Spinal muscular atrophy (SMA) is a relatively common recessive autosomal disease affecting 1 in 6000 births. Four clinical types of the disease, types I - IV, are defined by decreasing severity of symptoms. SMA type 1 (Werdnig-Hoffman syndrome) strikes within the first 6 months of life, type II within 18 months, type III (Kugelberg-Welander) between 18 months and 18 years, and type IV has an adult onset. A loss of motor nerves in the spinal cord results in an atrophy of voluntary muscles leading to paralysis of the limbs and trunk which progresses, eventually resulting in death. In congenital cases, SMA can resemble congenital myotonic dystrophy (DM). SMA is an autosomal recessive disease. The loss of exons 7 of the Survival Motor Neuron (SMN) gene (chromosome 5q13.1), or pseudogene conversion, is responsible for 97% of the children affected with SMA type I. Patients with SMA types II, III, and IV also show the deletion of exon 7, but at a slightly lower incidence. In severely affected babies,  SMA analysis can be included in a Newborn Hypotonia Panel with myotonic dystrophy (DM) and Prader-Willi Syndrome (PWS) to expedite diagnosis.

• Confirmation of the diagnosis of SMA.
• Individuals at risk who wish prenatal diagnosis.
• Testing may be combined with testing for SMA and PWS in a Newborn Hypotonia Panel.

• PCR amplification of affected region, followed by restriction enzyme digestion to detect the deletion of SMN exon 7. **this assay cannot detect SMA carrier status**

SPECIMEN REQUIREMENTS:

• Blood EDTA (purple top) tubes:  

            Newborn: minimum 1-2 mL          

            Child/Adult: prefer 2 tubes of 3-5 mL

• Prenatal testing: Please contact the laboratory for instructions.

TURNAROUND TIME: 8 Days

CPT CODES: