['Micro-RNAs (miRNAs) are small, non-coding RNA species considered to fine-tune basic cellular functions by modulating target gene translation and/or mRNA stability. A common G/C polymorphism (rs2910164) in the precursor (pre-) miR-146a gene engaged in NF-κB signaling and apoptosis pathways has been reported to modulate the genetic risk of hepatocellular carcinoma by increased G-allelic production of mature miR-146a. We investigated rs2910164 in a large European-based cholangiocarcinoma (CCA) cohort.', "We recruited 182 CCA patients and 350 controls in three academic medical centers. Genotyping for rs2910164 was performed by PCR-based assays with 5'-nuclease and fluorescence detection. Genotype frequencies were tested for consistency with the Hardy-Weinberg equilibrium using an exact test; allelic and genotypic differences between the patients and controls were assessed by the Chi-square test and Armitage's trend test. Exploratory subgroup analyses included gender, tumor localization (extra- versus intrahepatic CCA) and early-onset CCA.", 'Genotype distributions were consistent with the Hardy-Weinberg equilibrium. No significant differences in either allele or genotype distributions were detected between the CCA and control groups or the respective subgroups investigated. However, there was a trend for a protective effect of the heterozygous single-nucleotide polymorphism state GC, as indicated by an underrepresentation in the CCA group in general (29% vs 35%; P=0.18) and, in particular, for extrahepatic tumor sites (26% vs 35%; OR=0.67; 95% CI, 0.43-1.02; P=0.065).'] Does a common variant in the precursor miR-146a sequence predispose to cholangiocarcinoma in a large European cohort?