Analysis of the influence of OCTN1/2 variants within the IBD5 locus on disease susceptibility and growth indices in early onset inflammatory bowel disease

Background and aims: 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. Methods: These OCTN1/2 variants and IBD5 marker single nucleotide polymorphisms (SNPs) (IGR2096a_1, IGR2198a_1, and IGR2230a_1) were examined in 299 Scottish children (200 with CD, 74 with ulcerative colitis (UC), and 25 with indeterminate colitis (IC)), together with 502 parents (for transmission disequilibrium testing) and 256 controls. Results: All SNPs were in strong linkage disequilibrium (D′ >0.94). TDT analysis showed association of the OCTN1 variant with inflammatory bowel disease (IBD) (p = 0.01) and CD (p = 0.04). Allele frequencies of the OCTN1/2 variants were significantly higher in IBD/CD cases (p