Preimplantation genetic diagnosis of a large pericentric inversion of chromosome 5.

We report the first established pregnancy using preimplantation genetic diagnosis in order to avoid chromosomal imbalance in the progeny of a woman carrying a large inversion of chromosome 5. This is also the first time where it has been possible to study the distribution of balanced and unbalanced gametes in a female inversion carrier. In total, 23 embryos were biopsied in two separate treatments and analysed by fluorescent in-situ hybridization. Of these, 10 were unbalanced, nine were balanced and for four the analysis was inconclusive. The diagnostic procedure was performed within 3.5 h. This allowed the biopsied embryos to be transferred the same day as the biopsy was taken (day 3). Two embryos were transferred each time, and in the second treatment a twin pregnancy with two chromosomally balanced fetuses was established. Healthy twins were delivered at 34 weeks of gestation.