Association analysis of polymorphism in KiSS1 gene with reproductive traits in goats

- We evaluate the genetic variability in the KiSS1 gene of dairy goats.
- The T/A SNP is associated significantly with litter size.
- KiSS1 gene may be associated with Estradiol17β and progesterone profiles.

Understanding the genetic information of related genes is helpful for the selection and breeding course through marker assisted selection. The aim of the current study was to detect polymorphisms of the KiSS1 gene in 137 animals, including Baladi, Zaraibi and Damascus goat breeds by PCR-RFLP, and DNA sequencing and to investigate the association between these variants and reproductive traits. Comparison of the nucleotide sequence indicated the substitution of T with A at position 121 (T121A) in the intron 1 of the KiSS1 gene in all goat breeds. This substitution distorts the restriction site of the XmnI restriction enzyme and consequently two genotypes were detected (TA and TT). The T121A SNP is associated significantly with litter size in Damascus and Zaribi breeds (p = 0.025 and 0.001, respectively). The animals with the TT genotype in Damascus and Zaribi breeds had a significantly higher estradiol17β level than that recorded in TA genotype at estrus phase (p = 0.013 and 0.028, respectively) and late-luteal phase (p = 0.067 and 0.041, respectively) of the estrus cycle. Furthermore, animals with the TT genotype in Damascus and Zaribi breeds had significant higher progesterone level at mid-luteal (p = 0.037 and 0.045, respectively) phase. Meanwhile, there were no significant differences in progesterone level in late-luteal phase between both genotypes in Zaribi breed (p = 0.267). The current trial indicated that the prolific TT genotype in both Damascus and Zaribi breeds had superior estradiol17β level at estrus phase and an eminent progesterone level at both early and mid-luteal phases of the estrous cycle.