Abstract: Disclosed is a method for treating a patient suffering from the disease sarcoglycan-deficient limb-girdle muscular dystrophy by gene replacement therapy. Sarcoglycan gene replacement therapy produces extensive long-term expression of the sarcoglycan species which restores the entire sarcoglycan complex, results in the stable association of alph&agr;-dystroglycan with the sarcolemma, and eliminates the morphological markers of limb-girdle muscular dystrophy. In another aspect, the invention relates to a method for determining a specific defective sarcoglycan species in the tissue of a patient. The method involves culture of muscle cells obtained from the patient, and the independent introduction of expression vectors encoding each of the sarcoglycan species, &agr;, &bgr;, &ggr;, and &dgr;, into the cultured cells with subsequent assaying for restoration of the dystrophin-glycoprotein complex.