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Basic Non-Invasive Prenatal Testing panels report on the three common autosomal trisomies: Trisomy 21 (Down syndrome), Trisomy 18 (Edwards syndrome), and Trisomy 13 (Patau syndrome) — along with sex chromosome aneuploidies such as Turner syndrome (45,X) and Klinefelter syndrome (47,XXY). Genome-wide panels additionally report aneuploidy status for the remaining chromosomes (rare autosomal aneuploidies) and larger copy number variants, typically at a size cut-off of 5 to 7 megabases, depending on the laboratory’s platform, type of testing and validated reporting thresholds. Key limitations to communicate to patients: it remains a screening test, not a diagnostic one, so any high-probability result requires confirmation via amniocentesis or chorionic villus sampling before a clinical decision is made; it does not detect structural birth defects, single-gene disorders, or triploidy reliably and its accuracy depends on adequate fetal fraction, which can be reduced in women with a higher body mass index, in very early gestation, or in certain maternal conditions. As more chromosomes are screened, the likelihood of results arising from confined placental mosaicism, maternal mosaicism, or a co-existing maternal malignancy also increases, which is a specific counseling point for genome-wide panels.
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