ARHGAP15 and diverticular disease: The strongest diverticular disease association in Iceland was with 45 correlated (r2>0.97) sequence variants (minor allele frequency (MAF)=17.6–17.8%) in 88 kb region spanning introns 9 and 10 of ARHGAP15 (Rho GTPase-activating protein 15) (Fig. 1a).