Available online at www.sciencedirect.com ScienceDirect Neuromuscular Disorders 24 (2014) 272–276 www.elsevier.com/locate/nmd Case report Adult polyglucosan body disease in a patient originally diagnosed with Fabry’s disease A. Sagnelli a, M. Savoiardo b, C. Marchesi a, L. Morandi c, M. Mora c, M. Morbin d, L. Farina b, A. Mazzeo e, A. Toscano e, S. Pagliarani f, S. Lucchiari f, G.P. Comi f, E. Salsano a, D. Pareyson a,⇑ a Clinic of Central and Peripheral Degenerative Neuropathies Unit, Department of Clinical Neurosciences, IRCCS Foundation, “C. Besta” Neurological Institute, Milan, Italy b Unit of Neuroradiology, Department of Diagnostic and Applied Technology, IRCCS Foundation, “C. Besta” Neurological Institute, Milan, Italy c Neuromuscular Diseases and Neuroimmunology Unit, Department of Clinical Neurosciences, IRCCS Foundation, “C. Besta” Neurological Institute, Milan, Italy d Division of Neurology V and Neuropathology, Department of Diagnostic and Applied Technology, IRCCS Foundation, “C. Besta” Neurological Institute, Milan, Italy e Department of Neurosciences, University of Messina, Messina, Italy f Dino Ferrari Center, Department of Pathophysiology and Transplantation (DEPT), University of Milan, Neurology Unit, IRCCS Foundation Ca’ Granda, Ospedale Maggiore Policlinico, Milan, Italy Received 12 September 2013; accepted 12 November 2013 Abstract Adult polyglucosan body disease is a rare autosomal recessive disease, caused by glycogen branching enzyme gene mutations, characterised by urinary dysfunction, spastic paraplegia with vibration sense loss, peripheral neuropathy, and cognitive impairment. Fabry’s disease is an X-linked lysosomal storage disorder caused by a-galactosidase A gene mutations; neurological manifestations include cerebrovascular accidents, small-fibre neuropathy and autonomic dysfunction. Here, we report the case of a 44-year-old Sicilian male with stroke-like episodes, hypohidrosis and mild proteinuria, which led to the diagnosis of Fabry’s disease after a hemizygous mutation (p.Ala143Thr) in a-galactosidase A gene was detected. Subsequently, he developed progressive walking difficulties and dementia, which were considered atypical for Fabry’s disease. Therefore, we performed additional investigations that eventually led to the diagnosis of adult polyglucosan body disease caused by two novel missense mutations (p.Asp413His and p.Gly534Val) in the glycogen branching enzyme gene. Recently, the pathogenic role of the p.Ala143Thr mutation in causing Fabry’s disease has been questioned. This case underlines the importance of performing further investigations when facing with atypical features even in the presence of a genetic diagnosis of a rare disease. Ó 2013 Elsevier B.V. All rights reserved. Keywords: Adult polyglucosan body disease; Fabry’s disease; 1,4-Alpha-glucan branching enzyme; a-Galactosidase A; Lysosomal storage disease 1. Introduction ⇑ Corresponding author. Address: Clinic of Central and Peripheral Degenerative Neuropathies Unit, Department of Clinical Neurosciences, IRCCS Foundation, “C. Besta” Neurological Institute, via Celoria 11, 20133 Milan, Italy. Tel.: +39 02 2394 3001; fax: +39 02 2394 2293. E-mail address: davide.pareyson@istituto-besta.it (D. Pareyson). 0960-8966/$ - see front matter Ó 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.nmd.2013.11.006 Adult polyglucosan body disease (APBD) is a very rare neurological disorder that typically occurs in individuals over age 40 years, characterised by neurogenic bladder, spastic paraplegia with vibration sense loss, predominantly axonal, sensory-motor polyneuropathy, and cognitive impairment [1]. The disease is due to deficiency of A. Sagnelli et al. / Neuromuscular Disorders 24 (2014) 272–276 glycogen branching enzyme (GBE1) which leads to intracellular accumulation of polyglucosan bodies (PBs), containing amylopectin-like polysaccharide, in the central and peripheral nervous systems and in other tissues such as muscle and skin [2]. APBD is allelic to glycogen storage disease type IV (GSD IV), a childhood disorder more frequently presenting with liver disease, progressing to lethal cirrhosis, and variable neuromyopathic involvement [3–5]. The majority of APBD patients are of Ashkenazi Jewish origin and have a homozygous (p.Tyr329Ser) mutation in GBE1, that is the only gene associated with APBD; other APBD-associated mutations of this gene, occurring also in non-Jewish persons, are on the record [1,6,7]. Diagnosis of APBD is based on: clinical findings; magnetic resonance imaging (MRI) showing bilateral periventricular and subcortical white matter changes with diffuse atrophy of the brain, medulla and spinal cord [1,8]; sural nerve biopsy (characteristic accumulation of PBs). It is confirmed by reduced enzymatic GBE1 activity in skin fibroblasts or muscle tissue, and molecular genetic testing of GBE1. Fabry’s disease (FD) is an X-linked lysosomal storage disorder, caused by mutations in the a-galactosidase A gene (GLA), resulting in deficiency of a-galactosidase A enzyme (a-Gal A) that leads to accumulation of glycosphingolipids (mainly globotriaosylceramide, Gb3) in many tissues and cell types with subsequent organ failure [9]. The most common presenting features in affected males, appearing during childhood, are burning pain in the extremities, gastrointestinal symptoms, hypohidrosis (related either to a direct effect on sweat glands and to autonomic neuropathy) and angiokeratomas (characteristic reddish-purple skin lesions); learning and growth delay are less frequent findings. In the second decade of life, progressive renal failure and cardiac disease usually occur. Corneal opacities are found in many patients, without vision impairment. Neurological manifestations include cerebrovascular accidents and a painful small-fibre neuropathy with dysautonomic features [10]. We report a patient originally diagnosed with Fabry’s disease who, after further investigations were performed because of atypical features, was eventually shown to have APBD. Genetic studies showed a missense mutation in the GLA gene, p.Ala143Thr, which pathogenic role has been recently questioned, and two novel mutations (p.Asp413His and p.Gly534Val) in GBE1. 2. Case report A 44-year-old Sicilian male was admitted to our department with a history of gait difficulties, cognitive decline, urinary incontinence and hypohidrosis. His parents were consanguineous (paternal great-grandfather and maternal great-grandmother were first cousins); two of his brothers died during infancy for unspecified liver disease. He started to walk at 2 years and during 273 childhood and youth had a clumsy gait, especially with the right leg. Between age 27 and 38, he had three episodes of sudden lower limb weakness, in one case associated with speech impairment; symptoms partially resolved spontaneously in a few weeks, but always with a residual impairment of gait. By the age of 38 years, he had sensory impairment in lower limbs and progressive worsening of motor symptoms with gait possible only with support. From the same period he showed slowly progressive cognitive decline, characterised by memory deficits and difficulty in planning. At 40 years of age he received elsewhere a diagnosis of Fabry’s disease, on the basis of alpha-galactosidase A deficiency (4 nmol/h/mg in leukocytes, n.v. 14–38) and on the finding of hemizygous GLA p.Ala143Thr (c.427G>A) mutation in exon 3. By the age of 42 years he had also developed hypohidrosis and urinary incontinence. He then started enzymatic replacement therapy with a-Gal A, but symptoms continued to worsen. On admission, neurological examination revealed ataxic and spastic gait, possible with unilateral support, bilateral gaze-evoked nystagmus, dysarthria and positive palmomental reflex. Strength examination showed mild lower limb weakness, more on the right side. Deep tendon reflexes were increased in all limbs, with moderate spasticity in lower limbs; Babinski sign was present bilaterally. Sensory function was altered in lower limbs with a decrease of vibration and position sense and preservation of light touch and pinprick sensation. Cerebellar examination showed a mild loss of coordination of lower limbs. Neuropsychological testing detected mild cognitive decline with difficulty in understanding, planning and learning, memory deficits and constructive apraxia. Routine blood tests were normal except for slight increase in alanine amino transferase (60 U/L, n.v. 0–41) and c-glutamyltransferase (81 U/L, n.v. 8–61), and mild proteinuria (193.50 mg/24 h, n.v. 0–150). Alpha-galactosidase A activity, just before a new replacement infusion, was decreased in leukocytes (16.7 nmol/h/mg, n.v. 30–107; substrate: 4-Methylumbelliferyl-Alfa-D-galactopyranoside; normal reference enzyme: beta-hexosaminidase). Cardiac function, as assessed by EKG and echocardiography, and carotid Doppler ultrasound examination were normal; dermatological evaluation excluded the presence of angiokeratomas and ophthalmological assessment showed the presence of corneal opacity in the right eye. Sympathetic Skin Response (SSR) test showed abnormalities of autonomic system. Nerve conduction studies revealed an axonal motor neuropathy in lower limbs and electromyography showed chronic neurogenic signs in upper and lower limb muscles and sporadic fasciculations in gastrocnemius muscle. Motor evoked potentials (MEPs) revealed slight increase in central conduction time from lower limbs, and somatosensory evoked potentials (SEPs) showed severe 274 A. Sagnelli et al. / Neuromuscular Disorders 24 (2014) 272–276 Fig. 1. Brain MRI. Severe anterior leukoencephalopathy associated with cerebellar, bulbar and cervical spinal cord atrophy. (A) Sagittal T1-weighted image shows atrophy of the anterior corpus callosum, cerebellum, medulla oblongata and spinal cord. (B) Axial T2-weighted and (C) coronal FLAIR images show diffuse white matter abnormalities with cystic degeneration (arrow) prevalent in the frontal regions. Fig. 2. Muscle biopsy. (A and B) Consecutive PAS and H–E stained sections showing accumulation of PAS positive material mostly located under the sarcolemma. (C and D) Electron micrographs showing collections of polyglucosan bodies (C) with electrondense core and lighter peripheral halo; (D) larger magnification. (Scale bars: A, B = 20 lm; C = 2.5 lm; D = 1 lm.) central conduction slowing, greater in lower limbs. Brain and spinal cord MRI showed diffuse hyperintense infra- and supratentorial white matter abnormalities with cystic degeneration prevalent in the frontal regions on T2-w.i. and FLAIR sequences associated with cerebellar, bulbar and cervical spinal cord atrophy (Fig. 1). Needle muscle biopsy of the left quadriceps femoralis revealed neuromyogenic signs with accumulation of PAS-positive PBs (Fig. 2). We could revise a previously performed sural nerve biopsy which showed a mild reduction of the density of small and large myelinated fibres. There were scattered degenerating axons, whereas other myelinated fibres showed evidence of atrophy, secondary remyelination, and regeneration clusters. Several intra- and extra-axonal PBs (many more than what can be seen in the context of normal ageing), 5–80 lm in diameter, were present, associated with axonal distension. Pathological findings were consistent with APBD (Fig. 3). We found no evidence of accumulation of glycosphingolipids in nerve, muscle or skin biopsy. Genomic DNA analysis revealed the presence of two novel missense GBE1 mutations in compound heterozygosity: c.1237G>C in exon 10 (p.Asp413His) and c.1601G>T in exon 12 (p.Gly534Val). Cloning demonstrated that the mutations were located on different alleles. Brancher enzyme activity, measured in A. Sagnelli et al. / Neuromuscular Disorders 24 (2014) 272–276 275 Fig. 3. Sural nerve biopsy. (A) Light microscopic study shows a slight decrease in both small- and large-diameter myelinated fibres associated with scattered wallerian-like degeneration, atrophy, secondary remyelination, and regeneration clusters (A). Intra-axonal and extra-axonal inclusions ranging from 5 to 80 lm in diameter with as many as three inclusions in a single fascicular cross section were present, thus satisfying histological criteria for APBD (A, and magnifications in B and C). (D–G) Electron microscopy study shows myelinated (D) and unmyelinated (E) nerve fibres with intra-axonal round polyglucosan-like inclusions and one inclusion free in the endoneurium (F). The inclusions are not surrounded by membrane and often dislocate the axoplasm to the periphery of axons (E) and consist mainly of branched filaments that are 6–8 nm wide (G). (Scale bars: A = 100 lm; B, C = 20 lm; D, E = 1.5 lm; F = 1 lm; G = 100 nm). two frozen muscle samples (as we could also reexamine a previously performed muscle biopsy), was substantially absent (0–0.2 mmol/min/mg; control muscle value: 319.4 ± 126.4 nmol/min/mg; phosphofructokinase, control enzyme, value: 0.89 nmol/min/mg protein, n.v. 0.91 ± 0.2) [11]. 3. Discussion We report a patient, originally diagnosed with Fabry’s disease, who was eventually found to be affected by APBD, that represents about 3% of all glycogen storage diseases, which overall prevalence is 1:10,000. We believe this case worth reporting because it stimulates some interesting insights. First, we emphasise that further investigations are warranted if the clinical picture is not completely explained by a single disorder, even when this is rare and genetically confirmed [12,13]. Although our patient carried the p.Ala143Thr GLA mutation associated with FD, his symptoms were only partially explainable by this disease. MRI findings were not in keeping with this diagnosis, and no accumulation of glycosphingolipids typical of FD was observed in nerve, muscle and skin biopsies. Actually, the GLA p.Ala143Thr mutation has been reported to result in an attenuated FD phenotype, and in a recent study the pathogenic role of this mutation has even been questioned [14]. Therefore, we concluded that the diagnosis of Fabry’s disease should be revised, that the GLA p.Ala143Thr mutation could not account for his clinical picture and therefore we looked for an additional, co-occurring disease and, with further investigations, including muscle biopsy showing PBs, we confirmed our hypothesis and reached the diagnosis of APBD. Mild proteinuria, hypohidrosis and corneal opacity might still be features of FD [9,10], whereas progressive gait impairment, cognitive decline and urinary incontinence are features of APBD. The previous episodes of sudden neurological deficit remain equivocal, but symptoms fluctuations or subacute worsening are described in APBD. White matter changes are detected in both diseases; however, widespread leukoencephalopathy with frontal and posterior fossa structures’ involvement, thin corpus callosum, and bulbar, spinal and cerebellar atrophy (as in our case) are features pointing to APBD [1]. Secondly, it is noteworthy that our patient was non-Jewish and that despite his parents were 276 A. Sagnelli et al. / Neuromuscular Disorders 24 (2014) 272–276 consanguineous, APBD was due to compound heterozygosity for two different GBE1 mutations. In fact, APBD is an exceedingly rare disease (less than 100 cases described) which usually occurs in people of Ashkenazi Jewish ancestry, and only a few cases have been described in populations of different ethnic origin [1]. The p.Tyr329Ser mutation (in homozygosity or heterozygosity) is by far the most frequent APBD-related GBE1 mutation, while a few other mutations have been reported in non-Ashkenazi-Jewish patients. Here, we found two novel sequence variations, i.e., p.Asp413His in exon 10 and p.Gly534Val in exon 12. Both aspartic acid 413 and glycine 534 are well conserved amongst species and bioinformatic analysis based on the PolyPhen-2 algorithm predicted that each variant is “probably damaging”. Finally, it is tempting to speculate that the fatal liver disease of infancy in the two brothers might be due to glycogen storage disease type IV (allelic to ABPD) caused by the same GBE1 mutations, as genotype and residual enzymatic activity show very loose correlation with phenotype [7]. Acknowledgments We are most grateful to Prof. Stirling Carpenter for his helpful revision of the electron microscopy data of nerve biopsy. We thank Ms. Anna Venerando for the help in obtaining data for the manuscript. References [1] Mochel F, Schiffmann R, Steenweg ME, et al. Adult polyglucosan body disease: natural history and key magnetic resonance imaging findings. Ann Neurol 2012;72:433–41. [2] Milde P, Guccion JG, Kelly J, Locatelli E, Jones RV. Adult polyglucosan body disease: diagnosis by sural nerve and skin biopsy. Arch Pathol Lab Med 2001;125:519–22. [3] Bruno C, Servidei S, Shanske S, et al. Glycogen branching enzyme deficiency in adult polyglucosan body disease. Ann Neurol 1993;33:88–93. [4] Cafferty MS, Lovelace RE, Hays AP, Servidei S, Dimauro S, Rowland LP. Polyglucosan body disease. Muscle Nerve 1991;14:102–7. [5] Bruno C, van Diggelen OP, Cassandrini D, et al. Clinical and genetic heterogeneity of branching enzyme deficiency (glycogenosis type IV). Neurology 2004;63:1053–8. [6] Lossos A, Meiner Z, Barash V, et al. Adult polyglucosan body disease in Ashkenazi Jewish patients carrying the Tyr329Ser mutation in the glycogen-branching enzyme gene. Ann Neurol 1998;44:867–72. [7] Ziemssen F, Sindern E, Schroder JM, et al. Novel missense mutations in the glycogen-branching enzyme gene in adult polyglucosan body disease. Ann Neurol 2000;47:536–40. [8] Berkhoff M, Weis J, Schroth G, Sturzenegger M. Extensive whitematter changes in case of adult polyglucosan body disease. Neuroradiology 2001;43:234–6. [9] Zarate YA, Hopkin RJ. Fabry’s disease. Lancet 2008;372:1427–35. [10] Bersano A, Lanfranconi S, Valcarenghi C, Bresolin N, Micieli G, Baron P. Neurological features of Fabry disease: clinical, pathophysiological aspects and therapy. Acta Neurol Scand 2012;126:77–97. [11] Lossos A, Barash V, Soffer D, et al. Hereditary branching enzyme dysfunction in adult polyglucosan body disease: a possible metabolic cause in two patients. Ann Neurol 1991;30:655–62. [12] Ali Pervaiz M, Patterson MC, Struys EA, et al. Co-morbidity of Sanfilippo syndrome type C and D-2-hydroxyglutaric aciduria. J Neurol 2011;258:1564–5. [13] Thibert R, Hyland K, Chiles J, Steinberg S, Eichler F. Levodopa response reveals sepiapterin reductase deficiency in a female heterozygote with adrenoleukodystrophy. JIMD Rep 2012;3:79–82. [14] Terryn W, Vanholder R, Hemelsoet D, et al. Questioning the pathogenic role of the GLA p.Ala143Thr “mutation” in Fabry disease: implications for screening studies and ERT. J Inherit Metab Dis Rep 2013;8:101–8.