Body composition, muscle strength, and physical function of patients with Bethlem myopathy and Ullrich congenital muscular dystrophy.

Maria Teresa Miscione,Luciano Merlini,Riccardo Orsini,Daniela Cocchi,Francesca Bruno,Cesare Faldini,Claudio Ripamonti,Giuliana Nervuti,Massimo Pellegrini

doi:10.1155/2013/152684

Abstract

Objective. To determine the contributions of body mass, adiposity, and muscularity to physical function and muscle strength in adult patients with Bethlem myopathy (BM) and Ullrich congenital muscular dystrophy (UCMD). Materials and Methods. Evaluation involved one UCMD and 7 BM patients. Body composition was determined by body mass index (BMI) and dual-energy-X-ray-absorptiometry (DXA), muscle strength by dynamometry, physical function by the distance walked in 6 minutes (6MWD), forced vital capacity (FVC) by a spirometer. Results. Six participants were of normal weight and 2 overweight based on BMI; all were sarcopenic based on appendicular fat free mass index (AFFMI); and 7 were sarcopenic obese based on AFFMI and % fat mass. Average muscle strength was reduced below 50% of normal. The 6MWD was in BM patients 30% less than normal. FVC was reduced in 4 of the BM patients. Muscle strength had a good correlation with the physical function variables. Correlation between muscle strength and BMI was poor; it was very high with AFFMI. AFFMI was the best single explicator of muscle strength and physical function. Conclusion. Muscle mass determined by DXA explains most of the variability of the measures of muscle strength and physical function in patients with BM and UCMD.

Highlights

Mutations in any of the three genes (COL6A1, COL6A2, and COL6A3) coding for collagen VI, a major extracellular matrix protein of the endomysium of skeletal muscles, cause the collagen VI-related myopathies [1] including Bethlem myopathy (BM), Ullrich congenital muscular dystrophy (UCMD), and the two rarer variants limb girdle and myosclerosis myopathy [2, 3]
We reviewed the records of our 75 patients with a clinical/ laboratory phenotype compatible with the diagnosis of BM/ UCMD [7]
Body Composition. 6 participants were of normal weight and 2 were overweight based on body mass index (BMI), all were sarcopenic

Summary

Introduction

Mutations in any of the three genes (COL6A1, COL6A2, and COL6A3) coding for collagen VI, a major extracellular matrix protein of the endomysium of skeletal muscles, cause the collagen VI-related myopathies [1] including Bethlem myopathy (BM), Ullrich congenital muscular dystrophy (UCMD), and the two rarer variants limb girdle and myosclerosis myopathy [2, 3]. Bethlem myopathy is a congenital or early-onset muscular dystrophy characterized by axial and proximal muscle weakness [4, 5], and the hallmark of the disease is the presence of contractures of the interphalangeal joints of the last four fingers [6]. Respiratory failure is part of the clinical spectrum and can occur in patients with preserved ambulatory function [8]. UCMD is a severe congenital muscular dystrophy characterized by early onset, generalized and rapidly progressive muscle wasting and weakness, proximal joint contractures, and distal joint hyperflexibility.

Methods

Discussion

Conclusion