ABSTRACT
INTRODUCTION For couples at risk of transmitting a genetic disease, preimplantation genetic diagnosis (PGD) and transfer of disease-free embryos oer alternatives to prenatal diagnosis by chorionic villous sampling or amniocentesis, followed by therapeutic abortion of aected fetuses. Molecular PGD was initially employed for embryo sexing in couples at risk for X-linked diseases. e technique used polymerase chain reaction (PCR) to amplify Y chromosome-specic sequences, and only embryos diagnosed as females were transferred (1). During the last two decades, the range of genetic abnormalities that can be detected by PGD has increased exponentially and in fact it may be performed for virtually any genetic disorder for which the mutation has been detected. PGD can also be employed in carriers of cancer predisposition genes and other late-onset genetic conditions. is, however, raises many ethical and practical questions. For instance, familial adenomatous polyposis (FAP) is an autosomal dominant syndrome with almost 100% risk of colorectal cancer without prophylactic colectomy. In a study including 20 individuals with FAP, 95% would consider undergoing prenatal testing and 90% would consider PGD (2). In comparison, carriers of BRCA1 or BRCA2 mutations are at risk for breast and/or ovarian cancer, but at a comparatively lower risk of developing malignancy. A similar survey conducted among such carriers revealed that 75% felt it was acceptable to oer PGD for this indication, but only 14% of patients contemplating a future pregnancy would consider PGD themselves (3).
