Genome-wide association studies for the concentrations of insulin, triiodothyronine, and thyroxine in Chinese Holstein cattle.

To further understand the genetic structure that is associated with insulin (INS) and thyroid hormones (TH), including triiodothyronine (T) and thyroxine (T), in Chinese Holstein cows, we conducted a genome-wide association study (GWAS) of thyroid hormones and insulin in cows. We conducted GWAS analysis on 1217 Chinese Holstein cows raised in southern China and found 19 significant single nucleotide polymorphisms (SNPs) in this study: 10 SNPs were associated with INS, 5 SNPs were associated with T, and 4 SNPs were associated with T. In our study, the GWAS method was used for preliminary screening on related genes of traits, and due to insufficient relevant literature, a functional analysis of genes could only be based on human studies. We observed that DGKB from Bos taurus chromosome (BTA)4 is strongly associated with insulin secretion. We found that EXOC4 gene was significantly correlated with T and T traits. Another significant SNP was located in the CYP7A1 gene, which has been confirmed to be affected by thyroid hormones.