Abstract: 【Objective】Based on the results of the previous genome-wide association on the sheep meat traits, we studied the possibility of the RIPK2 gene to be a novel candidate gene for the sheep growth traits, in order to confirm the GWAS results, as well as to find new molecular markers related to the sheep growth traits.【Method】In the 343 Ujumqin sheep experiment group, 30 DNA samples with a fixed concentration were selected to construct the DNA pool, primers were designed to extend exons and 1 000 bp of upstream and downstream regulate regions. PCR products were tested and the objective strap were sequenced. The sequence peak maps were analyzed by DNAMAN and Chromas2 softwares, Sequenom Mass-array technology was used to genotype the detected SNP including the SNP obtained by previous GWAS. Haploview was used to construct haplotypes and analyze linkage disequilibrium of the polymorphic loci. Association analysis between the SNPs in RIPK2 gene and the growth traits were performed using SPSS 22.0 software. 【Result】 Four SNPs were detected. In exon 4 was a A5536G synonymous mutation rs01, there were three genotypes on this site and the frequencies of AA, AG and GG were 0.42,0.45 and 0.13 individually, the dominant allele was A with a frequency of 0.65. In exon 7 was a T8952C missen variation rs02 with three genotypes. The frequencies of TT, TC and CC genotypes were 0.82,0.16 and 0.02. T was the dominant allele and its frequency was 0.9. Rs05 was a T2836C mutation in exon 10 with only two genotypes TT and CC. The frequency of genotype TT was 0.25 as well as CC was 0.75. In the upstream regions a G5181C variation rs30 was detected with three genotypes GG, GC and CC. The frequency of heterozygous genotype GC was 0.50 and the other two genotypes CC, GG were 0.18 and 0.32 respectively. G was the dominant allele with its frequency was 0.58.The variation T4456C detected by GWAS was rs34 in this study and there were three genotypes. The frequency of TT genotype was 0.49, the frequency of TC was 0.37 and the frequency of CC was 0.14.T was the dominant allele with a frequency of 0.68. The χ² test indicated all the SNPs fit with Hardy-Weinberg equilibrium except rs34. Rs02 was in low polymorphic status (PIC＜0.25) and the other three SNPs were in moderate polymorphic status (0.25＜PIC＜0.5). Linkage disequilibrium analysis suggested that, rs01 and rs02 were strongly linked, the two sites constructed three haplotypes in the experiment population, AT was the dominant haplotype and the frequency was 0.645. Combining the genotypes of the two sites, we found 6 genotype combinations. AATT was the superior genotype and its frequency was 0.425. Single SNP correlation analysis revealed that: on rs01 site, individuals with genotype AA/AG genotype were significantly higher than those with GG genotype on four months body weight, chest girth and six months body height, chest girth (P＜0.05). On rs02 site, individuals with CC genotype were significantly higher on the four months weight, body height, chest girth and six months chest width (P＜0.05) than the individuals with TT and TC genotypes as well as individuals with CC genotype were extremely significantly different from individuals with TT and TC on the four months body length, six months body height and body length (P＜0.01). Individuals with GG genotype on rs30 site showed a significant difference with the individuals of the other two genotypes on the four months weight and chest girth (P＜0.05) and individuals with each genotype had a significant difference on the six months chest girth (P＜0.05). Individuals with each genotype of rs34 had significant difference on the four months weight (P＜0.05). Meanwhile, the combined genotype of rs01-rs02 correlation analysis revealed that: individuals with GGCC combined genotype was significantly different from individuals with the other five genotypes on the four months body weight, body height, body length, chest girth and six months body height, body length and chest width with (P＜0.05).【Conclusion】The results showed that the different SNPs and combined genotypes in RIPK2 gene had effect on Ujumqin sheep different growth traits with the SNPs being potentially valuable as genetic markers for economic traits in Ujumqin sheep.

Key words: RIPK2 gene, growth traits, polymorphisms, association, Ujumqin sheep