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Novel variant in the PYGM gene causing late‐onset limb‐girdle myopathy, ptosis, and camptocormia
Author(s) -
Chéraud Chrystel,
Froissart Roseline,
Lannes Béatrice,
EchanizLaguna Andoni
Publication year - 2018
Publication title -
muscle and nerve
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.025
H-Index - 145
eISSN - 1097-4598
pISSN - 0148-639X
DOI - 10.1002/mus.25588
Subject(s) - muscle biopsy , myopathy , exercise intolerance , medicine , atrophy , gene mutation , mutation , genetics , biology , biopsy , gene , heart failure
McArdle disease is a glycogen storage disease caused by mutations in the PYGM gene encoding myophosphorylase. It manifests classically with childhood‐onset exercise‐induced pain. Methods We report the characteristics of 2 unrelated patients with a new homozygous mutation of the PYGM gene. Results Two patients, aged 76 and 79 years, presented with severe upper and lower limb atrophy and weakness. Additionally, 1 patient presented with bilateral ptosis, and the other with camptocormia. In both patients, symptoms had developed progressively in the 2 preceding years, and there was no history of exercise intolerance. Both patients demonstrated myogenic abnormalities on electromyography, multiple glycogen‐containing vacuoles and undetectable muscle myophosphorylase activity on muscle biopsy, and a novel homozygous frameshift p.Lys42Profs*48 PYGM mutation. Conclusions This report expands the phenotype and genotype of McArdle disease and suggests that PYGM mutations should be looked for in patients with very late‐onset myopathy with no previous history of exercise intolerance. Muscle Nerve 57 : 157–160, 2018