SGCD and sarcoglycanopathy: Sarcoglycanopathies (R3-R6) are caused by missense mutations of SGCA, SGCB, SGCG, and SGCD genes, that result in misfolding of the four corresponding sarcoglycan protein subunits that form the sarcoglycan complex in the sarcolemma of muscle cells (Fig. 1) [15].