How is sma diagnosed?

See below: (spinal muscular atrophy) defining signs and symptoms are the first clue. To confirm diagnosis, a genetic test is done. If that is negative but the physician still things SMA is the cause of the patient's symptoms, an electromyography, enzyme creatnine kinase, and nerve conduction studies can be done.

"Diagnosis based on: molecular genetic testing. Mutations in SMN1...cause SMA; increases in SMN2 copy number often modify the phenotype. SMN1...is the primary gene in which mutation causes SMA. About 95%-98%...are homozygous for a deletion or gene conversion of SMN1 to SMN2 and about 2%-5% are compound heterozygotes for an SMN1 deletion or conversion mutation and an SMN1 intragenic mutation." coninued