Two distinct phenotypes and a novel mutation in limb-girdle muscular dystrophy R7 telethonin-related patients from Thai neuromuscular center.

Abstract

Limb-girdle muscular dystrophy R7 telethonin-related (LGMDR7) is a rare autosomal recessive disorder caused by TCAP gene mutations. This study described the phenotypic spectrum, genetic characteristics, and muscle magnetic resonance imaging (MRI) findings of patients with LGMDR7. Five patients from three unrelated families with TCAP mutations were retrospectively identified at the Neuromuscular Center at King Chulalongkorn Memorial Hospital. Demographic, clinical, laboratory, and muscle MRI data were collected and analyzed. We observed a mild phenotype associated with asymptomatic/paucisymptomatic hyperCKemia in one family and a classic limb-girdle muscular dystrophy phenotype in two unrelated patients. The novel deletion variant c.136_137del was identified in a compound heterozygous state with c.26_33dup in a family with a mild phenotype. Muscle MRI of four patients revealed consistent sparing of the sartorius muscle in all patients. This study expands the clinical and genetic spectrum of LGMDR7 by demonstrating an asymptomatic/paucisymptomatic hyperCKemia phenotype and identifying the novel c.136_137del variant. The muscle MRI findings highlight a characteristic pattern in which the sartorius muscle is consistently uninvolved. These findings contribute to a better understanding of the disease and assist in developing future diagnostic strategies for affected individuals, specifically by using clinical profiles in conjunction with the characteristics of muscle MRI.