Next-generation sequencing in pooled samples from patients with Crohn's disease and controls identified additional independent risk variants in two of the known risk genes (NOD2 and IL23R), a highly significant association with a protective splice variant in CARD9 (P < 1 × 10−16, odds ratio ∼0.29), and additional associations with coding variants in several genes (IL18RAP, CUL2, C1orf106, PTPN22 and MUC19) (Rivas et al., 2011). Here, CUL2 is linked to Crohn disease.