Polymorphism studies of Prolactin Receptor (PRLR) gene in Indigenous Grey Cattle breeds of India

Alterations in candidate genes by way of substitutions, insertions, or deletions at restriction enzyme cleavage sites may produce changes in the resulting length of DNA fragments called restriction fragment length polymorphisms, which may serve as genetic markers if they are linked to quantitative trait loci. Recently, single nucleotide polymorphisms (SNPs) have gained high popularity as markers for genetic studies due to their high accuracy and reproducibility. The present study was undertaken to detect polymorphism in Exon 10 region of Prolactin Receptor (PRLR) gene. We have detected two novel SNPs in Exon 10 region of Prolactin Receptor (PRLR) gene in 10 indigenous grey cattle breeds from different agro-climatic regions of India. The PCR product using a set of primer pairs were digested with NaeI and SmlI restriction enzymes resulting in fragments of 232 bp and 168 bp from exon 10 region of PRLR gene. Out of 455 animals screened, 75.8% animals were homozygous AA, 3.1% of animal were homozygous CC and 21.1% animals were heterozygous (AC). The frequency of C allele was significantly lower than the A allele in all the cattle breeds studied. The mean gene frequency of C allele was estimated to be 0.136 with Kangayam showing the maximum frequency (0.213), and Punganur the minimum frequency (0.042). For the second set of primer out of 454 animals were screened, GT genotype was most frequent with genotypic frequency of 43.2%, followed by homozygous GG genotype with a frequency of 43.0% and TT with 13.8% frequency. The frequency distribution of G allele across the ten breeds ranged from 0.446 (Nagori) to 0.771 (Hill Cattle) with a mean value of 0.645, whereas that of T allele ranged from 0.229 (Hill Cattle) to 0.554 (Nagori) with a mean value of 0.355.