Generalized muscle pseudo-hypertrophy and stiffness associated with the myotilin Ser55Phe mutation: a novel myotilinopathy phenotype?
Myotilinopathies are a group of muscle disorders caused by mutations in the MYOT gene. It was first described in two families suffering from limb girdle muscle dystrophy type 1 (LGMD 1A), and later identified in a subset of dominant or sporadic patients suffering from myofibrillar myopathy, as well as in a family with spheroid body myopathy. Disease phenotypes associated with MYOT mutations are clinically heterogeneous and include pure LGMD forms as well as late-onset distal myopathies. We report here on a 53-year-old male suffering from a unique clinical profile characterized by generalized symmetrical increase in muscle bulk leading to a Herculean appearance. Muscle weakness and stiffness in the lower extremities were the patient's main complaints. Muscle MRI showed extensive fatty infiltration in the thigh and leg muscles and a muscle biopsy showed a myofibrillar myopathy with prominent protein aggregates. Gene sequencing revealed a Ser55Phe missense mutation in the myotilin gene. The mutation was identified in his older brother, who presented a mild hypertrophic appearance and had a myopathic pattern in EMG, despite not presenting any of the complaints of the proband and having normal muscle strength. This finding, and his deceased father and paternal aunt's similar gait disorders, suggest that this is in fact a new autosomal dominant kindred. The present observations further expand the spectrum of clinical manifestations associated with mutations in the myotilin gene.
Gamez
Josep
J
Neurology Department, Hospital Universitari Vall d'Hebron, Autonomous University of Barcelona, Barcelona, Spain. 12784jgc@comb.es
Armstrong
Judith
J
Shatunov
Alexey
A
Selva-O'Callaghan
Albert
A
Dominguez-Oronoz
Rosa
R
Ortega
Arantxa
A
Goldfarb
Lev
L
Ferrer
Isidre
I
Olivé
Montse
M
D001706:Biopsy; D064211:Connectin; D003598:Cytoskeletal Proteins / Q000235:genetics*; D005192:Family Health; D006801:Humans; D006984:Hypertrophy; D008279:Magnetic Resonance Imaging; D008297:Male; D008840:Microfilament Proteins; D008875:Middle Aged; D009124:Muscle Proteins / Q000235:genetics*; D009127:Muscle Rigidity / Q000235:genetics* / Q000473:pathology*; D018908:Muscle Weakness / Q000235:genetics / Q000473:pathology; D009135:Muscular Diseases / Q000235:genetics* / Q000473:pathology*; D010641:Phenotype; D017354:Point Mutation
D064211:Connectin; D003598:Cytoskeletal Proteins; C577290:MYOT protein, human; D008840:Microfilament Proteins; D009124:Muscle Proteins