Vitamin D receptor (VDR) single-nucleotide polymorphisms (SNPs) modulate vitamin D/VDR signaling, a key pathway in inflammatory bowel disease (IBD) pathogenesis. This study investigates how ApaI, BsmI, TaqI, and FokI SNPs affect IBD phenotype and progression. A total of 76 Crohn's disease (CD) and 68 ulcerative colitis (UC) patients were genotyped. On initial bivariate analysis, the AA genotype of ApaI was accompanied by higher rates of penetrating (B3) CD (36.7% vs. 8.7%