SLC22A4 and inflammatory bowel disease: The risk variant (rs1050152) of SLC22A4 for IBD occurs in exon 9 where a cytosine is substituted with a thymidine at position 1507 of the coding sequence, resulting in a phenylalanine (F) replacement of the normal leucine (L) amino acid at position 503 of the SLC22A4 protein [18].