Recently, genetic variants conferring risk for IBD were fine-mapped to single variant resolution. Eight of these causal variants resulted in amino acid substitutions while ten were non-coding. The mechanism by which these non-coding causal variants confer disease risk is unknown, though presumably they influence gene expression by differential binding of transcription factors. SNP rs1887428 is located in the promoter region of Janus kinase 2 (JAK2), an enzyme that interacts with STAT family transcription factors and cytokine receptors to regulate hematopoiesis and the immune response.