Early and consistent pattern of proximal weakness in GNE myopathy.

ABSTRACT

BACKGROUND: GNE myopathy is widely regarded as a distal myopathy. Involvement of proximal musculature in this condition has not been systematically studied. METHODS: The phenotype of genetically confirmed patients with GNE myopathy was analyzed. Fourteen groups of muscles were evaluated with Medical Research Council (MRC) grading and the average muscle scores (AMS1-10) were calculated. RESULTS: Fully documented AMS data was available in 31 of 65 patients. It showed a consistent pattern of severe weakness of hip adductors, hip flexors, knee flexors, and foot dorsiflexors, with milder weakness of the hip extensors and abductors. The knee extensors were largely unaffected. The proximal weakness appeared early in the course of the disease. Proximal muscle weakness was also present in the remaining 34 patients in whom the data were limited. A variant in exon 13 (c.2179G > A) was very common (81.5%). CONCLUSIONS: The GNE phenotype in this Indian cohort exhibited mixed proximal and distal involvement. Weakness of adductors and flexors of the hip formed an integral part of the phenotype.