Preimplantation genetic diagnosis of inherited cancer: familial adenomatous polyposis coli.
Ao A., Wells D., Handyside AH., Winston RM., Delhanty JD.
PURPOSE: Our purpose was to achieve preimplantation genetic diagnosis (PGD) of the dominant cancer predisposition syndrome, familial adenomatous polyposis coli (FAPC), as an alternative to prenatal diagnosis. METHODS: The affected patient was superovulated and oocytes were retrieved and fertilized by intracytoplasmic sperm injection (ICSI). Two cells were biopsied from each embryo and the whole genome was amplified by primer extension preamplification (PEP). Nested PCR was then used to amplify two APC fragments: one including the APC mutation site and the other an informative intragenic polymorphism. Both were detected by simultaneous single-strand conformation polymorphism and heteroduplex analysis. RESULTS: Four normally fertilized embryos were biopsied on day 3 post ICSI, and two cells were successfully removed from each embryo. Following PEP the APC mutation was successfully amplified in 7 of 8 cells, and the polymorphism in 6 of 8 cells. The APC mutation was detected in three embryos. This result was confirmed by identification of the mutation associated polymorphism in two cases. A single embryo was diagnosed as homozygous normal for the mutation and the polymorphism in both cells sampled. This unaffected embryo was transferred to the mother, but no pregnancy resulted. CONCLUSIONS: We report here the first diagnosis of a cancer predisposition syndrome in human preimplantation embryos. Our results indicate that difficulties associated with single-cell PCR, allele-specific amplification failure in particular, need not prevent preimplantation diagnosis of diseases with a dominant mode of inheritance, provided appropriate strategies are applied.