An integrative correlation of myopathology, phenotype and genotype in late onset Pompe disease.

AIMS: Pompe disease is caused by pathogenic mutations in the alpha 1,4-glucosidase (GAA) gene and in patients with late onset Pome disease (LOPD), genotype-phenotype correlations are unpredictable. Skeletal muscle pathology includes glycogen accumulation and altered autophagy of various degrees. A correlation of the muscle morphology with clinical features and the genetic background in GAA may contribute to the understanding of the phenotypic variability. METHODS: Muscle biopsies taken before enzyme replacement therapy were analysed from 53 patients with LOPD. On resin sections, glycogen accumulation, fibrosis, autophagic vacuoles and the degree of muscle damage (morphology-score) were analysed and the results were compared with clinical findings. Additional autophagy markers microtubule-associated protein 1A/1B-light chain 3, p62 and Bcl2-associated athanogene 3 were analysed on cryosections from 22 LOPD biopsies. RESULTS: The myopathology showed a high variability with, in most patients, a moderate glycogen accumulation and a low morphology-score. High morphology-scores were associated with increased fibrosis and autophagy highlighting the role of autophagy in severe stages of skeletal muscle damage. The morphology-score did not correlate with the patient's age at biopsy, disease duration, nor with the residual GAA enzyme activity or creatine-kinase levels. In 37 patients with LOPD, genetic analysis identified the most frequent mutation, c.-32-13T>G, in 95%, most commonly in combination with c.525delT (19%). No significant correlation was found between the different GAA genotypes and muscle morphology type. CONCLUSIONS: Muscle morphology in LOPD patients shows a high variability with, in most cases, moderate pathology. Increased pathology is associated with more fibrosis and autophagy.

Expanding the phenotype of DNAJC3 mutations: A case with hypothyroidism additionally to diabetes mellitus and multisystemic neurodegeneration.

Identification of this additional patient from a distant part of the originally described pedigree (Synofzik et al. 2014) confirms pathogenicity of DNAJC3 mutations. Hypothyroidism is a newly identified feature in addition to the known phenotype (diabetes with multisystemic neurodegeneration).

Altered localization, abnormal modification and loss of function of Sigma receptor-1 in amyotrophic lateral sclerosis.

Intracellular accumulations of mutant, misfolded proteins are major pathological hallmarks of amyotrophic lateral sclerosis (ALS) and related disorders. Recently, mutations in Sigma receptor 1 (SigR1) have been found to cause a form of ALS and frontotemporal lobar degeneration (FTLD). Our goal was to pinpoint alterations and modifications of SigR1 in ALS and to determine how these changes contribute to the pathogenesis of ALS. In the present study, we found that levels of the SigR1 protein were reduced in lumbar ALS patient spinal cord. SigR1 was abnormally accumulated in enlarged C-terminals and endoplasmic reticulum (ER) structures of alpha motor neurons. These accumulations co-localized with the 20s proteasome subunit. SigR1 accumulations were also observed in SOD1 transgenic mice, cultured ALS-8 patient's fibroblasts with the P56S-VAPB mutation and in neuronal cell culture models. Along with the accumulation of SigR1 and several other proteins involved in protein quality control, severe disturbances in the unfolded protein response and impairment of protein degradation pathways were detected in the above-mentioned cell culture systems. Furthermore, shRNA knockdown of SigR1 lead to deranged calcium signaling and caused abnormalities in ER and Golgi structures in cultured NSC-34 cells. Finally, pharmacological activation of SigR1 induced the clearance of mutant protein aggregates in these cells. Our results support the notion that SigR1 is abnormally modified and contributes to the pathogenesis of ALS.

Pain in adult patients with Pompe disease: a cross-sectional survey.

BACKGROUND: Pompe disease is a rare hereditary metabolic myopathy caused by a deficiency of acid-α-glucosidase. We investigated the presence and severity of pain and its interference with daily activities in a large group of adults with Pompe disease, who we compared with an age-matched control group. METHODS: Data were collected in a cross-sectional survey in Germany and The Netherlands. Pain was assessed using the short-form brief pain inventory (BPI). Patients also completed the Short Form-36 item (SF-36v2), the Hospital Anxiety and Depression Scale (HADS) and the Rotterdam Handicap Scale (RHS). RESULTS: Forty-five percent of the 124 adult Pompe patients reported having had pain in the previous 24h, against 27% of the 111 controls (p=0.004). The median pain severity score in Pompe patients reporting pain was 3.1 (on a scale from 0 to 10), indicating mild pain; against 2.6 amongst controls (p=0.06). The median score of pain interference with daily activities in patients who reported pain was 3.3, against 1.3 in controls (p=0.001). Relative to patients without pain, those with pain had lower RHS scores (p=0.02), lower SF-36 Physical and Mental component summary scores (p<0.001 and p=0.049), and higher levels of depression and anxiety (p=0.005 and p=0.003). CONCLUSIONS: To date, this is one of the largest studies on pain in a specific neuromuscular disorder. Nearly one in two Pompe patients had experienced pain in the previous 24h. Although pain severity and its interference with daily life were mild, pain was related to a reduced quality of life, less participation in daily life, and greater depression and anxiety. Its management should therefore be seen as part of clinical practice involving Pompe patients.

[Metabolic and mitochondrial myopathies]. / Metabolische und mitochondriale Myopathien.

Metabolic myopathies include a broad group of diseases involving inherited enzyme defects in the various metabolic pathways and skeletal musculature. They show an extensive phenotypic variability of symptoms and different ages of manifestation. Symptoms often included intolerance to duress or permanent paresis. Some forms of metabolic myopathy, in particular mitochondriopathy, are associated with multsystemic organ participation. The diagnostics must be adjusted to individual cases and carried out in stages. Primary investigations should include blood parameters (e.g. creatine kinase measurement, muscle load tests and determination of the acylcarnitine spectrum) and a second step includes muscle biopsy for histological and enzyme investigations and special molecular genetic tests although the causative enzyme defect cannot be clarified in every case. On the other hand by means of a thorough investigation it is particularly important in patients with load intolerance to differentiate between other causes, in particular psychosomatic diseases. If this is not done there is a danger of classifying the symptoms of a metabolic myopathy as a somatoform disorder. Therapy is mostly symptom-oriented as Pompe disease is the only one which can be treated with enzyme replacement therapy.

[Myofibrillary myopathy due to the ZASP mutation Ala147Thr : two cases with exclusively distal leg involvement]. / Myofibrilläre Myopathie bei ZASP-Mutation Ala147Thr : Zwei Fälle mit rein distalem Phänotyp der Beine.

This article describes two patients with late onset myofibrillary myopathy due the ZASP mutation Ala147Thr. The Z-band alternatively spliced PDZ motif containing protein (ZASP) is a sarcomeric protein and interacts with α-actinin at the Z-disk. So far, myopathy due the ZASP mutation Ala147Thr was usually associated with distal and proximal involvement. The two patients with the ZASP mutation Ala147Thr described here showed only distal involvement of the legs without proximal weakness and involvement of the upper limb 6 and 19 years after onset of muscle weakness, respectively.

[Diagnosis and therapy of late onset Pompe disease]. / Diagnose und Therapie des Late-onset-Morbus-Pompe.

As Pompe disease glycogen storage disease type 2 with a severely reduced life expectancy is now a treatable disorder, accurate diagnostic procedures and evidence-based indications for therapy are mandatory. We screened the literature for consensus reports and published trial data of late-onset Pompe disease. These data were summarized in a Delphi consensus method approach. The clinical suspicion of late-onset Pompe disease should be substantiated by the validated dry blood spot test measurement for acid α-glucosidase activity. Alternatively, enzyme activity analysis in lymphocytes is also feasible. Glucosidase α gene sequencing for verifying the diagnosis is recommended. A muscle biopsy including measurements of acid α-glucosidase activity and glycogen concentration is warranted for differential diagnosis in selected cases. The confirmed diagnosis should lead to a multidisciplinary treatment approach, possibly including enzyme replacement therapy.

[Muscular dystrophy due to mutations in anoctamin 5: clinical and molecular genetic findings]. / Muskeldystrophie infolge Anoctamin-5-Mutationen : Klinische und molekulargenetische Befunde.

Recessive mutations in the anoctamin 5 (ANO5) gene have been recently identified in families with limb girdle muscular dystrophy (LGMD2L) and distal non-dysferlin Miyoshi myopathy. Anoctamin 5 is supposed to be a putative calcium-activated chloride channel. We report five German patients (four index patients) with muscle dystrophy due to mutations in the ANO5 gene. Sequencing of the ANO5 exons 5, 13 and 20 was performed to screen for a common c.191dupA mutation and two other reported mutations (c.1295C>G and p.R758C). The whole coding region of the ANO5 gene was sequenced to identify new mutations. Phenotypically, three patients showed LGMD and one patient Miyoshi type distal myopathy. One sibling had asymptomatic hyperCKemia. The age at onset was 64, 38 and 40 years in patients with LGMD and 23 years in the patient with distal myopathy. The four symptomatic patients showed remarkable asymmetric muscle involvement. There was marked CK elevation (11 to 30 times). Electron microscopy showed multifocal gaps in the sarcolemmal membrane. All patients harboured the common c.191dupA mutation in at least one allele. Two patients with LGMD were homozygous and the third patient and his asymptomatic sister were compound heterozygous for the c.191dupA mutation and a novel p.T548I mutation. The patient with distal myopathy harboured the p.R758C mutation in the second allele. Mutations in the ANO5 gene seem to be a relatively common cause of muscular dystrophy in Germany. Cases with late onset or asymptomatic hyperCKemia can occur. Clinically, asymmetric manifestation is typical.

Magnetic Resonance Imaging Characteristics of Retinal Vasculopathy with Cerebral Leukoencephalopathy and Systemic Manifestations.

BACKGROUND: Retinal vasculopathy with cerebral leukoencephalopathy and systemic manifestations (RVCL-S) is a rare hereditary disease presenting with distinct imaging features in middle-aged adults. This article describes the typical imaging features focusing on the longitudinal course of RVCL-S lesions. METHODS: In this study six subjects (five male, five related) with RVCL-S were retrospectively included from two university hospitals. The median age of symptom onset was 40 ± 6 years. Magnetic resonance imaging (MRI) covering baseline and a median follow-up period of 33 months was reviewed in a structured way focusing on morphology, contrast enhancement and diffusion restriction of brain lesions. RESULTS: All patients showed patchy, T2 hyperintense white matter lesions (mean number 7.7 ± 1.8) with a periventricular predominance at the frontal lobes (59%). In all subjects, rim-enhancing white matter lesions with temporary diffusion restriction were present for a mean of 5.0 ± 3.9 months. Median duration of blood brain barrier disruption was 20 months. CONCLUSION: Periventricular patchy white matter lesions in the frontal lobes as well as rim-enhancing lesions with prolonged diffusion restriction and long-lasting contrast enhancement are characteristic imaging findings in RCVL-S and can be helpful in the differential diagnosis.

[Chronic progressive external ophthalmoplegia--symptom or syndrome?]. / Chronisch progressive externe Ophthalmoplegie--Symptom oder Syndrom?

The term chronic progressive external ophthalmoplegia (CPEO) is not only a symptom but is also used as a syndrome within the group of mitochondrial diseases. However, the symptom CPEO might also occur in other well defined mitochondrial syndromes such as MELAS, MNGIE, SANDO. The molecular bases of the syndrome CPEO are mostly single or multiple deletions of the mtDNA, less frequently point mutations. Multiple deletions are caused by defects of nuclear encoded proteins. In this case, the mode of inheritance might be autosomal dominant or recessive. However, all these types of mtDNA mutations are not only associated with the symptom or syndrome of CPEO but might also cause other well defined mitochondrial syndromes. Thus, the diagnosis of CPEO either as a symptom or as a syndrome requires the subtle characterisation of the complete clinical phenotype as well as the precise genotype. Only on this basis a valid prognosis and information about the mode of inheritance are possible.

Methods for a prompt and reliable laboratory diagnosis of Pompe disease: report from an international consensus meeting.

Pompe disease is an autosomal recessive disorder of glycogen metabolism caused by a deficiency of the lysosomal enzyme acid alpha-glucosidase (GAA). It presents at any age, with variable rates of progression ranging from a rapidly progressive course, often fatal by one-year of age, to a more slowly, but nevertheless relentlessly progressive course, resulting in significant morbidity and premature mortality. In infants, early initiation of enzyme replacement therapy is needed to gain the maximum therapeutic benefit, underscoring the need for early diagnosis. Several new methods for measuring GAA activity have been developed. The Pompe Disease Diagnostic Working Group met to review data generated using the new methods, and to establish a consensus regarding the application of the methods for the laboratory diagnosis of Pompe disease. Skin fibroblasts and muscle biopsy have traditionally been the samples of choice for measuring GAA activity. However, new methods using blood samples are rapidly becoming adopted because of their speed and convenience. Measuring GAA activity in blood samples should be performed under acidic conditions (pH 3.8-4.0), using up to 2 mM of the synthetic substrate 4-methylumbelliferyl-alpha-D-glucoside or glycogen (50 mg/mL), in the presence of acarbose (3-9 microM) to inhibit the isoenzyme maltase-glucoamylase. The activity of a reference enzyme should also be measured to confirm the quality of the sample. A second test should be done to support the diagnosis of Pompe disease until a program for external quality assurance and proficiency testing of the enzymatic diagnosis in blood is established.

Molecular diagnosis of German patients with late-onset glycogen storage disease type II.

UNLABELLED: In patients with late-onset glycogen storage disease type II, one mutation, c.-32-13T>G, in the α-glucosidase (GAA) gene is identified frequently in European populations from different regions along with many rarer mutations. We have performed molecular genetic investigations in 18 German index patients with late-onset disease. The c.-32-13T>G, c.525delT (p.Glu176fsX45), and c.2481+102_2646+31del mutations were detected by PCR/restriction enzyme digest. Other mutations were detected by sequencing. All patients were compound heterozygous and 17 patients harboured the c.-32-13T>G mutation. Seven other previously described mutations (including the c.-32-13T>G) were identified, of which the p.C103G (c.307T>G) and the c.2481+102_2646+31del mutations were present each in three unrelated patients. Sequencing revealed five novel mutations. CONCLUSIONS: Genetic testing was able to identify the genetic defects in all patients and screening of the c.-32-13T>G mutation identified 94% of the cases. This is important for quick and reliable diagnosis, especially in view of enzyme replacement. Among the rarer mutations, c.2481+102_2646+31del and p.C103G are rather frequent in Germany.

Analysis of spectrum and frequencies of mutations in McArdle disease. Identification of 13 novel mutations.

BACKGROUND: McArdle disease, a common metabolic myopathy with autosomal recessive inheritance, is caused by a frequent R50X mutation and many rare mutations in the myophosphorylase gene. OBJECTIVES: To identify spectrum and frequencies of myophosphorylase gene mutations in a large cohort of patients with McArdle disease, to discuss diagnostic implications, and to analyse genotype-phenotype relationship. METHODS: Molecular genetic analysis of 56 index patients with muscle biopsy-proven myophosphorylase deficiency from Germany (n = 35), UK (n = 13), and several other countries (n = 8) was performed using direct sequencing. RESULTS: Allele frequency of the R50X mutation was 58%, and 71% of the patients carried this mutation at least on one allele. We detected 26 other less common mutations, 13 of which are novel: G157V, R161C, Q337R, E384K, S450L, G486D, R570W, K575E, IVS6-2A>T, IVS10+1G>A, R650X, c.1354insC, c.1155_1156delGG. There was no genotype-phenotype correlation with respect to age of onset and severity. R270X was the most frequent mutation among the less common mutations reaching an allele frequency of 5% followed by R94W and G686R representing a frequency of 4% each. CONCLUSIONS: The study further extends the genetic heterogeneity of myophosphorylase gene mutations showing no mutational hotspot and no genotype-phenotype correlation. Most novel missense mutations were located in secondary structures or active sites of the enzyme. Some of the less common mutations are recurrent with different frequencies within Europe. Ethnic origin and frequency of less common mutations must be considered to establish efficient strategies in molecular genetic testing. Performing molecular testing can avoid muscle biopsy.

Frequency of calpain-3 c.550delA mutation in limb girdle muscular dystrophy type 2 and isolated hyperCKemia in German patients.

OBJECTIVE: Calpain-3 deficiency is the most common cause of autosomal-recessive limb girdle muscular dystrophy (LGMD2). The c.550delA mutation in the CAPN3 gene was frequently identified in LGMD2A patients from Eastern Europe and is considered a Slavic founder mutation. METHODS: We screened for the c.550delA mutation in unrelated German patients with LGMD2 (n = 98) and in patients with asymptomatic or minimally symptomatic (myalgia or fatigue) hyperCKemia of unknown origin (n = 102). Results of Western blot analysis were available in 75 patients with LGMD2 and 65 patients with hyperCKemia. In samples that were heterozygous for the c.550delA mutation, the whole CAPN3 gene was analyzed by sequencing in order to detect the second mutation. RESULTS: The c.550delA mutation was found in 8.1% of LGMD2 (n = 1 homozygous, n = 7 heterozygous) and 1.9% of hyperCKemia patients (n = 2 heterozygous). In 8 of the 9 hetrozygous patients, a second CAPN3 mutation was identified by direct sequencing. Two mutations (Val509Phe and Gln565Stop) have not been reported before. Absent or deficient calpain-3 protein in Western blot analysis was found in 22.5% of the LGMD2 patients and 11% of the patients with hyperCKemia. Western blot results were available in 9 out of the 10 patients with genetically confirmed LGMD2A and were clearly abnormal in 6 patients, suspicious in 2 and entirely normal in 1. Two LGMD2 patients with the c.550delA mutation and onset within the first 2 decades had joint contractures. Muscle biopsy revealed inflammatory changes in three patients. CONCLUSION: The CAPN3 gene mutation c.550delA is rather frequently observed in German patients with LGMD2, but also occasionally in cases with isolated hyperCKemia.

Genetic heterogeneity in 30 German patients with oculopharyngeal muscular dystrophy.

Oculopharyngeal muscular dystrophy (OPMD) is due to short elongations of a polyalanine tract in the poly(A) binding protein nuclear 1 (PABPN1) gene. Originally GCG expansions in which (GCG)(6) is extended to (GCG)(7-13) were found. Subsequently five further genotypes with additional GCA- and GCG-trinucleotides were identified in single OPMD patients. This indicated larger genetic heterogeneity and showed that unequal crossing-over and not replication slippage must be the underlying mechanism of elongation.We performed sequencing of the PABPN1 gene in 30 German OPDM index patients to determine the exact genotype. The original GCG expansion ranging from (GCG)(8) to (GCG)(11) was found in 22 patients. In 8 patients, however, three different elongated alleles other than classical (GCG)(7-13) were observed. Two of these genotypes had already been identified in Japanese patients. One genotype was recently identified showing (GCG)(6) followed by inserted (GCA)(3)GCG in four unrelated patients. This study further supports the theory of unequal crossing over as the molecular mechanism leading to elongation. It shows that other genotypes than classical (GCG)(7-13) are rather common in German OPMD patients. The data imply that there is no single founder effect in German OPMD patients.

Cardiac involvement in limb-girdle muscular dystrophy 2I : conventional cardiac diagnostic and cardiovascular magnetic resonance.

BACKGROUND: The C826A mutation in the fukutin-related protein (FKRP) gene is typically associated with autosomal recessive limb-girdle muscular dystrophy 2I (LGMD2I) but oligosymptomatic phenotypes and patients with predominant cardiac involvement are also described. OBJECTIVE: To assess cardiac involvement in patients with LGMD2I. PATIENTS: Nine patients from 5 families (2 female, 7 male) homozygous for the 826C > A FKRP mutation were included. METHODS: Additional to conventional cardiac investigations (electrocardiography and echocardiography) the patients underwent cardiovascular magnetic resonance imaging (CMR). RESULTS/CONCLUSION: Cardiac involvement was detected by CMR in eight of nine patients (reduced left ventricular ejection fraction in 6, enlargement of left ventricular end-diastolic volume in 2 and left ventricular mass in 2) and in four patients by conventional cardiac diagnostic investigations. Two of the nine patients showed no muscle weakness or atrophy but suffered myalgias; both had cardiac manifestation of the disease. CMR is a sensitive method for detecting cardiac abnormalities in patients with LGMD2I and can be used for early detection of mild or subclinical cardiac involvement.

LGMD 2I due to the common mutation 826C>A in the FKRP gene presenting as myopathy with vacuoles and paired-helical filaments.

We report on two unrelated patients clinically presenting with late-onset progressive limb girdle weakness; cardiomyopathy was seen in one patient. Muscle biopsy revealed a necrotic myopathy with numerous rimmed vacuoles, ultrastructurally typical paired-helical filaments, and reduced immunohistochemical staining for alpha-dystroglycan. Quadriceps sparing hereditary inclusion body myopathy due to mutations in GNE gene, and OPMD due to PABPN1 mutations were excluded, genetically. We detected a homozygous mutation of the FKRP gene (826C>A) in both patients. Mutations of FKRP have been reported in congenital muscular dystrophies, LGMD2I, cardiomyopathy and hyperCKemia, but not in myopathies with vacuoles and paired-helical filaments. Therefore, our findings further extend the morphological variability of muscular dystrophies due to FKRP mutations.

Dilated cardiomyopathy may be an early sign of the C826A Fukutin-related protein mutation.

Limb-girdle muscular dystrophy LGMD2I is caused by mutations in the fukutin-related protein (FKRP) gene. Clinically, LGMD2I exhibits a great phenotypic variability ranging from severe, rapidly progressive weakness and wasting of the limb-girdle muscles to mild disorders. Here, we present three siblings without clinical signs of muscle dystrophy, but with dilated cardiomyopathy. Elevated serum creatine kinase level and partial fatty degeneration of muscles on MRI indicated subclinical involvement of skeletal muscles. The patients were homozygous for the common C826A mutation in the FKRP gene. Although cardiac involvement in patients with clinically typical LGMD2I was previously described, no patient with dilated cardiomyopathy as the only clinical manifestation of the FKRP mutation was reported so far.

Morphology and function of cerebral arteries in adults with pompe disease.

OBJECTIVE: Cerebrovascular abnormalities have been reported in adult patients with Pompe disease. The objective was to study these abnormalities by (1) determining the diameter and mean flow velocity (MFV) of large cerebral arteries and (2) estimating cerebral blood flow (CBF), resistance index (RI) and cerebrovascular reactivity (CVR) as functions of resistance vessels. METHODS: In ten adults with Pompe disease and twenty controls, the diameter, peak systolic (PSV) and end-diastolic velocities (EDV) of arteries supplying the brain were quantified by MR angiography and sonography. MFV, RI and CBF were calculated. CVR in the middle cerebral artery (MCA) was determined by hyperventilation and acetazolamide injection. RESULTS: MR angiography revealed dilation of cerebral arteries predominantly in the posterior circulation. Dilative arteriopathy was found in three patients; two of them showed vertebrobasilar dolichoectasia. Despite of the dilative arteriopathy, the MFV was normal, indicating increased CBF and dilated resistance vessels. RI of all examined arteries and CVR of MCA were normal. CONCLUSION: The data suggest that dilation of small and large cerebral arteries is a common feature in adults with Pompe disease. Increased CBF might be the consequence of dilated resistance vessels. However, dysfunction of resistance vessels was rarely found. SYNOPSIS: In adults with Pompe disease, dilation of small and large cerebral arteries is a common feature and might be associated with increased cerebral blood flow.