Detection of aneuploidy and chromosomal mosaicism
in human embryos during preimplantation sex determination by fluorescent in situ hybridisation (FISH).
, in which only some cells show a particular abnormality, may or may not be more readily detected by array-CGH than by standard techniques.
5 percent of embryos may be implanted with undetected genetic disorders because of a rare condition called chromosomal mosaicism
There could be some reasons for lack of demonstration of chromosomal mosaicism
in all individuals with HI: (1) most cytogenetic studies have been directed so far at peripheral lymphocytes or at cultured fibroblasts obtained from skin biopsies rather than at cultured keratinocytes or melanocytes (lines of Blaschko are epidermal not dermal), and (2) some genetic mosaicisms are too subtle to be detected by current techniques.
The downside of using FISH is that it is applied at the blastomere stage, which does not represent the rest of the embryo and is susceptible to chromosomal mosaicism
in embryos during cell division, which can lead to the transfer of abnormal embryos.