The polymorphisms in DLG5 (113 G-->A, 4136 C-->A, and DLG5_e26), SLC22A4 (1672 C-->T), and SLC22A5 (-207 G-->C) were assessed in 625 patients with Crohn's disease (CD), 363 patients with ulcerative colitis (UC), and 1012 healthy controls.
The TC haplotype, composed of L503F in SLC22A4 and -207G/C in SLC22A5 promoters, was reported to alter the function of the organic cation transporter and to be associated with CD in Caucasians.
Phenotype-genotype associations were evaluated in a Canadian cohort including 507 patients with CD, 216 patients with UC, and 352 ethnically matched controls genotyped for SLC22A4 C1672T, SLC22A5G-207C, and the major CD-associated CARD15 variants.
The frequency of the NOD2/CARD15 susceptibility variants in the Hungarian pediatric CD population is high and the profile differs from the adult CD patients, whereas the results for SLC22A4 and SLC22A5 mutation screening do not confirm the assumption that the carriage of these genotypes means an obligatory susceptibility to CD.
Association with 11 SNPs spanning the SLC22A4 and SLC22A5 genes, including a putative RA-causing functional polymorphism (rs3792876 [slc2f2]) and a functional haplotype previously associated with CD, was investigated in 909 RA cases and 594 population controls in the UK.
We confirmed a strong association between three NOD2/CARD15 gene variants (Pro268Ser, OR = 2.52, 95% CI = 1.34-4.75); (Arg702Trp, OR = 6.65, 95% CI = 1.99-22.17); (1007fs, OR = 9.59, 95% CI = 3.94-23.29), and a weak association between both the protective OCTN1/OCTN2 CC haplotype (OR = 0.28, 95% CI = 0.08-0.94), and a variant of ATG16L1 gene (Thr300Ala, OR = 0.468, 95% CI = 0.24-0.90) with Crohn's disease.
The article discusses current information on the relation between CARD15 variants and Crohn disease and the discoveries of SLC22A4/SLC22A5 and DLG5 gene variants that also confer risk for inflammatory bowel disease.
Recently, two functional variants in SLC22A4 and SLC22A5 (L503F and G-207C), encoding the cation transporters OCTN1 and OCTN2, were proposed as causal variants for CD, but with conflicting genetic evidence regarding their contribution.
Recently, a functional haplotype of 2 single-nucleotide polymorphisms (SNPs) mapping to the organic cation transporter (OCTN) genes, SLC22A4 and SLC22A5, was identified as a second Crohn's disease susceptibility locus.
The OCTN1 (SLC22A4 1672C-->T) and OCTN2 (SLC22A5 -207G-->C) variants within the IBD5 locus have been associated with susceptibility to adult onset Crohn's disease (CD), but their contribution in children has not been examined.
Two variants, 1672C>T in SLC22A4 and -207G>C in SLC22A5, were shown to alter these genes' functions and were identified as genetic susceptibility factors for Crohn's disease (CD).
Our data suggest that SNPs and haplotype in the IBD5 SLC22A4/SLC22A5 region contribute to the development of particularly refractory Crohn's disease in the Slovenian population, and expression studies in blood lymphocytes and colon tissue biopsies and eQTL analysis suggest that SLC22A5 is the main gene in the IBD5 region contributing to the IBD pathogenesis.
The G allele of -368T > G in SLC22A5, in which strong linkage disequilibrium was observed and the limited diversity of three haplotypes was estimated, was significantly associated with steroid resistance in Japanese patients with Crohn's disease (P = 0.016).
Recently, two functional variants within the SLC22A4 and SLC22A5 genes at this locus (IBD5), L503F (c.1507C > T) and G-207C (c.-207G > C), have been proposed to contribute directly to susceptibility to CD.
Case-control analysis of the SLC22A4 1672T, SLC22A5-207C diplotype showed significant association (p=0.04) with CD susceptibility compared with controls.
Collectively, our results suggest that the 1672T variant of the OCTN1 gene and the -207C variant of the OCTN2 gene represent risk factors for CD in the Greek population.