[Collagenopathy (Ullrich congenital muscular dystrophy, Bethlem myopathy)]

Abstract

Collagenopathies with collagen VI mutations include Ullrich congenital muscular dystrophy (Ullrich's disease) and Bethlem myopathy. Patients with Ullrich's disease have generalized muscle weakness, multiple contractures of the proximal joints and hyperextensibility of the distal joints. Bethlem myopathy is characterized by the combination of proximal muscle weakness and contractures of finger, elbow, and ankle joints. We found for the first time a deficiency of collagen VI in Ullrich's disease. Furthermore, we found an abnormality of cell adhesion and abnormal regeneration or maturation in Ullrich's disease. Mutations in the genes COL6A1, COL6A2, COL6A3 are associated with Ullrich's disease and Bethlem myopathy. Bethlem myopathy is inherited in an autosomal dominant manner and Ullrich's disease usually in an autosomal recessive manner. Recently, de novo dominant mutations are reported in Ullrich's disease. We evaluated the role of nonsense-mediated mRNA decay (NMD) in Ullrich's disease that has a frameshift mutation with a premature termination codon in the COL6A2 gene causing the loss of collagen VI. The pharmacological block of NMD caused upregulation of the mutant collagen VI and partially functional extracellular matrix formation. Our results suggest that NMD inhibitors can be used as a therapeutic tool to rescue some human genetic diseases exacerbated by NMD.