SMN1 Gene, Full Gene Analysis, Varies
Use
This test is useful for confirming a diagnosis of spinal muscular atrophy (SMA) by detecting nucleotide variants in the SMN1 gene. It plays a critical role in confirming the diagnosis in symptomatic individuals and aids in reproductive decision-making by serving as a second-tier carrier screening, particularly in situations where there is a family history of SMA but an affected individual is unavailable for testing. The test can also be used to screen the reproductive partner of a known SMA carrier to assess the risk of passing on the disease to offspring.
Special Instructions
The test involves full gene sequencing of the SMN1 gene using Polymerase Chain Reaction (PCR) followed by DNA sequencing. Reflex testing and additional charges may apply depending on the specimen type, such as fibroblast culture for skin biopsies. In the case of cord blood specimens, if maternal blood accompanies the sample, additional maternal cell contamination studies will be performed with an extra charge.
Limitations
While the SMN1 full gene analysis is effective in confirming the presence of deleterious nucleotide variants that cause SMA, it may not detect all possible pathogenic variants due to limitations inherent in sequencing technology. Rare variants outside the region typically sequenced or novel variant types not accounted for in the standard analysis may be missed. Additionally, the test may not differentiate between SMN1 and the homologous gene SMN2 in certain analyses, and it does not cover other potential genetic factors that could modify disease onset or progression.
New York Approved
Methodology
PCR-based (PCR)
Biomarkers
Result Turnaround Time
Not provided.
Related Documents
For more information, please review the documents below
Specimen
Other
Volume
Not provided
Minimum Volume
Not provided
Collection Instructions
For skin biopsy or cultured fibroblast specimens, fibroblast culture testing will be performed. Cord blood specimens may require accompanying maternal blood specimens for maternal cell contamination studies.