Clinical and genetic characterization of limb girdle muscular dystrophy R7 telethonin-related patients from three unrelated Chinese families.

Limb girdle muscular dystrophy LGMD R7 telethonin-related is a rare autosomal recessive muscle disorder characterized by proximal muscle weakness of pelvic and shoulder girdles. Mutation in TCAP is responsible for LGMD R7, and the disease has a wide geographic distribution in diverse populations, but genotype-phenotype relationships remain unclear. We collected 5 LGMD R7 patients from three unrelated Chinese families. The average onset age was 16 ± 1.41; the initial symptoms included progressive proximal muscle weakness in limbs, difficulty in fast running, and asymmetric muscle atrophy in calves. Muscle MR imaging showed varying severity of fatty infiltration in the pelvic girdle, thigh, and calf muscles, and the severity of muscle infiltration was related to the length of the disease course. Muscle histopathology revealed aberrantly sized muscle fibers, internal nuclei, split fibers, rimmed vacuoles, monocyte invasion, and necrotic fibers. Sequencing identified one novel and one previously reported TCAP mutation. Our study extends the known distribution of this rare muscular dystrophy and presents the first detailed clinical and genetic characterizations of LGMD R7 cases from the Chinese population. Our work expands the mutation spectrum known for LGMD R7 and emphasizes the need for clinicians to consider TCAP mutations when evaluating patients with symptoms of limb girdle muscular dystrophy.