Patients who have experienced a spontaneous pregnancy loss want to know the reason for their loss. CMA provides an improved alternative to conventional G-banded karyotype for families seeking answers.
Chromosomal microarray analysis (CMA) provides an improved alternative to standard G-banded karyotyping with the ability to detect submicroscopic genomic rearrangements, faster turnaround time and improved test success rate. The oligo-SNP CMA contains over 2.6 million probes used to detect copy number variations. Additionally, the array can also detect aneuploidy, microdeletions/microduplications and some forms of uniparental disomy across 23 chromosomes. The array also provides exon-level resolution in 130 select genes and associated regions of interest.
Comparison of Pregnancy Loss Testing Options
Detection of Maternal-Cell Contamination (MCC)
A major limiting factor in analyzing specimens from spontaneous pregnancy loss is maternal cell contamination (MCC), where the tissue studied is maternal in origin and not fetal. For example, if the fetal sample is a non-affected female, standard test methods like karyotype are unable to determine the sample origin, making the test inconclusive. With CMA, a sample of maternal DNA is first analyzed and compared to the spontaneous pregnancy loss sample, allowing for conclusive determination of whether the sample is fetal or maternal in origin. In the case of an egg donor pregnancy, the maternal sample should be submitted from the gestational carrier in order to rule out MCC.
No Cell Culture Required
While standard G-banded karyotype requires cell culture for analysis, which can take four weeks to complete, CMA uses extracted DNA. Using extracted DNA greatly decreases the turnaround time required for testing. Testing can also be performed on paraffin-preserved (FFPE) samples from a prior miscarriage. This can be especially beneficial to patients with recurrent pregnancy loss. FFPE samples are accepted on a case-by-case basis. Please contact Progenity’s genetic counselors at +1 855-293-2639, option 4, for approval and additional information.
While CMA is very accurate, not every genetic abnormality can be detected. The test is not designed to detect balanced reciprocal translocations, inversions, mosaic abnormalities less than 14%, point mutations or other changes at a single-gene level.