BACKGROUND: Major histocompatibility complex (MHC) is a group of genes which codes for binding of antigenic peptides and presenting them to T cells. MHC molecules polymorphism is associated with presenting different antigens, immune and autoimmune responses. One of the most important dog MHC genes is DRB1. The association between this gene and its alleles with Atopic Dermatitis has been reported. OBJECTIVES: In this study, the association between canine Atopic Dermatitis and DLA-DRB1 alleles has been evaluated using HRM (High Resolution Melting) genotyping method. METHODS: Blood samples were collected from 20 dogs with Atopic Dermatitis and 20 healthy dogs. Frequency of different DRB1 genotypes, as well as heterozygosity and homozygosity of alleles were analyzed using HRM. Their associations with Atopic Dermatitis were evaluated by statistical analysis. RESULTS: Based on the HRM analysis, genotypes were grouped in 9 types (A-I). Statistical analysis showed that the presence of type D allele in the exon II of DLA-DRB1 gene increases the risk of Atopic Dermatitis (Odd ratio=0.206 and p < /em>=0.064). A significantly increased risk of Atopic Dermatitis in heterozygous samples was also observed (Odd=0.158 and p < /em>=0.090). CONCLUSIONS: The results of this study showed that some alleles of DLA-DRB1 gene can play a role in the sensitivity or resistance to Atopic Dermatitis in dogs.

BACKGROUND: Major histocompatibility complex (MHC) comprises a group of genes, which plays a central role in immune response. The exon 2 of BuLA-DRB3 is part of the MHC class II in buffalo that highly polymorphic, found to be associated with resistance/susceptibility to infections and also with production parameters. OBJECTIVES: The purpose of the present study is to identify BuLA-DRB3 polymorphism in Khuzestan buffaloes and compare this population with other Iranian and world buffalo populations. METHODS: Blood samples were taken from 136 unrelated Khuzestan river buffaloes. After DNA extraction, second exon of BuLA-DRB3 was amplified by the seminested PCR method. Then, the fragments produced by amplifying second exon were cut by RsaI restriction enzyme according to van Eijik method. In the following, allelic frequencies, genotype frequencies, expected and observed homozygosty and heterozygosity were calculated. RESULTS: In restriction fragment analysis 13 and 24 different allelic and genotype patterns were identified for RsaI restriction enzyme, respectively. 10 out of 13 alleles were previously reported. The most frequent genotype was oo)0.1691) and then followed by hh (0.1544) ,ll(0.1103), lw (0.0955), lh (0,0808), ha (0.0661) and lo (0.0514). Also four most frequent alleles were o (0.2721), h (0.2316),l (0.2316)and w (0.1176), respectively. These seven genotypes and four alleles form 72.76% and74.29% overall genotype and allele frequency of population.  In addition, estimation of heterozygosity/homozygosty and deviation from Hardy-Weinberg equilibriumofcorresponding population revealed observed homozygosty is more than heterozygosity and departure of population from Hardy-Weinberg equilibrium. CONCLUSIONS: The results indicated that exon 2 of the BuLA-DRB3 gene is highly polymorphic among Khuzestan buffaloes and although, there is differences between buffalo’s genetic polymorphism of distinct world regions, Khuzestan buffaloes’ population is similar to Egyptian buffaloes’ population.