SMN1 Gene Full Mutation Analysis, Whole Blood, Targeted Sequencing

What This Test Looks At

The test analyzes the SMN1 (survival motor neuron 1) gene, which provides instructions for a protein that motor neurons need to function. Targeted sequencing reads the gene's genetic code to look for mutations, including the common exon 7 deletion as well as smaller changes such as point mutations.

Why Whole Blood Is Used

SMN1 testing is typically performed on whole blood because white blood cells contain a complete set of the body's DNA, including both copies of the SMN1 gene. A blood draw is a standard, low-risk way to obtain high-quality genetic material.

How the Test Is Performed

A healthcare professional collects a blood sample, which is sent to a genetics laboratory. There, DNA is extracted and the SMN1 gene is examined by targeted sequencing, comparing the patient's sequence against a reference to detect deletions, small insertions, or other sequence changes.

What Results Can Mean

Results can show whether zero, one, or two functional copies of SMN1 appear to be present and whether any sequence changes were detected. Because spinal muscular atrophy is inherited in an autosomal recessive pattern, results are interpreted together with a person's symptoms, family history, and sometimes testing of family members.