title: New phenotype and pathology features in MYH7-related distal myopathy.
abstract: Laing distal myopathy is an autosomal dominant disease due to mutations in the gene encoding for the human slow-β myosin heavy chain, MYH7. Most reports describe it as a mild, early onset myopathy with involvement usually restricted to foot extensors, hand finger extensors and neck flexors, and unspecific findings on muscle biopsy. We identified the first two Italian families with Laing distal myopathy, harboring two novel mutations in the MYH7 gene and performed clinical, neurophysiological, pathological, muscle MRI and cardiological investigations on affected members from the two families. Subjects from one family presented a moderate-severe phenotype, with proximal together with distal involvement and even loss of ambulation at advanced age. One patient displayed atypical muscle biopsy findings including cytoplasmic bodies and myofibrillar myopathy-like features. Affected members from the second family shared a very mild phenotype, with weakness largely limited to long toe and foot extensors and/or late onset. No patient showed any sign of heart involvement. Our study significantly broadens the clinical and pathological spectrum of Laing distal myopathy. We suggest that MYH7 screening should be considered in undiagnosed late-onset distal myopathy or cytoplasmic body myopathy patients.
authors.affiliation: Don Carlo Gnocchi Onlus Foundation, Italy. tasca.giorgio@virgilio.it
authors.forename: Giorgio
authors.initials: G
authors.lastname: Tasca
authors.forename: Enzo
authors.initials: E
authors.lastname: Ricci
authors.forename: Sini
authors.initials: S
authors.lastname: Penttilä
authors.forename: Mauro
authors.initials: M
authors.lastname: Monforte
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Giglio
authors.forename: Pierfrancesco
authors.initials: P
authors.lastname: Ottaviani
authors.forename: Giovanni
authors.initials: G
authors.lastname: Camastra
authors.forename: Gabriella
authors.initials: G
authors.lastname: Silvestri
authors.forename: Bjarne
authors.initials: B
authors.lastname: Udd
mesh_terms: D000328:Adult; D000368:Aged; D024722:Cardiac Myosins / Q000235:genetics*; D004252:DNA Mutational Analysis; D049310:Distal Myopathies / Q000235:genetics / Q000473:pathology / Q000503:physiopathology; D005192:Family Health; D005260:Female; D006801:Humans; D007558:Italy; D008279:Magnetic Resonance Imaging; D008297:Male; D046529:Microscopy, Electron, Transmission; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000473:pathology* / Q000648:ultrastructure; D009154:Mutation / Q000235:genetics*; D018995:Myosin Heavy Chains / Q000235:genetics*
chemical_list: C501641:MYH7 protein, human; D024722:Cardiac Myosins; D018995:Myosin Heavy Chains