This paper reviews the current status of preimplantation genetic diagnosis
(PGD), outlining the methods currently in use for the diagnosis of sex and
single-gem defects. New approaches under development are described, e.g. fl
uorescent polymerase chain reaction (PCR), the use of sub-telomeric probes
for patients with balanced reciprocal translocations, the analysis of first
and second polar bodies, the use of lasers to facilitate the biopsy of emb
ryos, and ways forward for infertile patients.