title: A novel MYH7 mutation occurring independently in French and Norwegian Laing distal myopathy families and de novo in one Finnish patient.
abstract: Laing early-onset distal myopathy is a rare autosomal dominant myopathy and caused by mutations in the MYH7 gene, encoding the slow beta myosin heavy chain. We report the first molecularly verified Laing distal myopathy in a French family caused by a novel p.Glu1508del mutation in the MYH7 gene. Interestingly, we identified the identical mutation in an unrelated Norwegian family and, as a de novo mutation, in one sporadic Finnish patient. Described in detail are the clinical and electrophysiological characteristics of 5 patients from the French family. The phenotype in the Finnish patient and the Norwegian patients is largely similar. This mutation causes a benign myopathy within the range of previously reported Laing myopathy phenotype variations. Onset of weakness in the tibialis anterior (TA) muscles occurred in early childhood in all patients. Finger extensor and neck flexor weakness together with Achilles tendon retractions were other frequent findings. The independent recurrence of the identical mutation without any founder background may reflect a mutational susceptibility of this residue, in accordance with some other MYH7 mutations previously reported. De novo mutations seem to be frequent in Laing distal myopathy. This is of clinical importance since a dominant family history is missing, which may confuse differential diagnostic efforts.
authors.affiliation: Centre de Référence des Maladies Neuromusculaires Paris-Est, Institut de Myologie, Groupe Hospitalier Pitié-Salpêtrière, Assistance Publique des Hôpitaux de Paris, Paris, France. odile.dubourg@psl.aphp.fr
authors.forename: Odile
authors.initials: O
authors.lastname: Dubourg
authors.forename: Thierry
authors.initials: T
authors.lastname: Maisonobe
authors.forename: Anthony
authors.initials: A
authors.lastname: Behin
authors.forename: Tiina
authors.initials: T
authors.lastname: Suominen
authors.forename: Olayinka
authors.initials: O
authors.lastname: Raheem
authors.forename: Sini
authors.initials: S
authors.lastname: Penttilä
authors.forename: Matt
authors.initials: M
authors.lastname: Parton
authors.forename: Bruno
authors.initials: B
authors.lastname: Eymard
authors.forename: Arve
authors.initials: A
authors.lastname: Dahl
authors.forename: Bjarne
authors.initials: B
authors.lastname: Udd
mesh_terms: D000251:Adenosine Triphosphatases / Q000378:metabolism; D000328:Adult; D024722:Cardiac Myosins / Q000235:genetics*; D002675:Child, Preschool; D049310:Distal Myopathies / Q000235:genetics*; D004576:Electromyography / Q000379:methods; D005192:Family Health; D005260:Female; D005602:France / Q000208:ethnology; D005998:Glycine / Q000235:genetics; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000473:pathology; D009206:Myocardium / Q000473:pathology; D018995:Myosin Heavy Chains / Q000235:genetics*; D017384:Sequence Deletion / Q000235:genetics; D019680:Trinucleotide Repeat Expansion / Q000235:genetics; D044465:White People; D055815:Young Adult
chemical_list: C501641:MYH7 protein, human; D000251:Adenosine Triphosphatases; D024722:Cardiac Myosins; D018995:Myosin Heavy Chains; D005998:Glycine