calpain and Neuromuscular-Diseases

The most common autosomal recessive limb girdle muscular dystrophy is associated with the CAPN3 gene. The exclusively recessive inheritance of this disorder has been recently challenged by the description of the recurrent variants, c.643_663del21 [p.(Ser215_Gly221del)] and c.598_612del15 [p.(Phe200_Leu204del)], associated with autosomal dominant inheritance. Our objective was to confirm the existence of autosomal dominant calpainopathies.. Through our activity as one of the reference centres for genetic diagnosis of calpainopathies in France and the resulting collaborations through the French National Network for Rare Neuromuscular Diseases (FILNEMUS), we identified four families harbouring the same CAPN3 heterozygous variant with supposedly autosomal dominant inheritance.. We identified a novel dominantly inherited CAPN3 variant, c.1333G>A [p.(Gly445Arg)] in 14 affected patients from four unrelated families. The complementary phenotypic, functional and genetic findings correlate with an autosomal dominant inheritance in these families, emphasizing the existence of this novel transmission mode for calpainopathies. The mild phenotype associated with these autosomal dominant cases widens the phenotypic spectrum of calpainopathies and should therefore be considered in clinical practice.. We confirm the existence of autosomal dominant calpainopathies as an entity beyond the cases related to the in-frame deletions c.643_663del21 and c.598_612del15, with the identification of a novel dominantly inherited and well-documented CAPN3 missense variant, c.1333G>A [p.(Gly445Arg)]. In addition to the consequences for genetic counselling, the confirmation of an autosomal dominant transmission mode for calpainopathies underlines the importance of re-assessing other myopathies for which the inheritance is considered as strictly autosomal recessive.

Topics: Adolescent; Adult; Aged; Aged, 80 and over; Calpain; Chromosome Aberrations; Female; France; Genes, Dominant; Genetic Variation; Humans; Male; Middle Aged; Muscle Proteins; Mutation; Neuromuscular Diseases; Pedigree; Phenotype; Young Adult

Limb girdle muscular dystrophies are rare genetic diseases. Despite constant progress in genetics and biochemistry, the pathogenic mechanisms are not completely understood. Calpainopathy (LGMD2A) has been reported to be the most frequent autosomal recessive form of muscular dystrophy in several populations. Point mutations in CAPN3 are difficult to identify and the analysis is long and costly. The use of western blot does not seem to provide the expected sensitivity and specificity.. We studied all the patients diagnosed in the neuromuscular center of Bordeaux (France) with confirmed calpainopathy in order to establish the appropriate diagnostic approach (inclusion criteria: muscular biopsy with calpain 3 western blot study, two mutations in CAPN3). Patients with highly suspected calpainopathy (same criteria with only one mutation) were also analyzed.. Our 13 patients belonged to 10 different families. Four patients had a normal western blot for calpain (WBn). We found high phenotypic variability with frequent atypical signs. The WBn group had less severe disease (a statistically significant later age of onset, a tendency toward lower CK levels and a slower disease course). We extended this comparison to the single mutation patients and we found the same results.. Considering the lack of sensitivity of western blot protein analysis in LGMD2A, a normal western blot for calpain should not halt the genetic analysis. The western blot result seems to have prognostic value. A normal western blot may help genetic testing by highlighting some mutational hot spots in the CAPN3 gene.

Topics: Adolescent; Adult; Age of Onset; Blotting, Western; Calpain; Child; Cohort Studies; Disability Evaluation; Disease Progression; Female; Humans; Male; Middle Aged; Muscle Proteins; Muscular Dystrophies, Limb-Girdle; Neuromuscular Diseases; Phenotype; Point Mutation; Prognosis; Young Adult

Mutations in the gene encoding muscle-specific calpain 3 protease cause limb girdle muscular dystrophy type 2A. Calpainopathy is characterised by progressive symmetrical atrophy of pelvic, scapular and trunk muscles with an elevated creatine kinase. Most patients develop symptoms in childhood and lose the ability to walk by the age of 40 years. We describe a man who presented with foot drop at the age of 41 years, together with neurophysiological, histopathological and genetic data. This is the first report of calpainopathy presenting as foot drop, and widens the phenotype associated with this disease.

Topics: Adult; Blotting, Western; Calpain; Creatine Kinase; DNA; Electromyography; Exons; Foot; Humans; Magnetic Resonance Imaging; Male; Muscle Proteins; Muscle Weakness; Muscle, Skeletal; Muscular Dystrophies, Limb-Girdle; Neural Conduction; Neuromuscular Diseases; Spine

Mutations in the dysferlin gene cause muscular dystrophies called dysferlinopathy, which include limb-girdle muscular dystrophy type 2B (LGMD2B) and Miyoshi myopathy (MM). To clarify the frequency, clinicopathological and genetic features of dysferlinopathy in Japan, we performed protein and gene analyses of dysferlin. We examined a total of 107 unrelated Japanese patients, including 53 unclassified LGMD, 28 MM and 26 other neuromuscular disorders (ONMD). Expression of dysferlin protein was observed using immunohistochemistry (IHC) and mini-multiplex Western blotting (MMW), and mutation analysis was performed. We found a deficiency of dysferlin protein by both IHC and MMW in 19% of LGMD and 75% of MM patients, and mutations in the dysferlin gene were identified in this group alone. 19% of dysferlin-deficient patients had 3370G-->T missense mutation and 16% had 1939C-->G nonsense mutation. The patients with homozygous 3370G-->T mutation showed milder clinical phenotypes. Twenty-five percent of MM muscles had normal dysferlin protein contents that suggested the genetic heterogeneity of this disease. Altered immunolocalization of dysferlin was observed in not only primary dysferlinopathy, but also in the several diseased muscles with normal protein contents. This result implies the necessity of other protein(s) for proper membrane localization of dysferlin, or some roles of dysferlin in the cytoplasmic region.

Topics: Age of Onset; Alanine; Blotting, Western; Calpain; Cysteine; Cytoskeletal Proteins; DNA Mutational Analysis; Dysferlin; Dystroglycans; Dystrophin; Glycine; Humans; Immunohistochemistry; Japan; Membrane Glycoproteins; Membrane Proteins; Muscle Proteins; Muscle, Skeletal; Muscular Dystrophies; Mutation; Neuromuscular Diseases; Sarcoglycans; Sequence Analysis, Protein; Tyrosine

The molecular events by which eccentric muscle contractions induce muscle damage and remodelling remain largely unknown. We assessed whether eccentric exercise modulates the expression of proteinases (calpains 1, 2 and 3, proteasome, cathepsin B+L), muscle structural proteins (alpha-sarcoglycan and desmin), and the expression of the heat shock proteins Hsp27 and alphaB-crystallin. Vastus lateralis muscle biopsies from twelve healthy male volunteers were obtained before, immediately after, and 1 and 14 days after a 30 min downhill treadmill running exercise. Eccentric exercise induced muscle damage as evidenced by the analysis of muscle pain and weakness, creatine kinase serum activity, myoglobinaemia and ultrastructural analysis of muscle biopsies. The calpain 3 mRNA level was decreased immediately after exercise whereas calpain 2 mRNA level was increased at day 1. Both mRNA levels returned to control values by day 14. By contrast, cathepsin B+L and proteasome enzyme activities were increased at day 14. The alpha-sarcoglycan protein level was decreased immediately after exercise and at day 1, whereas the desmin level peaked at day 14. alphaB-crystallin and Hsp27 protein levels were increased at days 1 and 14. Our results suggest that the differential expression of calpain 2 and 3 mRNA levels may be important in the process of exercise-induced muscle damage, whereas expression of alpha-sarcoglycan, desmin, alphaB-crystallin and Hsp27 may be essentially involved in the subsequent remodelling of myofibrillar structure. This remodelling response may limit the extent of muscle damage upon a subsequent mechanical stress.

Topics: Actins; Adaptation, Physiological; Adult; alpha-Crystallins; beta-Crystallins; Calpain; Cysteine Endopeptidases; Cytoskeletal Proteins; Desmin; Exercise; Gene Expression; Heat-Shock Proteins; HSP27 Heat-Shock Proteins; Humans; Lysosomes; Male; Membrane Glycoproteins; Molecular Chaperones; Multienzyme Complexes; Muscle Contraction; Muscle Proteins; Muscle, Skeletal; Neoplasm Proteins; Neuromuscular Diseases; Proteasome Endopeptidase Complex; RNA, Messenger; Running; Sarcoglycans; Stress, Mechanical