The effect of blastomere loss during frozen embryo transfer on the transcriptome of offspring's umbilical cord blood.

Blastomere loss is a common issue during frozen-thawed embryo transfer (FET). Our previous study showed that blastomere loss was associated with an increased risk of small-for-gestational-age (SGA) neonates. The present study assessed the impact of blastomere loss during cryopreservation by comparing the mRNA profiles of umbilical cord blood of FET offspring from the prospective cohort study. Umbilical cord blood samples were collected from 48 neonates, including 12 from the loss group, 11 from the intact group, and 25 from the matched spontaneous pregnancy group. RNA-seq technology was used to compare the global gene expression profiles of the lymphocytes. Then, we used TopHat software to map the reads and quantitative real-time PCR to validate some important differentially expressed genes (DEGs). We identified 92 DEGs between the loss group and the spontaneous pregnancy group, including IGF2 and H19. Ingenuity Pathway Analysis (IPA) showed that the DEGs were most affected in the blastomere loss group. Downstream analysis also predicted the activation of organismal death pathways. In conclusions, our pilot study sheds light on the mechanism underlying how human blastomere loss may affect offspring at the gene expression level. These conclusions are, however, only suggestive, as the current study is based on a very limited sample size and type or nature of biological samples. Additional studies with larger sample sizes and independent experiments with placental samples should be conducted to verify these findings.