An Exploratory Study of Skeletal Muscle Abnormalities in Patients With Mutations in Alpha-Tropomyosin and PABP2 Genes

Mutations of the fast alpha-tropomyosin gene cause hypertrophic cardiomyopathy (HCM), and are also expressed in skeletal muscle. However, the skeletal phenotype is undetermined. We have identified three families in which HCM is caused by an alpha-tropomyosin mutation. Several family members of one of these kindreds have also inherited a distinct skeletal myopathy called oculopharyngeal muscular dystrophy (OPMD) which is caused by mutations of the poly(A) binding protein-2 gene (PABP2). The pathologic hallmark of this disease is unique nuclear filament inclusions in skeletal muscle fibers. It is possible that the skeletal muscle phenotype is more severe when the two diseases occur in the same patient. We wish to perform skeletal muscle biopsies to determine the skeletal myopathy in patients with alpha-tropomyosin, in patients with PABP2 gene mutation, and in patients who have inherited both diseases.