Gene SGCB
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Also known as
Sarcoglycan Beta, A3b, LGMD2E, LGMDR4Overview
SGCB (Sarcoglycan Beta) encodes the beta subunit of the sarcoglycan complex, which is an integral component of the dystrophin-glycoprotein complex (DGC) in skeletal and cardiac muscle. Like its partner subunits (alpha, gamma, and delta sarcoglycans), the beta sarcoglycan protein spans the muscle cell membrane and helps form a protective complex that stabilizes the sarcolemma during muscle contraction. This complex creates a critical structural bridge between the intracellular cytoskeleton and the extracellular matrix, preventing muscle membrane damage during the mechanical stress of repeated muscle contractions.Mutations in SGCB cause limb-girdle muscular dystrophy type 2E (LGMD2E), also known as LGMDR4, an autosomal recessive muscular dystrophy that primarily affects the proximal muscles of the limbs. The condition typically manifests in childhood or early adolescence with progressive weakness in the shoulder and pelvic girdle muscles, leading to difficulty with activities such as climbing stairs, lifting arms overhead, and rising from a sitting position. The severity and rate of progression can vary considerably between individuals. Many patients develop elevated serum creatine kinase levels and may experience cardiomyopathy and respiratory insufficiency as the disease advances. Genetic testing for SGCB mutations is important for accurate diagnosis, appropriate clinical monitoring including cardiac assessment, and family planning.