Background: Variants of myosin IXB (MYO9B) gene, encoding for a motor protein implicated in epithelial permeability, have been recently associated with inflammatory bowel disease.
Aims: To investigate the contribution of three polymorphisms of MYO9B gene for predisposition to Crohn's disease and ulcerative colitis, their association with clinical phenotypes, particularly intestinal permeability, and possible interaction with the CARD15 gene.
Methods: 549 Crohn's disease patients, 658 ulcerative colitis patients and 674 controls were genotyped for the rs962917, rs1545620 and rs2305764 single nucleotide polymorphisms.
Results: Highly significant genotypic association with Crohn's disease and ulcerative colitis was shown for all three single nucleotide polymorphisms, with odds ratio ranging from 1.5 to 1.7 (P-value: <0.01 to <0.002). A significant difference in allele frequencies was also observed in inflammatory bowel disease patients, with the single most significant association for rs1545620, detected in 47% of Crohn's disease, 47% of ulcerative colitis patients and 42% of controls (P < 0.005). No association with specific sub-phenotypes was found, with the exception of a trend towards an abnormal intestinal permeability (P = 0.043) in Crohn's disease carrying the rs1545620 risk allele.
Conclusions: Our findings confirm the association between the MYO9B polymorphisms and susceptibility to both ulcerative colitis and Crohn's disease, with a weak influence on sub-phenotypic expression.