SOD1 p.D12Y variant is associated with amyotrophic lateral sclerosis/distal myopathy spectrum.

BACKGROUND AND PURPOSE: The aim of our study was to describe patients with the p.D12Y variant (previously reported as D11Y) in SOD1 showing heterogeneous clinicopathological features. METHODS: We performed clinical, electrophysiological, magnetic resonance imaging (MRI) and muscle pathology studies in four SOD1 p.D12Y variant-positive patients. RESULTS: The SOD1 p.D12Y clinical manifestations ranged from a benign phenotype characterized by distal distribution of muscular weakness and long survival to classic forms of amyotrophic lateral sclerosis with poor prognosis. Two patients with the distal clinical phenotype showed MRI and muscle pathology alterations indicating a concurrent muscle involvement. In one of these patients significant myopathic changes were associated with rimmed vacuolar pathology. CONCLUSIONS: We expand the clinical spectrum of SOD1 p.D12Y variant, including predominant lower motor neuron forms with long survival and classic forms with aggressive course. Some patients may have concomitant distal myopathy without other explanations. Given clinical, MRI and muscle pathology alterations, SOD1 should be considered in the differential diagnosis of molecularly undefined distal myopathies with rimmed vacuoles.

Diagnostic anoctamin-5 protein defect in patients with ANO5-mutated muscular dystrophy.

AIMS: Previously, detection of ANO5 protein has been complicated by unspecific antibodies, most of which have not identified the correct protein. The aims of the study were to specify ANO5 protein expression in human skeletal muscle, and to investigate if the ANO5 protein levels are affected by different ANO5 mutations in anoctaminopathy patients. METHODS: Four different antibodies were tested for ANO5 specificity. A sample preparation method compatible with membrane proteins, combined with tissue fractionation was used to determine ANO5 expression in cell cultures expressing ANO5, in normal muscles and eight patient biopsies with six different ANO5 mutations in homozygous or compound heterozygous states, and in other dystrophies. RESULTS: Only one specific monoclonal N-terminal ANO5 antibody was efficient in detecting the protein, showing that ANO5 is expressed as a single 107 kD polypeptide in human skeletal muscle. The truncating mutations c.191dupA and c.1261C>T were found to abolish ANO5 expression, whereas the studied point mutations had variable effects; however, all the ANO5 mutations resulted in clearly reduced ANO5 expression in the patient muscle membrane fraction. Attempts to detect ANO5 using immunohistochemistry were not yet successful. CONCLUSIONS: The data presented here indicate that the ANO5 protein expression is decreased in ANO5-mutated muscular dystrophy and that most of the non-truncating pathogenic ANO5 mutations likely destabilize the protein and cause its degradation. The method described here allows direct analysis of human ANO5 protein, which can be used in diagnostics, for evaluating the pathogenicity of the potentially harmful ANO5 variants of uncertain significance.

Novel mutations in DNAJB6 cause LGMD1D and distal myopathy in French families.

BACKGROUND AND PURPOSE: The aim was to determine the genetic background of unknown muscular dystrophy in five French families. METHODS: Twelve patients with limb girdle muscular dystrophy or distal myopathy were clinically evaluated. Gene mutations were identified using targeted exon sequencing and mutated DNAJB6 was tested in vitro. RESULTS: Five patients presented with distal lower limb weakness whilst others had proximal presentation with a variable rate of progression starting at the mean age of 38.5 years. Two novel mutations (c.284A>T, p.Asn95Ile, two families; and c.293_295delATG, p.Asp98del, one family) as well as the previously reported c.279C>G (p.Phe93Leu, two families) mutation in DNAJB6 were identified. All showed a reduced capacity to prevent protein aggregation. CONCLUSIONS: The mutational and phenotypical spectrum of DNAJB6-caused muscle disease is larger than previously reported, including also dysphagia. The originally reported c.279C>G (p.Phe93Leu) mutation is now identified in four different populations and appears to be a mutational hotspot. Our report confirms that some DNAJB6 mutations cause distal-onset myopathy and hence DNAJB6 defects should be considered broadly in dominant muscular dystrophy families.

Association study reveals novel risk loci for sporadic inclusion body myositis.

BACKGROUND AND PURPOSE: The aim was to identify potential genetic risk factors associated with sporadic inclusion body myositis (sIBM). METHODS: An association based case-control approach was utilized on whole exome sequencing data of 30 Finnish sIBM patients and a control cohort (n = 193). A separate Italian cohort of sIBM patients (n = 12) was used for evaluation of the results. RESULTS: Seven single nucleotide polymorphisms were identified in five genes that have a considerably higher observed frequency in Finnish sIBM patients compared to the control population, and the previous association of the genetic human leukocyte antigen region was confirmed. CONCLUSIONS: All seven identified variants could individually or in combination increase the susceptibility for sIBM.

Myofibrillar and distal myopathies.

Distal myopathies and myofibrillar myopathies are both rare subcategories of muscle diseases. Myofibrillar myopathies are genetically heterogeneous group of diseases characterized by distinctive histopathology of abnormal protein aggregations and myofibrillar disintegration. All genes causing myofibrillar myopathy encode proteins that either reside in or associate with the Z-disc. Distal myopathies are also genetically heterogeneous muscular dystrophies in which muscle weakness presents distally in the feet and/or hands. A subgroup of distal myopathies, desminopathy, distal myotilinopathy, ZASPopathy and alpha-B crystallin-mutated distal myopathy, belong to myofibrillar myopathies and show similar pathological changes in muscle biopsies. Common features of these diseases are dominant inheritance and adult-onset of symptoms starting in the feet and slowly progressing to encompass other muscle groups. Cardiomyopathy is not a common feature in distal MFM myopathies.

Myofibrillar myopathies: State of the art, present and future challenges.

Myofibrillar myopathies (MFM) have been described in the mid-1990s as a group of diseases sharing common histological features, including an abnormal accumulation of intrasarcoplasmic proteins, the presence of vacuoles and a disorganization of the intermyofibrillar network beginning at the Z-disk. The boundaries of this concept are still uncertain, and whereas six genes (DES, CRYAB, LDB3/ZASP, MYOT, FLNC and BAG3) are now classically considered as responsible for MFM, other entities such as FHL1 myopathy or Hereditary Myopathy with Early Respiratory Failure linked to mutations of titin can now as well be included in this group. The diagnosis of MFM is not always easy; as histological lesions can be focal, and muscle biopsy may be disappointing; this has led to a growing importance of muscle imaging, and the selectivity of muscle involvement has now been described in several disorders. Due to the rarity of these myopathies, if some clinical patterns (such as distal myopathy associated with cardiomyopathy due to desmin mutations) are now well known, surprises remain possible and should lead to systematic testing of the known genes in case of a typical histological presentation. In this paper, we aim at reviewing the data acquired on the six main genes listed above as well as presenting the experience from two French reference centres, Paris and Marseilles.

Altered expression and splicing of Ca(2+) metabolism genes in myotonic dystrophies DM1 and DM2.

AIMS: Myotonic dystrophy types 1 and 2 (DM1 and DM2) are multisystem disorders caused by similar repeat expansion mutations, with similar yet distinct clinical features. Aberrant splicing of multiple effector genes, as well as dysregulation of transcription and translation, has been suggested to underlie different aspects of the complex phenotypes in DM1 and DM2. Ca(2+) plays a central role in both muscle contraction and control of gene expression, and recent expression profiling studies have indicated major perturbations of the Ca(2+) signalling pathways in DM. Here we have further investigated the expression of genes and proteins involved in Ca(2+) metabolism in DM patients, including Ca(2+) channels and Ca(2+) binding proteins. METHODS: We used patient muscle biopsies to analyse mRNA expression and splicing of genes by microarray expression profiling and RT-PCR. We studied protein expression by immunohistochemistry and immunoblotting. RESULTS: Most of the genes studied showed mRNA up-regulation in expression profiling. When analysed by immunohistochemistry the Ca(2+) release channel ryanodine receptor was reduced in DM1 and DM2, as was calsequestrin 2, a sarcoplasmic reticulum lumen Ca(2+) storage protein. Abnormal splicing of ATP2A1 was more pronounced in DM2 than DM1. CONCLUSIONS: We observed abnormal mRNA and protein expression in DM affecting several proteins involved in Ca(2+) metabolism, with some differences between DM1 and DM2. Our protein expression studies are suggestive of a post-transcriptional defect(s) in the myotonic dystrophies.

'Pathognomonic' muscle imaging findings in DNAJB6 mutated LGMD1D.

BACKGROUND AND PURPOSE: We have previously reported clinical, genetic and molecular pathomechanistic findings in DNAJB6 mutated LGMD1D. After publishing clinical findings of the original Finnish family we identified more Finnish, Italian and US families with the same disease, ultimately confirmed by mutations in the same gene. METHODS: Of the total number of 28 examined Finnish and Italian patients 23 underwent lower limb muscle imaging. RESULTS: At the early stages of the disease fatty degeneration in T1-weighed MRI sequences were observed in the soleus, adductor magnus, semimembranosus and biceps femoris muscles followed by medial gastrocnemius, adductor longus and later by vasti muscles of the quadriceps. Rectus femoris, lateral gastrocnemius, sartorius, gracilis and the anterolateral group of the lower leg muscles were spared until late senecence. The pattern of differential involvement could be identified at different stages of the disease process. CONCLUSIONS: Since the general clinical findings do not provide clues for diagnosis this distinct pattern of muscle involvement and pathognomonic imaging findings are highly relevant in the clinical setting. The pattern of muscle involvement is so typical that it can be used as a differential diagnostic tool for LGMD1D. The final diagnosis however requires molecular genetic confirmation.

Spanish MYH7 founder mutation of Italian ancestry causing a large cluster of Laing myopathy patients.

Laing myopathy is a distal myopathy caused by mutations in the tail of the slow beta-myosin heavy chain gene MYH7. A large cluster of patients belonging to different families, with Laing myopathy due to p.K1729del mutation, was found in the Safor region, Spain. The same mutation was previously reported in an American family with Italian ancestry. The possibility that p.K1729del in MYH7 might be a founder mutation in the Safor patients and the chance of a common origin with the Italian-American family mutation was investigated by haplotype analyses, mutation data origin estimation and historical inquiry. Our results show that the p.K1729del in MYH7 harboured by patients from the Safor indeed is a founder mutation. A common ancestral origin of this mutation in the Spanish and Italian families is also suggested because they all share a core SNP haplotype at locus MYH7. Data estimation yields the origin of the mutation in the Safor at the beginning of the XVII century, when the Moorish were spelt and the region was resettled with Italian families.

Myopathies caused by homozygous titin mutations: limb-girdle muscular dystrophy 2J and variations of phenotype.

Limb-girdle muscular dystrophy 2J caused by mutations in C-terminal titin has so far been identified in Finnish patients only. This may in part be due to limited availability of diagnostic tests for titin defects. In this report, a French family with an autosomal-dominant late-onset distal myopathy of the tibial muscular dystrophy phenotype segregating in several members of the family was described. One deceased patient in the family proved to be homozygous for the C-terminal truncating titin mutation because of consanguinity. According to available medical records, the patient had a clearly more severe generalised muscle weakness and atrophy phenotype not recognised as a distal myopathy at the time. Autopsy findings in one of the original Finnish limb-girdle muscular dystrophy 2J patients were reported and the early phenotype in a newly identified young patient with homozygous Finnish C-terminal titin mutation (FINmaj) was detailed.

Mutations in CHMP2B are not a cause of frontotemporal lobar degeneration in Finnish patients.

BACKGROUND: Frontotemporal lobar degeneration (FTLD) is a genetically complex disorder. The majority of mutations linked to FTLD families are found in the microtubule-associated protein tau (MAPT) and progranulin (PGRN) genes. Mutations in the chromatin-modifying protein 2B gene (CHMP2B) have been identified in a few families. However, CHMP2B has been showed to be a rare cause of FTLD. Our aim was to determine the frequency of CHMP2B mutations in a clinical series of patients with FTLD in Northern Finland. PATIENTS AND METHODS: We examined 72 (36 men) Finnish patients with FTLD. The mean age at onset was 58.9 (range 43­80). Symptoms of motor neuron disease (FTLDMND) were present in 12 patients (17%). Positive family history was detected in 28% of the patients. Mutations in MAPT and PGRN were excluded from these patients. All exons and exon­intron boundaries of the CHMP2B gene were sequenced. RESULTS: No pathogenic CHMP2B mutations were found. A rare polymorphism in the non-coding region of exon 1 (rs36098294) and three other previously reported polymorphisms were detected. CONCLUSIONS: Our results confirm that mutations in CHMP2B are not a common cause of FTLD. MAPT and PGRN mutations are also rare in Finnish population, suggesting that other, still unknown genetic factors may play a role in the pathogenesis of FTLD in Finnish population.

Low prevalence of progranulin mutations in Finnish patients with frontotemporal lobar degeneration.

BACKGROUND AND PURPOSE: Mutations in the progranulin (PGRN) gene have recently been associated with frontotemporal lobar degeneration (FTLD). The frequency of these mutations varies between populations. The aim of this study was to determine mutations and genetic variations of the PGRN gene in Finnish patients with FTLD and FTLD with associated motor neuron disease (FTLD-MND). SUBJECTS AND METHODS: All exons of the PGRN gene were sequenced from 69 Finnish patients with FTLD. The FTLD-MND phenotype was present in 13 of the 69 patients. RESULTS: No pathogenic PGRN mutations were identified in the cohort. Eleven sequence variations were detected, of which IVS8 + 15C>T, IVS4-51_-52insAGTC and IVS11 + 25G>A have not been reported previously. At least one single-nucleotide polymorphism (SNP) of PGRN was detected in 83% of patients. CONCLUSIONS: We conclude that mutations in PGRN are rare among Finnish patients with FTLD and FTLD-MND. However, SNPs were frequent suggesting high genetic variability of the PGRN gene.

Electron microscopy in myofibrillar myopathies reveals clues to the mutated gene.

We studied the ultrastructural characteristics in patients with myofibrillar myopathy (MFM) and differentiated between MFM-subtypes using electron microscopic (EM) findings. The ultrastructural findings in 19 patients with different genetically proven MFMs (9 desmin, 5 alphaB-crystallin, 3 ZASP, 2 myotilin) were analyzed. In one ZASPopathy, we additionally performed an immunoEM study, using antibodies against desmin, alphaB-crystallin, ZASP and myotilin. The ultrastructural findings in desminopathies and alphaB-crystallinopathies were very similar and consisted of electrondense granulofilamentous accumulations and sandwich formations. They differed in the obvious presence of early apoptotic nuclear changes in alphaB-crystallinopathies. ZASPopathies were characterized by filamentous bundles (labeled with the myotilin antibody on immunoEM), and floccular accumulations of thin filamentous material. Tubulofilamentous inclusions in sarcoplasm and myonuclei in combination with filamentous bundles were characteristic for myotilinopathies. We conclude that MFMs ultrastructural findings can direct diagnostic efforts towards the causal gene mutated, and that EM should be included in the diagnostic workup of MFMs.

High frequency of co-segregating CLCN1 mutations among myotonic dystrophy type 2 patients from Finland and Germany.

Based on previous reports the frequency of co-segregating recessive chloride channel (CLCN1) mutations in families with myotonic dystrophy type 2 (DM2) was suspected to be increased. We have studied the frequency of CLCN1 mutations in two separate patient and control cohorts from Germany and Finland, and for comparison in a German myotonic dystrophy type 1 (DM1) patient cohort. The frequency of heterozygous recessive chloride channel (CLCN1) mutations is disproportionally higher (5 %) in currently diagnosed DM2 patients compared to 1.6 % in the control population (p = 0.037), while the frequency in DM1 patients was the same as in the controls. Because the two genes segregate independently, the prevalence of CLCN1 mutations in the total DM2 patient population is, by definition, the same as in the control population. Our findings are, however, not based on the total DM2 population but on the currently diagnosed DM2 patients and indicate a selection bias in molecular diagnostic referrals. DM2 patients with co-segregating CLCN1 mutation have an increased likelihood to be referred for molecular diagnostic testing compared to DM2 patients without co-segregating CLCN1 mutation.

EFNS guidelines for the use of intravenous immunoglobulin in treatment of neurological diseases: EFNS task force on the use of intravenous immunoglobulin in treatment of neurological diseases.

Despite high-dose intravenous immunoglobulin (IVIG) is widely used in treatment of a number of immune-mediated neurological diseases, the consensus on its optimal use is insufficient. To define the evidence-based optimal use of IVIG in neurology, the recent papers of high relevance were reviewed and consensus recommendations are given according to EFNS guidance regulations. The efficacy of IVIG has been proven in Guillain-Barré syndrome (level A), chronic inflammatory demyelinating polyradiculoneuropathy (level A), multifocal mononeuropathy (level A), acute exacerbations of myasthenia gravis (MG) and short-term treatment of severe MG (level A recommendation), and some paraneoplastic neuropathies (level B). IVIG is recommended as a second-line treatment in combination with prednisone in dermatomyositis (level B) and treatment option in polymyositis (level C). IVIG should be considered as a second or third-line therapy in relapsing-remitting multiple sclerosis, if conventional immunomodulatory therapies are not tolerated (level B), and in relapses during pregnancy or post-partum period (good clinical practice point). IVIG seems to have a favourable effect also in paraneoplastic neurological diseases (good practice point) [corrected],stiff-person syndrome (level A), some acute-demyelinating diseases and childhood refractory epilepsy (good practice point).

Zaspopathy in a large classic late-onset distal myopathy family.

Distal myopathies have been associated with mutations in titin, dysferlin, GNE, desmin and myosin. Of these, only titin mutations were previously known to cause dominant late-onset distal myopathy. Recent findings, however, have indicated that patients affected with myofibrillar myopathy have a more distal than proximal muscle phenotype and a proportion of these may have mutations in myotilin, ZASP or filamin C, besides previously known desmin and alphaB-crystallin. Here we report that the disorder in one of the well-characterized autosomal dominant distal myopathy families, the Markesbery et al. family, first reported in 1974, is caused by ZASP mutation A165V. Previous linkage to the titin locus 2q31 proved incorrect. ZASP expression by immunoblotting shows normal presence of the main 32 and 78 kDa bands and immunohistochemistry in patients reveals normal Z-disc localization except for moderate accumulations together with myotilin, desmin alphaB-crystallin and alpha-actinin. Muscle imaging reveals involvement in both the posterior and anterior compartments of the lower leg and considerable affection of proximal leg muscles at later stages. Haplotype studies in this family and in five other unrelated families with European ancestry carrying the identical A165V mutation share common markers at the locus suggesting the existence of a founder mutation.

GNE-Myopathy in a Greek Romani Family with Unusual Calf Phenotype and Protein Aggregation Pathology.

BACKGROUND: GNE-myopathy is increasingly diagnosed in different ethnicities worldwide. No clear genotype-phenotype correlation has been established to date. CASE REPORTS: We describe two affected members of the same family from Balkan population carrying an already known homozygous pathogenic mutation in the kinase domain of the UDP-N-acetylglucosamine 2 epimerase/N-acetylmannosamime kinase (GNE) gene. The patients presented with severe distal weakness of lower legs combined with rimmed vacuoles in muscle biopsy. However, in contrast to the typical pattern of muscle involvement, one of them showed severe involvement of posterior calf muscles with spared anterior compartment of the lower leg muscles. CONCLUSIONS: These patients provide evidence for a larger variability and further extend the phenotypic spectrum of GNE-myopathy to include preferential calf involvement.

Founder effect in spinal and bulbar muscular atrophy (SBMA) in Scandinavia.

We haplotyped 13 Finnish, 10 Swedish, 12 Danish and 2 Norwegian SBMA (spinal and bulbar muscular atrophy, Kennedy disease) families with a total of 45 patients and 7 carriers for 17 microsatellite markers spanning a 25.2 cM region around the androgen receptor gene on chromosome Xq11-q12 in search of a genetic founder effect. In addition, the haplotypes of 50 Finnish, 20 Danish and 22 Swedish control males were examined. All the Scandinavian SBMA families shared the same 18 repeat allele for the intragenic GGC repeat, which was present in only 24% of the controls. Linkage disequilibrium was also seen for the closest microsatellite markers. In addition, extended haplotypes of the Finnish, Swedish and Danish SBMA families revealed country-specific common founder haplotypes, which over time became gradually shortened by recombinations. No common haplotype was found among the controls. The data suggest that the SBMA mutation was introduced into western Finland 20 generations ago. Haplotype analysis implies a common ancestor for the majority of Scandinavian SBMA patients.