Genetic Polymorphism Of beta-lactoglobulin In Kenyan Small East African Goat (Capra Hircus) Breed Using PCR_RFLP And Sequencing

Abstract

Polymorphism in the beta-lactoglobulin gene has been successfully studied in many goat populations of the world. However, this has not been clarified yet in the local Kenyan goat (Capra hircus) breeds. The objectives of this study were to screen beta-lactoglobulin gene (BLG) variants and to identify its polymorphism in the Small East African goat breed using PCRRFLP and sequencing techniques. Vacuutainer tubes containing EDTA as an anticoagulant were used to collect blood from the jugular vein of a total of 60 animals sampled, 30 from each region (Samburu and Narok). Genomic DNA was then isolated using Qiagen QiAmp blood mini kit. The amplified products were observed as 426 bp length of exon 7 and the restriction digestion with SacII revealed two alleles, namely A and B and three genotypes, (AA, AB and BB) at the β- LG locus according to the restriction pattern. Allelic frequencies for goats found in Samburu and Narok were 0.233 and 0.133 respectively for A allele; 0.767 and 0.867 respectively for B allele, while genotypic frequencies were 0.1 and 0 for AA, 0.267 and 0.267 for AB, and 0.633 and 0.733 for BB respectively. In the pooled data for the Small East African goat breed, the allelic frequencies were 0.183 and 0.817 for the A and B allele respectively, while genotypic frequencies were 0.05, 0.267 and 0.683 for the AA, AB and BB respectively. No deviations from the Hardy Weinberg equilibrium were observed as earlier hypothesized. After PCR, a 426 base pairs sequence in exon 7 of 60 goat samples were sequenced and variation analyzed. Two point mutations corresponding to base substitutions were identified. The substitutions of G to A were found at both positions 6705 and 6751 as compared to the C. hircus sequence (Accession number Z33881.1). Analysis of Molecular Variance (AMOVA) revealed higher variation within populations (98.15%) than among populations (1.85%) and FST (0.01846). Further studies on other LGB regions are necessary to establish associations of all its mutations and the effects of the variants to milk production traits.