Assoiciation Of Polymorphisms Of DQB2Exon2and Exon3with Abortion Trait In Hexi Cashmere Goat

This experiment was conducted to study the polymorphism analysis ofMHC-DQB2exon2and exon3in Hexi cashmere goat by PCR-SSCP method toprovide a molecular basis for goat breeding of disease resistance.The results showed that DQB2gene exon2and exon3appeared polymorphic.Sequencing analysis found ten alleles in exon2, which exist31point mutations,including four single-point mutations: in the30bp at alleleY7C�'A, did not causeamino acid changes;38bp at alleleY9A�'T, histidine�'leucine;40bp at all allelesC�'T, did not cause amino acid changes;149bp at alleleY5C�'A, proline�'histidine.Allele Y8was the dominant allele. There were15genotypes and8alleles inexon3,which exist35piont mutations. Variable sites were26、32、71、77、106、115、124、141、163、164、194、206、217、238G�'A;53、57、83、149、182、191、198、209、212、236、237、239C�'T;55、203、204A�'G;137、167T�'C;123、152C�'A;140A�'C;191、239C�'G;227G�'C. Genotype GG was the dominantgenotype, allele C was the dominant allele.Ploymorphism index analysis, the PIC was0.7657(PIC>0.5) in exon2, and thePIC was0.8385(PIC>0.5) in exon3, these two sites were in highly polymorphic;Chi-square test indicated that the polymorphic locus in Hexi cashmere goat were atHardy-Weinberg equilibrium both exon2and exon3: χ~2=14.766,P=0.098(>0.05)exon2; χ~2=8.348, P=0.303(>0.05) exon3.The phylogenetic tree results showed that the MHC-DQB2exon2of Hexicashmere goat can divide into two clusters, and cattle and goat appeared a highhomology in the site.Exon3was originally by mutations in both alleles at Bovine andOvis, and sheep and goat appeared a high homology in the site.A bortion trait analysis, results showed that exon2and exon3may not appearrelationship with abortion.