What types of genetic conditions can be detected by PGD?
(1) PGD for Chromosomal Abnormalities Abnormalities in the number or structure of chromosomes may occur at various stages of embryonic development (during the formation of the egg or sperm cells, the fertilization process, or the early cell divisions), all of which can give rise to abnormalities in the individual. Having an extra or missing chromosome(s) (described as aneuploidy) or pieces of chromosomes (unbalanced rearrangements) can result in arrest of embryonic development and failure of implantation and pregnancy, as well as miscarriage and the birth of an abnormal baby (e.g. Down’s syndrome). (See table 1) As women age, their eggs become more susceptible to chromosomal defects and aneuploidy rates increase. Thus, the chance of conceiving a chromosomally abnormal baby increases. Because PGD for aneuploidy determines the presence or absence of selected chromosomes, it can be used to determine the gender of the embryo (XY indicates male, XX indicates female) and to screen embryos fo
