Abstract 5228: Genome-wide association study and LD score regression analysis for cholangiocarcinoma
Authors: Han Younghun , McGlynn Katherine A. , Byun Jinyoung , Cooley Matthew A. , Hassan Manal M. , Amos Christopher I. , Roberts Lewis R. ,   The International Consortium for the Genetics of Biliary Tract Cancers
Published: April 2023

Abstract
Cholangiocarcinoma (CCA) is a rare and aggressive cancer of the bile ducts, with a poor prognosis and limited treatment options. CCA are classified as intrahepatic and extrahepatic based on anatomical location. CCA are often diagnosed at an advanced stage because there are no effective tools for early detection. Although genome-wide association studies (GWASs) have discovered many genome-wide significant contributing risk loci, the genetic underpinning of cholangiocarcinoma remains poorly understood. To date, there is no cholangiocarcinoma-specific GWAS. We conducted GWAS of cholangiocarcinoma in 9,648 individuals of European ancestry using TOPMed reference panel. The putative associations in or near THSD7A on chromosome 7 (OR=2.61, P=7.13 × 10−8), ZBTB16 on 11 (OR=0.16, P=6.02 × 10−8) for non-PSC-related CCA, PUM3 on 9 (OR=10.74, P=6.12 × 10−8), AGBL1 on 15 (OR=2.08, P=5.67 × 10−8) for PSC-related CCA, and LINC02506 on 4 (OR=0.16, P=8.83 × 10−9) for extrahepatic CCA. We also implemented linkage disequilibrium score regression (LDSR) analysis to quantify the genetic correlation between phenotypes using publicly available GWAS summary statistics. Our study aimed to identify possible clinical and epidemiological traits associated with CCA. We identified numerous biomarkers, medical conditions, environmental and behavioral traits, and physical measurements showing high heritability, which is the proportion of phenotypic variance explained by all SNPs included in the analysis, and pairwise genetic correlation with CCA and other CCA subtypes. Elevations of selected biomarkers such as alkaline phosphatase, cystatin C, HbA1c, monocyte count, and white blood cell count show a positive genetic association with CCA in European-ancestry population. Also, autoimmune-mediated conditions show a strong positive genetic association with CCA, non-PSC related CCA, and intrahepatic CCA. The GWAS of CCA and CCA subtypes revealed potential genetic susceptibility associations and will allow us to compare the genetic architecture underlying CCA and other diseases of the bile ducts such as primary sclerosing cholangitis and liver cancer. LDSR provided an improved understanding of the genetic architecture between CCA and potential comorbid conditions and biomarkers. Mendelian randomization analysis will be needed to elucidate the causal relationship between CCA and traits of interest.
Citation Format: Younghun Han, Katherine A. McGlynn, Jinyoung Byun, Matthew A. Cooley, Manal M. Hassan, Christopher I. Amos, Lewis R. Roberts, The International Consortium for the Genetics of Biliary Tract Cancers. Genome-wide association study and LD score regression analysis for cholangiocarcinoma. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 5228.