On the other hand, C allele and CC genotype of C1236T and C3435T, as well as G allele and GG genotype of G2677T/A were more frequent in healthy subjects, implying protective role of these variants in UC.
The polymorphism Ala893Ser/Thr (G2677T/A) previously showed significant association with Crohn's disease (CD) and the Ile1145Ile (C3435T) with ulcerative colitis (UC).
Heterozygous carriers for the variants C1236T, rs2235046 (an SNP in intron 16), and G2677T/A showed a lower risk of developing ulcerative colitis (C1236T: odds ratio [OR] = 0.63, 95% confidence interval [CI] = 0.42-0.93, P = 0.03; G2677T/A: OR = 0.59, CI = 0.39-0.89, P = 0.02; and rs2235046: OR = 0.59, 95% CI = 0.38-0.91, P = 0.009) as compared with homozygotes.
ABCB1 1236C>T polymorphism significantly affects the therapeutic efficacy of tarcolimus at 12 weeks under the tight dose-adjusting treatment for ulcerative colitis.
The CC genotype and C allele of ABCB1 C1236T polymorphisms are significantly associated with UC susceptibility, so we conclude that ABCB1 C1236T polymorphisms might serve as genetic-susceptibility factors for UC.
Linkage disequilibrium of C3435T with T-129C, C1236T and G2677A, T was suggested to be altered in UC, but the analysis of their haplotype provided no advantage in terms of prediction over that with only C3435T.
In addition, two intronic SNPs in LD with the disease haplotype, one in intron 13 (rs2235035) and another in intron 16 (rs1922242), were significantly associated with refractory Crohn (P=0.026, odds ratio (OR) 2.7 and P=0.025, OR 2.8, respectively), as well as with UC (P=0.006, OR 1.8 and P=0.026, OR 1.9, respectively).
In addition, two intronic SNPs in LD with the disease haplotype, one in intron 13 (rs2235035) and another in intron 16 (rs1922242), were significantly associated with refractory Crohn (P=0.026, odds ratio (OR) 2.7 and P=0.025, OR 2.8, respectively), as well as with UC (P=0.006, OR 1.8 and P=0.026, OR 1.9, respectively).
Heterozygous carriers for the variants C1236T, rs2235046 (an SNP in intron 16), and G2677T/A showed a lower risk of developing ulcerative colitis (C1236T: odds ratio [OR] = 0.63, 95% confidence interval [CI] = 0.42-0.93, P = 0.03; G2677T/A: OR = 0.59, CI = 0.39-0.89, P = 0.02; and rs2235046: OR = 0.59, 95% CI = 0.38-0.91, P = 0.009) as compared with homozygotes.
In patients with extensive UC a significantly different distribution of genotypes of the MDR1 G/A change located in intron 3 (rs3789243) was observed between carriers/noncarriers of the -25385T risk allele (P = 0.005).