Which method in NIPS can detect triploidy?

The SNP method is well-suited for detecting triploidy in non-invasive prenatal screening (NIPS) because it utilizes single nucleotide polymorphism data to differentiate between maternal and fetal genetic material. In this method, the presence of three copies of specific chromosomal regions indicates triploidy, as the normal fetal genome would have only two copies.

SNP-based analysis allows for a more nuanced interpretation of the data, since it can discern the differences in allele frequency between maternal and fetal DNA. This is especially important when assessing conditions like triploidy, as it provides clarity on whether there are deviations in chromosome number that would not be easily identified through other methods.

Other methods, while useful in various contexts, do not have the same sensitivity and specificity for identifying triploidy. For instance, counting methods typically rely on whole chromosome counts which may miss the subtleties necessary to diagnose triploidy accurately. Fetal fraction analysis focuses primarily on the proportion of fetal DNA present in the sample rather than chromosomal abnormalities. Cell-free fetal DNA analysis offers general insights into fetal genetic conditions but may not precisely distinguish triploidy. Therefore, the SNP method stands out as the most effective approach for this specific condition.