Lack of association of MYO9B genetic variants with coeliac disease in a British cohort

Background and aims: Development of coeliac disease involves an interaction between environmental factors (especially dietary wheat, rye, and barley antigens) and genetic factors (there is strong inherited disease susceptibility). The known human leucocyte antigen (HLA)-DQ2 and -DQ8 association explains only a minority of disease heritability. A recent study in the Dutch population suggested that genetic variation in the 39 region of myosin IXB (MYO9B) predisposes to coeliac disease. MYO9B is a Rho family GTPase activating protein involved in epithelial cell cytoskeletal organisation. MYO9B is hypothesised to influence intestinal permeability and hence intestinal antigen presentation. Methods: Four single nucleotide polymorphisms were chosen to tag all common haplotypes of the MYO9B 39 haplotype block ( exons 15-27). We genotyped 375 coeliac disease cases and 1366 controls ( 371 healthy and 995 population based). All individuals were of White UK Caucasian ethnicity. Results: UK healthy control and population control allele frequencies were similar for all MYO9B variants. Case control analysis showed no significant association of any variant or haplotype with coeliac disease. Conclusions: Genetic variation in MYO9B does not have a major effect on coeliac disease susceptibility in the UK population. Differences between populations, a weaker effect size than originally described, or possibly a type I error in the Dutch study might explain these findings.