Spinal muscular atrophy (SMA) is a leading genetic cause of infant death worldwide, alongside cystic fibrosis. The incidence of SMA is 1 in 5000–10,000 live births. The carrier frequency for SMA is 1:35–50 in most populations. Typical symptoms of SMA include, floppy or weak arms and legs, movement problem, twitching or shaking muscles, bond and join problems, swallowing problems, and breathing problems.

If both parents are carriers of an abnormal SMA gene, there is a chance that each parents will pass the abnormal gene on to their child. An individual with two abnormal SMA gene will be affected with the disease. With each pregnancy there is a 25% chance that the child will be neither a carrier nor affected with the disease.SMN2 has been used as a potential target for SMA treatment for many years. This is because, unlike SMN1, SMN2 is present in all people with SMA. If the production of SMN protein from SMN2 can be increased in SMA, it has the potential to reduce disease severity

Uses multiplex PCR and Capillary Electrophoresis to determine the copy numbers (e.g., 0, 1, 2, 3, ≧4copy numbers) of exon 7 of SMN1 gene, exon 8 of SMN1 gene, exon 7 of SMN2 gene, or exon 8 of SMN2 gene. The detection from DNA can be accomplished within 3 hours to determinate the copy numbers of SMN1 gene for patient diagnosis and carrier testing of SMA. The assay also can be used for SMN2 copy number determination in SMA patient as an aid in prognosis and for treatment eligibility