Preimplantation Genetic Diagnosis (PGD) involves the analysis of single cells (blastomeres) biopsed from embryos 3 days after fertilization, or of oocyte polar bodies removed before fertilization (1st PB) and at the zygote stage (2nd PB). The purpose of such tests is to determine which embryos generated using assisted reproductive techniques, are unaffected by a specific gene disorder or chromosomal abnormality. Embryos determined to be genetically normal for the genes/chromosomes assessed are then transferred to the uterine cavity of the female partner.

Portuguese type familial amyloidotic polyneuropathy (FAP type I) is an autosomal dominant disease presenting an inherited mutation in the gene encoding the plasma protein transthyretin (TTR). We have developed a fluorescent PCR method to detect TTR Met30 mutation at the single cell level. Twenty-three clinical cycles were performed in twelve couples. From the 263 methaphase II injected oocytes, 237 fertilized and 250 were analysed. A positive signal in the nested PCR reaction was obtained in 201 samples, corresponding to a DNA amplification efficiency of 80.4%. Here we review the Portuguese experience in Preimplantation Genetic Diagnosis for FAP type I.