A novel approach to genome-wide association analysis identifies genetic associations with primary biliary cholangitis and primary sclerosing cholangitis in Polish patients

Abstract Background Primary biliary cholangitis (PBC) and primary sclerosing cholangitis (PSC) are forms of hepatic autoimmunity, and risk for both diseases has a strong genetic component. This study aimed to define the genetic architecture of PBC and PSC within the Polish population. Methods Subjects were 443 women with PBC, 120 patients with PSC, and 934 healthy controls recruited from Gastroenterology Departments in various Polish hospitals. Allelotyping employed a pooled-DNA sample-based genome-wide association study (GWAS) approach, using Illumina Human Omni2.5-Exome BeadChips and the following novel selection criteria for risk loci: blocks of at least 10 single nucleotide polymorphisms (SNPs) in strong linkage disequilibrium, where the distance between each adjacent SNP pair in the block was less than 30 kb, and each SNP was associated with disease at a significance level of P < 0.005. A selected index SNP from each block was validated using TaqMan SNP genotyping assays. Results Nineteen and twenty-one SNPs were verified as associated with PBC and PSC, respectively, by individual genotyping; 19 (10/9, PBC/PSC) SNPs reached a stringent (corrected) significance threshold and a further 21 (9/12, PBC/PSC) reached a nominal level of significance ( P < 0.05 with odds ratio (OR) > 1.2 or < 0.83), providing suggestive evidence of association. The SNPs mapped to seven (1p31.3, 3q13, 6p21, 7q32.1, 11q23.3, 17q12, 19q13.33) and one (6p21) chromosome region previously ..