This product uses human peripheral EDTA anticoagulant blood as the test specimen to detect the copy number of SMN1 at the 7th exon and (or) the 8th exon in human genomic DNA. Spinal muscular atrophy (SMA) is an autosomal recessive genetic disease characterized by degeneration of motor neurons in the anterior horn of the spinal cord, which is clinically manifested as progressive and symmetrical muscle weakness, atrophy and paralysis in the proximal extremity and trunk. The muscle atrophy is symmetrical, the lower limbs are more serious than the upper limbs, and the proximal part of the body is more susceptible to invasion. Due to the gradual degeneration of muscles, the patient will gradually lose normal physiological functions such as standing, crawling, swallowing, and even breathing, and severe cases will lead to death. The age of onset of this disease is possible from infant to adult, its incidence rate is 1/10000~1/6000, and the population carrying rate is 1/60~1/40.