Abstract

DUCATELLI, M.E et al. Preimplantational genetic diagnosis (PGDs) in carriers of balanced structural rearrangements by array comparative genomic hybridization (aCGH). BAG, J. basic appl. genet. [online]. 2016, vol.27, n.2, pp.17-24. ISSN 1852-6233.

Carriers of chromosomal rearrangements have an increased risk of producing aneuploid gametes, which originate abnormal embryos, most of them lethal. Only a minority of them complete the pregnancy, delivering malformed children with unbalanced chromosomes. The majority of Preimplantational Genetic Diagnosis (PGDs) reported in these carriers were detected in blastomere using FISH. The objective of this work was to determine the risk of chromosome misbalance in blastocysts. Herein, we report 26 couples with chromosome rearrangements: five with pericentric inversions, four with Robertsonian translocations and 17 with reciprocal translocations. Trophectoderm biopsies were performed on days five or six post Intracytoplasmic Sperm Injection (ICSI). The array Comparative Genomic Hybridization (aCGH) was done with 24 Sure Plus of BlueGnome-Illumina® and the blastocyst transfer in a deferred cycle. Average of aspired oocytes was 16.2 (r= 5-46), of normal fertilized oocytes was 11.1 (r= 2-26) and of obtained blastocysts was 4.8 (r= 1-11). In the reciprocal translocation group, 63 blastocysts were biopsied, 44.4 % of them was normal and 55.6 % abnormal. In the Robertsonian translocations group, 23 blastocysts were studied, 56.5 % of them was normal and 43.5 % abnormal. In the chromosomal inversions group, 25 blastocysts were analyzed, 52 % was normal and 44 % abnormal. We could not obtain any information for one blastocyst due to a failure in DNA amplification. The results allow us to conclude that the theoretical expected risk for structural chromosome rearrangements in trophectoderm biopsy is lower than in blastomeres and/or gametes. Since not all fertilized oocytes reach the blastocyst stage, the quantity of biopsied blastocysts is much lower than in blastomere biopsy, reducing thus the costs of the PGDs.

Keywords : Molecular karyotype; Preimplantation diagnosis; Throphectoderm biopsy.

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