The diagnosis can be suspected by findings on a muscle biopsy or when a doctor experienced in muscular dystrophy examines you.
A serum creatine kinase (CK) blood test may also show raised levels which indicate a problem in the muscles. The muscle biopsy usually shows a deficiency of the involved proteins and can be helpful to identify the specific gene responsible of the symptoms.
The diagnosis has to be confirmed by identifying the mutated gene (α-SG, β-SG-, δ-SG-, γ-SG gene) which is done on a DNA sample from a blood test. Sarcoglycan genes are large genes and sometimes genetic analysis of all four genes is necessary, so testing is very lengthy and results may not be available for many months.