Spinal muscular atrophy, also known as SMA, is an autosomal recessive disease characterized by degeneration of spinal cord motor neurons that leads to atrophy of skeletal muscle and overall weakness. The onset of weakness ranges from before birth to adulthood. The weakness is symmetric, proximal > distal, and progressive. SMA affects approximately 1 in 11,000 births in the U.S., and about 1 in every 50 Americans is a genetic carrier. SMA can affect any race or gender.
The genetics of spinal muscular atrophy are complex. PerkinElmer Genomics offers a wide range of SMA test options to cover all potential clinical needs.
- Newborn Screening:
- Our StepOne® test includes RT-PCR to detect the homozygous SMN1 exon 7 deletion present in 95% of patients with SMA.
- Second Tier testing using MLPA is available to determine SMN2 copy number for positive newborn screening results (SMN1=0).
- SMA Diagnostic Test
- The SMA diagnostic test should be used for individuals with suspected SMA and/or SMA-related phenotypes. This test can also be used to confirm a positive SMA screening assay.
- SMA Carrier Screening
- This test is appropriate for reproductive screening for individuals with a family history of SMA.
- Strong SMA phenotype with no SMN1 homozygous deletion
- For patients with a phenotype highly suspicious of SMA but do not have an SMN1 homozygous deletion, we offer LR-PCR to amplify the unique SMN1 sequence followed by sequencing to identify the potential sequencing variants which contribute to SMA (present in ~5% of the SMA patient population).
- Blended neuromuscular disorder phenotype
- Whole exome and whole genome sequencing are available testing options for patients with a blended phenotype.
- PerkinElmer Genomics’ whole genome sequencing assay includes SMA and Short Tandem Repeat (STR) screening of genes associated with neuromuscular disorders.