Spinal Muscular Atrophy, SMN1 Carrier Testing
Label Mnemonic: SMACT
Epic Lab Code: LAB4075
Downtime Form: A-1a Miscellaneous Request
Commercial Mail-out Laboratory
5231 RCP
356-8593
Specimen(s):
Whole Blood
Collection Medium:
Pink top tube 6 mL (K2-EDTA)
Minimum:
Adult Minimum: 6 mL whole blood
Pediatric Minimum: 2-3 mL whole blood
Testing Schedule:
Test available Monday through Thursday as lab does not accept samples on Saturday. Consent form should be completed.
Turn Around Time:
14 days upon receipt at reference laboratory
Interpretive Data:
The survival motor neuron 1 (SMN1) gene has been shown to be homozygously deleted in approximately 95% of the SMA patients (0 SMN1 copy). The majority of the other 5% of affected patients are compound heterozygotes, possessing a single SMN1 deletion (1 SMN1 copy) and a smaller intragenic type of mutation within the SMN1 gene. Loss of SMN1 is essential to the pathogenesis of the disease, while the disease severity is primarily correlated with the number of copies of SMN2. Most type 1 patients have two copies of SMN2(and occasionally one copy). Three copies are common in SMA type II patients, and type III patients often have 3 or 4 copies of SMN2.
CPT Code:
81401