352 Awardee Talk: Identification of novel haplotypes with recessive and allelic inheritance patterns affecting embryonic development processes, gestation losses and post-natal lethality in cattle

Abstract

Abstract Genomic data allows the screening of homozygous haplotypes and recessive lethal alleles, which could affect reproductive performance in cattle and other species. Here, we propose an approach based on tracing the inheritance of alleles from heterozygous parents to offspring to identify significant departure from the expected Mendelian inheritance (Transmission Ratio Distortion – TRD). TRDscan software was used to identify genomic regions with TRD using 436,651 trios (sire-dam-offspring) of genotypes from Holstein dairy cattle. SNP-by-SNP analysis was performed using 132,990 SNPs. TRD haplotypes were identified using sliding windows of 2-,4-,7-,10- and 20-SNPs. In total, 109 SNPs and 495 haplotypes were identified with significant TRD (Bayes factor≥100). Interestingly, some of the identified TRD regions overlap with previously known regions with recessive lethal alleles (e.g., HH0, HH1, HH3, HH5). Novel genomic regions with significant TRD were also identified with annotated genes functionally clustered into specific phenotypes related to male and female infertility and postnatal lethality. Approximately 18% of previously identified quantitative trait loci mapped around the TRD regions were related with fertility traits (calving ease, scrotal circumference, fertility index, and non-return rate). Validation of the results was performed using ~13,000 of Holstein embryo genotypes, in trios. The results will be integrated with the TRD regions identified to fine mapping the contribution of the TRD for each embryonic stage and they may be helpful to precisely target genomic regions associated with fertility, embryonic development processes, gestation losses and post-natal lethality in cattle.