Increased IVF pregnancy rates after microarray preimplantation genetic diagnosis due to parental translocations

Abstract

We successfully performed preimplantation genetic diagnosis (PGD) and simultaneous preimplantation genetic screening (PGS) using single nucleotide polymorphism (SNP) microarrays for couples with balanced chromosome rearrangements in China. A total of 428 molecular karyotypes were diagnosed from 62 couples undergoing 68 in vitro fertilization (IVF) cycles. Of these, 48.1% of the embryos were chromosomally normal without translocation errors or aneuploidy. Of the 428 total embryos, 18.0% embryos were euploid, but were imbalanced due to the transmission of single translocation chromosome derivatives. A total of 6.5% of the embryos had chromosome abnormalities involving the parental chromosome aberration and other chromosomes aneuploidies. Significantly, 27.4% of the embryos were normal/balanced for the rearranged chromosomes, but were abnormal due to aneuploidy affecting other chromosomes. When evaluated on a per IVF cycle basis, 84% of the cycles had at least one chromosomally normal embryo available for uterine transfer. The clinical pregnancy rate per IVF cycle was 54%. Diagnosing genomically balanced embryos through 24 chromosome SNP microarray PGD/PGS, rather than minimally targeted fluorescence in situ hybridization (FISH), is a promising strategy to maximize the pregnancy potential of patients with known parental chromosomal translocations. Moreover, this is the first study to report the clinical application of SNP arrays to screen all 24 chromosome pairs of blastomeres and trophectoderm cells from patients carrying reciprocal translocations in China.