PGD in female carriers of balanced Robertsonian and reciprocal translocations by first polar body analysis

Preimplantation genetic diagnosis (PGD) using the first polar body (1PB) is a modality of PGD that can be used when the woman is the carrier of a gene tic disease or of a balanced chromosomal reorganization. PGD using 1PB biop sy in carriers of balanced chromosome reorganizations has not become genera lized. Here, we describe our experience based on the analysis of unfertiliz ed or fresh, non-inseminated control oocytes, by fixing separately the 1PB and the corresponding oocyte, and on the study of six clinical cases of PGD using 1PB biopsy (four Robertsonian translocations and two reciprocal tran slocations). In fresh oocytes, the chromosome morphology of the 1PB was wel l preserved, and the results were always concordant for each oocyte-1PB pai r. This indicates that the 1PB can be reliably used for the diagnosis of ch romosome reorganizations. In these studies the technical problems encounter ed when performing PGD using 1PB biopsies for chromosome studies are also a ddressed. Three different strategies of 1PB biopsy (laser beam, partial zon a dissection and acid Tyrode's) and two different protocols (intracytoplasm ic sperm injection before or after 1PB biopsy) and their effect on the perc entage of oocytes diagnosed and the fertilization rate, are discussed. In r eciprocal translocation cases, published in the literature or studied by us , in which at least nine oocytes had been diagnosed, a correlation has been found between the frequency of nondisjunction observed and the theoretical recombination rate. To date, PGD by 1PB analysis alone or combined with bl astomere biopsies in female carriers of chromosomal rearrangements has been used in 18 cases, with a further six cases reported here. A total of 325 c umulus-oocyte complexes have been obtained, of which 294 were biopsied and 224 were diagnosed. A total of 52 embryos was transferred, 19 of which impl anted and 17 produced full-term pregnancies.