Candidate gene analysis of the IL12B gene in Crohn's disease

il - 12b是克罗恩病（CD）的潜在易感基因之一。本研究的目的是对日本CD患者IL-12B的候选基因进行分析，并确定该风险等位基因如何影响CD的易感性。因此，我们在外周血单核细胞中检测IL-12B mRNA的等位基因表达失衡。共检查了364例CD患者、242例溃疡性结肠炎患者和445例健康对照（hc）。对IL12B周围的8个snp进行了基因分型。在lps刺激的单核细胞中，采用SNaPshot分析检测IL12B-mRNA的等位基因比例。2个SNP （rs6887695、rs41292470）与CD有显著相关性（Pc分别为0.012、0.020），1个SNP （rs3212227）与CD有边际相关性（Pc = 0.10）。这三个snp形成的单倍型A与CD有显著相关性（Pc = 0.00054，优势比= 1.46）。在10例健康对照的lps刺激单核细胞中，由A单倍型转录到非危险单倍型（单倍型B）的IL12B-mRNA的等位基因比率显著高于各自基因组DNA的等位基因比率（p= 0.00069）。我们证实了IL12B的单倍型1与日本人的CD之间存在关联。等位基因表达失衡支持了IL12B的风险单倍型通过增加IL12B mrna的表达而导致CD易感性的观点。

IL12B is one of the promising candidates for susceptibility genes to Crohn's disease (CD). The aim of this study was to do a candidate gene analysis of IL12B in Japanese CD, and to determine how the risk allele affects the susceptibility to CD. Therefore, allelic expression imbalance of IL-12B mRNA was determined in peripheral monocytes. A total of 364 patients with CD, 242 patients with ulcerative colitis (UC) and445 healthy controls (HCs) were examined. Eight SNPs around IL12B were genotyped. The allelic ratio of IL12B-mRNA was examined using SNaPshot analysis in LPS-stimulated monocytes. Two SNPs (rs6887695, rs41292470) were significantly associated with CD (Pc = 0.012, 0.020, respectively) and one SNP (rs3212227) showed an association with marginal significance (Pc = 0.10). Haplotype A formed by these three SNPs showed significant association with CD (Pc = 0.00054, odds ratio = 1.46). The allelic ratios of IL12B-mRNA transcribed from the haplotype A to the non-risk haplotype (haplotype B) in LPS-stimulated monocytes from ten healthy controls heterozygous for the risk haplotype were significantly higher than the allelic ratio of respective genomic DNA (p= 0.00069). We confirmed the association of the haplotype 1 of IL12B with Japanese CD. The demonstrated allelic expression imbalance supports the idea that the risk haplotype of IL12B confers susceptibility to CD through increasing expression of IL12B-mRNA.