What limitations does karyotype testing have?

Karyotype testing is a powerful tool used to examine an individual's chromosomes and detect chromosomal abnormalities. One of its limitations is the potential inability to identify mosaicism, particularly when the population of cells analyzed does not include the cells exhibiting the mosaic characteristics. Mosaicism occurs when some cells have a different genetic makeup from the rest, and if these atypical cells are not included in the sample collected for karyotyping, the test may not reflect the full genetic picture of the individual. This situation can lead to false reassurance, as the test may appear normal when, in fact, a proportion of cells may carry significant abnormalities that are clinically relevant.

Karyotype testing does have other limitations, such as not detecting smaller rearrangements or point mutations which are beyond the resolution of standard karyotyping. While karyotyping is an important diagnostic test, it is not exhaustive of all genetic disorders, as certain conditions may require more advanced techniques like high-resolution genomic analysis or specific mutation testing. Additionally, karyotype testing is not the only option available during pregnancy; other tests, such as non-invasive prenatal testing (NIPT) with cell-free fetal DNA or chorionic villus sampling (CVS), may also be utilized, depending on the clinical situation.