What Are The Disadvantages and Limitations of PGD for Aneuploidy?
Clinical misdiagnosis, which is the occurrence of a fetus or baby with chromosome abnormalities after PGD, is a risk. Analytical errors may arise from a problem with fixation of the cell nucleus, or a problem with the FISH procedure (e.g. failure of the probes to label the chromosomes, or incorrect interpretation of the fluorescent signals caused by overlapping, split or lost signals). Another pitfall associated with PGD is a condition called mosaicism in which chromosome anomalies are present in a cell yet not in other cells of that embryo (i.e. cells are chromosomally different within a single embryo). Mosaicism is common in human embryos generated in vitro and contributes significantly to the PGD error rate. Mosaic embryos can develop to blastocysts in culture, however there is a tendency for these embryos to arrest development, particularly if the mosaicism is extensive and chaotic (that is, different cells have different aneuploidies). Mosaicism may be patient-specific, i.e. some
