Effects of eight InDel variants in FHIT on milk traits in Xinjiang brown cattle

In our previous genome-wide association study (GWAS), we identified the fragile histidine triad diadenosine triphosphatase (FHIT) gene in Xinjiang brown cattle (XJBC) as a candidate gene associated with cattle productive traits, with potential application in mark-assisted selection (MAS) in cattle breeding. FHIT is a prototype of a class of tumor suppressor genes that contain genomic loci mapped to common fragile loci. Here, 388 healthy and unrelated XJBC were selected to identify insertion/deletion (InDel) variants in the bovine FHIT and assess their effects on milk traits. Eight of the thirteen InDel loci were found to be polymorphic in FHIT. The polymorphism information content of the eight loci ranged from 0.061 to 0.375. The correlation analysis showed that all the new InDel variants were significantly related to six different milk traits (p < 0.05). The following variants presented a significant relationship with productive traits: P2-23bp with the 305 milk yield (p = 0.005) in the sixth parity; P3-24bp with the milk fat yield (p = 0.009) in the third parity; P5-21bp with the somatic cell score (p = 0.001) in the first parity and with the milk protein percentage (p = 0.002) in the sixth parity; and P7-26bp with the somatic cell score (p = 0.003) in the sixth parity. These findings will help evaluate InDel genotypes, within and between cattle breeds and identify potential target loci to accelerate progress in MAS in cattle breeding.