Activity of α-glucosidase in lymphocytes was 0.09 nmol/min/mg prot (normal range 0.15–0.9 nmol/min/mg prot) and gene mutation analysis revealed two changes, c.896 T N C and c.2481 + 102_2646 + 31del. ERT with alglucosidase alpha was considered and nowadays both patients are under treatment. 4. Discussion Our patients have a very long history of progressive skeletal muscle weakness, and other diagnosis was contemplated before the final diagnosis of late-onset Pompe disease. Even though the greatest increase of CK levels in blood serum is found in infantile onset patients (as high as 2000 UI/L), approximately 95% of late onset patients have an elevated CK levels [16,17]. However, as occurs in our described patients, some adults with Pompe disease may have CK levels within the normal reference range or very mildly raised, especially in those with long standing evolution [17]. None presented histological findings consistent with glycogen storage disease. In late-onset Pompe disease, the site of muscle biopsy can impact results due to the variability of glycogen accumulation both between different muscles and between the muscle fiber types within a muscle [16]. Thus, experience has shown that relying solely on visualizing a periodic acid-Schiff (PAS) positive vacuolar myopathy to identify late-onset Pompe disease often leads to false-negative results, and
3
subsequently delays diagnosis and treatment of the disorder. In adult but not infant patients with Pompe disease, muscle ultrasound might be used to aid the diagnosis {Vill, 2015 #107}, and to avoid falsenegative results based on non-presence of Pompe-associated histological findings. Pompe patients have been shown to have at least one abnormal muscle among the following: elbow flexors, triceps brachii, extensor carpi radialis, rectus femoris, and tibialis anterior, with a particular pattern of muscle involvement in which, tríceps brachii is usually spared, as compared to patients with other myopathies {Zaidman, 2011 #106}. Thus, in case of negative biopsy results, muscular ultrasound might add strength to this finding and to the probability of not being Pompe disease, or otherwise, lead to further diagnostic tests. In addition, although histologic examination in Pompe disease reveals mostly a mild vacuolar myopathy typical of glycogen accumulation within skeletal and smooth muscle cells, it can also show a chronic myositis with degenerating and regenerating muscle fibers [18], which can contribute to a mistaken polymyositis diagnosis (as was the case of our second patient). Polymyositis and other idiopathic inflammatory myopathies have been questioned by some authors [19], arguing that they are just diagnosis of exclusion. As a consequence, in order to make the diagnosis of polymyositis, a list of other diseases such as hypothyroidism myopathy, dystrophinopathies, and dysferlinopathies should be excluded. In our opinion, if diagnosis of polymyositis is suspected but muscle biopsy does not support that diagnosis, Pompe disease should be added to the exclusion list prior to concluding onto a diagnosis of polymyositis. Regarding the DBS test, some studies reported a sensitivity and specificity of almost 100% for the identification of Pompe-affected individuals among pediatric populations [20,21]. Although the negative predicted value of DBS for diagnosing Pompe disease, observed in our control group with well-known myopathies, was 100%, one patient with polymyositis showed decreased GAA activity in dried blood spots that was not confirmed when the enzyme activity was assessed in isolated lymphocytes. Although the DBS test is valid for the screening of Pompe disease in non-newborn patients, enzyme activities in DBS have been shown to be significantly lower in adult individuals{Brand, 2013 #105}, which might explain the low GAA activity observed in the false positive polymyositis patient. Further studies addressed to clarify the sensitivity and specificity of the test in adults are needed, and by the moment, confirmatory analysis of low GAA activity determined by DBS in adults by means of isolated activity in peripheral blood lymphocytes and/or genetic testing is mandatory. Previous studies have shown patients with Pompe, based on DBS test results, among patients with unclassified limb-girdle muscular dystrophies [22], and among patients with hyperCKmeia [23]. The mentioned studied series were short and thus, the current study adds on evidence to previous results regarding unclassified myopathies. One major limitation of the study is its non-prospective design, which might lead to bias. Thus we could not talk about true prevalence of Pompe in patients with undiagnosed myopathies and/or hyperCKemia. However, taken the data obtained, we could still conclude that some of these patients, at least those with myopathies, are undiagnosed Pompe cases. Further prospective studies nation-wide should be performed to establish the prevalence of Pompe among these patients in the Spanish population. 4.1. Conclusions Two out of 62 patients with unclassified myopathies were diagnosed with Pompe disease. Neither one presented histological findings consistent with glycogen storage disease, confirming that relying solely on biopsy data often leads to false-negative results. One patient diagnosed with polymyositis provided an example of a false positive result, showing decreased GAA activity in DBS, which was not confirmed in isolated lymphocytes,
Please cite this article as: J. Pérez-López, et al., Delayed diagnosis of late-onset Pompe disease in patients with myopathies of unknown origin and/ or hyperCKemia, Mol. Genet. Metab. (2015), http://dx.doi.org/10.1016/j.ymgme.2015.02.004
4
J. Pérez-López et al. / Molecular Genetics and Metabolism xxx (2015) xxx–xxx
stressing the importance of diagnosis confirmation after DBS positive results. Diagnosis of late-onset Pompe disease should be considered among patients with myopathy of unknown origin, a group of patients where the diagnosis of this disease is often delayed. Conflict of interest disclosures Jordi Pérez-López and Miguel A Torralba-Cabeza have received honoraria from Genzyme as advisory board members. Acknowledgments Funding sources for the logistical support of this study were provided by Genzyme, a Sanofi company (Sanofi-Aventis, S.A., Spain). Study ClinicalTrials.gov identifier: NCT01482494. Almudena PardoMateos provided editorial support, which was funded by Genzyme Corporation, and a Sanofi company. References [1] R. Hirschhorn, A.J. Reuser, Glycogen storage disease type II: acid alphaglucosidase (acid maltase) deficiency, in: B.A. Scriver, W. Sly, D. Valle (Eds.), The Metabolic and Molecular Bases of Inherited Disease, 8th ed.McGraw-Hill, New York, 2001, pp. 3389–3420. [2] A.T. van der Ploeg, A.J. Reuser, Pompe's disease, Lancet 372 (9646) (Oct 11 2008) 1342–1353. [3] A. Engel, R. Hirschhorn, M.L. Huie, Acid maltase deficiency, in: E. AF-AC (Ed.), Myology, 3rd ed.McGraw-Hill, New York, 2004. [4] P.S. Kishnani, D. Corzo, N.D. Leslie, et al., Early treatment with alglucosidase alpha prolongs long-term survival of infants with Pompe disease, Pediatr. Res. 66 (3) (Sep 2009) 329–335. [5] C.M. van Gelder, C.I. van Capelle, B.J. Ebbink, et al., Facial-muscle weakness, speech disorders and dysphagia are common in patients with classic infantile Pompe disease treated with enzyme therapy, J. Inherit. Metab. Dis. 35 (3) (May 2012) 505–511. [6] J.M. de Vries, N.A. van der Beek, W.C. Hop, et al., Effect of enzyme therapy and prognostic factors in 69 adults with Pompe disease: an open-label single-center study, Orphanet J. Rare Dis. 7 (2012) 73. [7] S. Strothotte, N. Strigl-Pill, B. Grunert, et al., Enzyme replacement therapy with alglucosidase alfa in 44 patients with late-onset glycogen storage disease type 2: 12-month results of an observational clinical trial, J. Neurol. 257 (1) (Jan 2010) 91–97.
[8] B. Bembi, F.E. Pisa, M. Confalonieri, et al., Long-term observational, non-randomized study of enzyme replacement therapy in late-onset glycogenosis type II, J. Inherit. Metab. Dis. 33 (6) (Dec 2010) 727–735. [9] C. Angelini, C. Semplicini, S. Ravaglia, et al., Observational clinical study in juvenileadult glycogenosis type 2 patients undergoing enzyme replacement therapy for up to 4 years, J. Neurol. 259 (5) (May 2012) 952–958. [10] D. Orlikowski, N. Pellegrini, H. Prigent, et al., Recombinant human acid alphaglucosidase (rhGAA) in adult patients with severe respiratory failure due to Pompe disease, Neuromuscul. Disord. 21 (7) (Jul 2011) 477–482. [11] C. Regnery, C. Kornblum, F. Hanisch, et al., 36 months observational clinical study of 38 adult Pompe disease patients under alglucosidase alfa enzyme replacement therapy, J. Inherit. Metab. Dis. 35 (5) (Sep 2012) 837–845. [12] A.T. van der Ploeg, P.R. Clemens, D. Corzo, et al., A randomized study of alglucosidase alfa in late-onset Pompe's disease, N. Engl. J. Med. 362 (15) (Apr 15 2010) 1396–1406. [13] D. Gungor, M.E. Kruijshaar, I. Plug, et al., Impact of enzyme replacement therapy on survival in adults with Pompe disease: results from a prospective international observational study, Orphanet J. Rare Dis. 8 (1) (Mar 27 2013) 49. [14] Z. Lukacs, P. Nieves Cobos, E. Mengel, et al., Diagnostic efficacy of the fluorometric determination of enzyme activity for Pompe disease from dried blood specimens compared with lymphocytes-possibility for newborn screening, J. Inherit. Metab. Dis. 33 (1) (Feb 2010) 43–50. [15] L. Gort, M.J. Coll, A. Chabas, Glycogen storage disease type II in Spanish patients: high frequency of c.1076-1G N C mutation, Mol. Genet. Metab. 92 (1–2) (Sep-Oct 2007) 183–187. [16] P.S. Kishnani, R.D. Steiner, D. Bali, et al., Pompe disease diagnosis and management guideline, Genet. Med. 8 (5) (May 2006) 267–288. [17] M.G. Ausems, P. Lochman, O.P. van Diggelen, et al., A diagnostic protocol for adultonset glycogen storage disease type II, Neurology 52 (4) (Mar 10 1999) 851–853. [18] L.D. Hobson-Webb, A.D. Proia, B.L. Thurberg, et al., Autopsy findings in late-onset Pompe disease: a case report and systematic review of the literature, Mol. Genet. Metab. 106 (4) (Aug 2012) 462–469. [19] A.A. Amato, R.C. Griggs, Unicorns, dragons, polymyositis, and other mythological beasts, Neurology 61 (3) (Aug 12 2003) 288–289. [20] K. Umapathysivam, J.J. Hopwood, P.J. Meikle, Determination of acid alphaglucosidase activity in blood spots as a diagnostic test for Pompe disease, Clin. Chem. 47 (8) (Aug 2001) 1378–1383. [21] Pompe Disease Diagnostic Working G, B. Winchester, D. Bali, et al., Methods for a prompt and reliable laboratory diagnosis of Pompe disease: report from an international consensus meeting, Mol. Genet. Metab. 93 (3) (Mar 2008) 275–281. [22] N. Preisler, Z. Lukacs, L. Vinge, et al., Late-onset Pompe disease is prevalent in unclassified limb-girdle muscular dystrophies, Mol. Genet. Metab. 110 (3) (Nov 2013) 287–289. [23] M. Spada, F. Porta, L. Vercelli, et al., Screening for later-onset Pompe's disease in patients with paucisymptomatic hyperCKemia, Mol. Genet. Metab. 109 (2) (Jun 2013) 171–173.
Please cite this article as: J. Pérez-López, et al., Delayed diagnosis of late-onset Pompe disease in patients with myopathies of unknown origin and/ or hyperCKemia, Mol. Genet. Metab. (2015), http://dx.doi.org/10.1016/j.ymgme.2015.02.004
