ABCB1 and inflammatory bowel disease: The advantage of haplotype analysis in relation to the role of ABCB1 gene in IBD pathogenesis has been confirmed by Potocnik et al. They found that haplotype defined by the T–T–T alleles (1236T–2677T–3435T) is significantly associated with a higher risk of developing refractory CD (OR = 3.1, p = 0.04) and UC (OR = 1.6, p = 0.03), what was not true for each of these SNPs analysed separately [52].