New mutations in DQA2 exon 2 and their associations with some production traits and serum parameters of sheep

The DQA2 gene is a member of class II major histocompatibility complex (MHC). The ovine class II MHC mediates specific immunological responses to exogenous antigens. Single strand conformational polymorphism (SSCP) and direct sequencing methods were used to detect polymorphism of DQA2 gene exon 2 in 322 Mehraban and Lori-Bakhtiari ewes. Nine combined genotypes and several nucleotide changes were identified in the studied fragment. Associations of the observed genotypes with body weight, milk contents, log of milk somatic cell count and some serum parameters were also investigated. The observed genotypes had significant associations (P < 0.05) with serum levels of α2-globulin, γ-globulin, total globulins and albumin, as well as milk protein and lactose levels. Some SNPs, detected between 45 and 240 bp of the studied fragment, had significant associations (P < 0.05) with the studied production traits and serum parameters. The results of the present study showed that the studied fragment of DQA2 exon 2 has a high polymorphism and heterozygosity and could be considered as an important marker for marker assisted selection.