Clinical genetics
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Pre-implantation genetic diagnosis (PGD) is generally defined as the testing of pre-implantation stage embryos or oocytes for genetic defects. It has been developed for couples whose potential offspring are at risk of severe Mendelian disorders, structural chromosome abnormalities or mitochondrial disorders. Pre-implantation embryo diagnosis requires in vitro fertilization, embryo biopsy and either using fluorescent in situ hybridization or polymerase chain reaction at the single cell level. ⋯ However, diagnosis from a single cell remains a technically challenging procedure, and the risk of misdiagnosis cannot be eliminated. An ethical discussion of the question of whether PGD is acceptable at all-the 'desirability question'-is a rearguard action. Discussion must primarily focus on the conditions of exercising due caution in and the dynamics of PGD.