Sgcb, encoding β -sarcoglycan, is one of the genes in the sarcoglycan family. The proteins encoded by Sgca, Sgcb, Sgcg, and Sgcd form part of the dystrophin-glycoprotein complex (DGC) in the muscle sarcolemma. The DGC acts as a linker between the muscle fiber cytoskeleton and the extracellular matrix, providing mechanical support during myofiber contraction [1].

Mutations in Sgcb cause limb-girdle muscular dystrophy type R4/2E. A study performed deep mutational scanning of Sgcb and found that variant functional scores were bimodally distributed and could predict pathogenicity of known variants, with less severe scores related to slower disease progression [2]. Another study developed a gene therapy based on adeno-associated virus for limb-girdle muscular dystrophy 2E/R4 caused by Sgcb mutations. Interim results showed robust Sgcb expression and preliminary motor improvements [3].

In conclusion, Sgcb is crucial for maintaining the integrity of the muscle sarcolemma through its role in the DGC. Research on Sgcb-related limb-girdle muscular dystrophy has led to the development of potential gene therapies, highlighting the importance of understanding Sgcb function for treating this disease [1,2,3].