PMID: 12370603
Issn Print: 0009-9201
Publication Date: 2002/09/01
Preimplantation Genetic Diagnosis
THE-HUNG BUI; JOYCE C. HARPER
Excerpt
Preimplantation genetic diagnosis (PGD) is an alternative to more conventional prenatal diagnosis by chorionic villus sampling or amniocentesis for patients known to be at increased risk of transmitting a specific single gene disorder or chromosomal imbalance to their offspring. 1 The issue of pregnancy termination is avoided as genetic tests are performed before embryo transfer, generally on one or two cells biopsied at the cleavage stage from embryos obtained after in vitro fertilization (IVF), thus permitting the selection of unaffected embryos before a pregnancy has been established. More recently, PGD aneuploidy screening (PGD-AS) has been used at a few centers in an attempt to improve the pregnancy rates in infertile couples treated by IVF. 2–4 For this purpose genetic analysis of both the first and second polar body is performed, but such diagnosis is restricted to maternally inherited or derived genetic defects, as no information about the genetic contribution from the father is provided.
Although PGD appears to be an attractive solution for couples at high risk of transmitting genetic diseases, relatively few centers worldwide offer the procedure, and <2,000 cycles have been performed in over a decade. The main limitation of PGD remains the relatively low efficiency of IVF, with only 20–30% of couples achieving a pregnancy per IVF cycle and similar results obtained after PGD. This review focuses on issues regarding the current status of clinical PGD, the technical difficulties encountered, and the limitations of the procedure. It takes also a prospective view on new developments and ethical issues.
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