Spinal Muscular Atrophy (SMA)

Whole blood or PurFlock buccal swab kit or Oragene Dx 500 saliva kit

8.5 mL whole blood or PurFlock buccal swab kit or Oragene Dx saliva kit

3 mL whole blood or PurFlock buccal swab kit or Oragene Dx saliva kit

Yellow-top (ACD-A) tube or lavender-top (EDTA) tube or PurFlock buccal swab kit or Oragene Dx 500 saliva collection kit

Whole blood: 4 days at room temperature or 4°C

Buccal: 60 days at room temperature

Saliva: 60 days at room temperature

This test is used for carrier screening for spinal muscular atrophy and diagnostic testing for individuals suspected of having spinal muscular atrophy.

Technologies used do not detect germline mosaicism and do not rule out the presence of large chromosomal aberrations including rearrangements and gene fusions, or variants in regions or genes not included in this test, or possible inter/intragenic interactions between variants or repeat expansions.

Variant classification and/or interpretation may change over time if more information becomes available. False positive or false negative results may occur for reasons that include: rare genetic variants, sex chromosome abnormalities, pseudogene interference, blood transfusions, bone marrow transplantation, somatic or tissue-specific mosaicism, mislabeled samples or erroneous representation of family relationships.

This test was developed and its performance characteristics determined by Labcorp. It has not been cleared or approved by the Food and Drug Administration.

Copy number assessment of SMN1 exon 7 by quantitative polymerase chain reaction (qPCR); reflex testing to SMN2 copy number analysis is performed for individuals with 0 copies of SMN1. For carrier screening, when two copies of SMN1 are detected, allelic discrimination qPCR targeting c.*3+80T>G in SMN1 is performed. The presence or absence of c.*3+80T>G correlates with an increased or decreased risk, respectively, of being a silent carrier (2+0).