Brief Description

Spinal muscular atrophy (SMA) is a condition that affects the motor neurons of the spinal cord. Motor neurons are specialized nerve cells that control the muscles used for activities such as breathing, crawling, and walking. In people affected by SMA, the loss of motor neurons leads to progressive muscle weakness and atrophy (wasting). Without treatment, SMA can lead to death in early childhood.

SMA screening involves performing real-time quantitative polymerase chain reaction (qPCR), which allows us to measure the presence of the gene responsible for it, called SMN1. With this method, we are able to find small changes to this gene. Around 95% of individuals with SMA will have the changes we are looking to find. This test is only able to identify children with or without the disease and not those who may be carriers.

Quick Facts

Laboratory Unit


Real-Time PCR

Specimen Collection

Missouri newborn screening samples must only be collected on the Food and Drug Administration (FDA) approved blood collection forms that must be pre-purchased from the MSPHL. The optimum collection time is between 24 and 48 hours-of-age. The instructions for collecting the samples are listed on the back of the collection form. All 5 circles on the filter paper need to be filled with blood from one side and then air dried for at least 3 hours in a horizontal position without allowing the blood to touch any surface during drying, including other parts of the card (see image).
See "Rules for Collection".


Store the dried blood samples at room temperature in the envelopes provided by the State Public Health Laboratory and transport within 24 hours of collection

Acceptable Specimen Type(s)

Initial Screen (the red form) or Repeat Screen (the green form)

Test Request Form(s)

Included in kit

Possible Results

Normal: No action required.
High Risk:
 Results are in the high risk range. Final results are immediately sent to the Newborn Screening SMA coordinator. The SMA coordinator will contact the primary care provider immediately and provide instructions for follow up, along with the SMA results. It is important that the primary care provider follow the instructions and contact the pediatric neurologist for appropriate follow up testing and consultation.
No Results: Results for SMA were inconclusive. Send a repeat newborn screening specimen as soon as possible, preferably no later than 1 week.

All final results are sent to the submitter and physician of record/primary care provider.

Unacceptable Conditions

Interfering Substances

Follow the Missouri NICU guidelines.

Result Reported

1 to 3 working days after receipt of specimen


$95 charge - for full panel of screening disorders 

CPT Codes




Additional Information

Estimated prevalence is 1:10,000