SGCB and cardiomyopathy: The T182A mutation in SGCB (c.544A>G) is associated with a Duchenne muscular dystrophy–like presentation and cardiomyopathy.41, 53 The rationale behind this experiment was to determine whether ER retention of the β‐sarcoglycan mutant would disrupt cell surface localization of the brain sarcoglycan complex in heterologous cells.