Please note that the website is being retired as of May 31, 2019. Please revise your bookmarks to use the Quest Test Directory for your inquiries:

Welcome to the new Quest Diagnostics Test Directory

Search with confidence for the right test! Use our helpful education resources, and tools to narrow your search by specialty and test category, and compare tests side-by-side.
Test Menu
Test Change Details
Allergy & Immunology
Cardiology & Coagulation
Infectious Disease
Women's Health
18041: Sma Carrier Screen Print View
Technical Results      

1 Whole Blood EDTA 4 (2) mL   Refrigerated - 14 Day(s)/Room Temperature - 8 Day(s)  
  CVS Cultured cells T25   Room Temperature - 48 Hour(s)  
  Whole Blood ACD Sol B 4 (2) mL   Refrigerated - 14 Day(s)/Room Temperature - 8 Day(s)  
  Amniotic Fl Cultured T25   Room Temperature - 48 Hour(s)  
  Amniotic Fluid   Room Temperature - 48 Hour(s)  
  Whole Blood ACD Sol A 4 (2) mL   Refrigerated - 14 Day(s)/Room Temperature - 8 Day(s)  

Spinal Muscular Atrophy (SMA) is one of the most common autosomal recessive diseases. SMA is characterized by the degeneration of the anterior horn cells of the spinal cord which leads to symmetric proximal muscle weakness. The estimated incidence of SMA is 1/6,000 to 1/10,000 live births with a carrier frequency of 1/40 to 1/60. Clinical presentation of SMA, mainly based upon age of onset of symptoms, is classified into four SMA subtypes: subtype I - onset before six months of age, subtype II - onset between six and 12 months of age, subtype III - onset in childhood after 12 months of age, and subtype IV - adult onset. Each subtype displays significant variance of clinical prognosis, including lifespan. The survival motor neuron 1 (SMN1) gene has been shown to be responsible for 99% of SMA cases. An adjacent homologous gene, SMN2, encodes a protein identical to that of SMA1. SMA is caused by a critical reduction in the total amount of functional SMN protein. Typically 80-90% of SMN protein is derived from functional SMN1 genes, while 10-20% is derived from SMN2 genes. Therefore, SMN protein expression, or dosage, is based largely upon SMN1 gene copy number, and to a much lesser extent, SMN2 gene copy number. Loss of functional production of SMN protein most commonly occurs by deletion of SMN1 and/or SMN2 genes, either by homologous recombination or gene conversion (95% of SMA alleles). The remaining 5% of SMA alleles harbor point mutations in the SMN1 gene(s) that effectively eliminates the production of functional SMN protein from those gene copies. Although a diagnosis of SMA depends upon SMN1 gene copy number, a less severe SMA phenotype may be associated with an increased number (>=3 copies) of functional SMN2 gene copies. Conversely, a severe SMA phenotype may be associated with fewer (<=2) functional SMN2 gene copies.

Whole blood: Normal phlebotomy procedure. Store and ship ambient
immediately. Do not freeze.
Setup Schedule

Reported (Analytical Time)
3 days

CPT Code

The CPT codes provided are based on AMA guidelines and are for informational purposes only. CPT coding is the sole responsibility of the billing party. Please direct any questions regarding coding to the payer being billed.

Reject Criteria:
Samples received frozen; Clotted specimen
Transport Temperature:
Room temperature Send specimen to testing lab for viability determination. Do not reject.
Allele Specific Real-Time Polymerase Chain Reaction, ddCt Method

1996 - 2019 Quest Diagnostics Nichols Institute of Valencia
For test information, please call Client Services at 800-421-4449.

San Francisco Web Design & Database