Bias conferred by NOD2 gene coverage, related samples and non-Caucasian ethnicity (Additional file 1: Figure S3) was removed from all IBD cases (n = 6<50x, n = 1relative and n = 20non-Caucasian) and non-IBD control samples (n = 16<50x, n = 4relatives and n = 13non-Caucasian) respectively. Here, NOD2 is linked to inflammatory bowel disease.