Genetics: Preimplantation diagnosis of cystic fibrosis by simultaneous detection of the W1282X and δf508 mutations

W1282X (W) and ΔF508 (Δ) are the two most common mutations of the cystic fibrosis Israeli population. Patients who are homozygotes (WW and ΔΔ) as well as compound heterozygotes (WΔ) present a severe phenotype of the disease. In the present study, we have developed a polymerase chain reaction (PCR)-based method for the detection of both mutations simultaneously in a single blastomere. Unfertilized human oocytes and single polyspermic blastomeres were subjected to a two-round PCR amplification: a first round of multiplex PCR followed by a second round of nested PCR, done seperately at each locus. Clear signals at both loci were obtained in 51% (47/65) of oocytes and 69% (24/35) of blastomeres. The genotype of the single cell analysed was determined by endonuclease digestion of the W products and by heteroduplex formation of the ΔF products. This diagnostic system will allow the identification of affected embryos (WW, ΔΔ, WΔ) as well as phenotypically normal carriers (W++Δ), and therefore may be used for cystic fibrosis preimplantation diagnosis in families who carry either or both mutations.