To the Editor Dr Bianchi and colleagues1 described the incidental detection of occult maternal malignancies with noninvasive prenatal testing (NIPT). The authors evaluated 8 pregnant women who received an abnormal NIPT result discordant with the actual fetal genotype.
Five of these women received an NIPT result with at least a monosomy for chromosome 18, and 1 received a result suggestive for monosomies of chromosomes 13, 18, and 21. For routine NIPT, the authors used whole-genome massively parallel sequencing with targeted analysis (Illumina). Overrepresentation or underrepresentation of chromosomes 13, 18, 21, X, and Y was evaluated by “…constructing a ratio between the normalized coverage on each chromosome of interest and the sum of normalized coverage on a respective set of reference chromosomes…,”1 with the number of reference chromosomes typically being between 2 and 6 per target chromosome.
Sistermans E, Straver R, Faas BHW. Maternal Malignancies Detected With Noninvasive Prenatal Testing. JAMA. 2015;314(20):2192. doi:10.1001/jama.2015.12922