Multi-ancestry sequencing analysis in 293,141 participants identifies predisposition DNA repair genes associated with HCC risk.

Genetic testing for Lynch and BRCA1/2-associated hereditary cancer syndromes is recommended in colon or pancreatic cancer patients, but their association with hepatocellular carcinoma (HCC) risk is unknown. We evaluated associations between rare germline variants in DNA-repair genes and HCC risk across ancestrally diverse cohorts. We analyzed whole exome (WES) and whole genome sequencing (WGS) data from 2,594 HCC cases and 290,547 cancer-free controls from diverse biobanks and cohorts: Penn Medicine BioBank, All of Us, Mayo Clinic, ESCALON, and the Million Veteran Program. Participants were classified into six population groups. We focused on six DNA-repair genes previously implicated in HCC: BRCA2, BRIP1, MSH6, PMS2, CHEK2, and FANCA. Gene-level burden analyses of rare predicted loss-of-function (pLoF) and damaging missense variants were performed in European and African populations, and across all six ancestry groups. In the European population, MSH6, a Lynch syndrome-associated gene, had the strongest association with HCC, with a 2.75-fold increased HCC risk at 1% minor-allele frequency (MAF) (OR= 2.75 [1.50, 5.04], P=0.001, FDR q=0.02), while PMS2, showed a nominally significant association at the same MAF threshold (OR=1.90 [1.08, 3.34], P=0.03, FDR q=0.09). Combined analysis across all populations strengthened the MSH6 finding (OR=2.53 [1.43, 4.49], P=0.001, FDR q=0.01) at a MAF of 0.1%. A significant BRCA2 association was also observed in the combined analysis at a MAF of 0.1% (OR=2.26 [1.39, 3.67], P=0.001, FDR q=0.01). Rare variants in MSH6 and BRCA2 are significantly associated with increased HCC risk, revealing a previously unconfirmed role for DNA repair genes in HCC susceptibility across ancestrally diverse populations. These findings may inform genetic risk stratification and surveillance strategies. Rare variants in MSH6 and BRCA2 genes are associated with 2.3 to 2.8-fold higher HCC risk. These findings may warrant further evaluation of liver cancer risk in individuals with MSH6-associated Lynch syndrome or BRCA2-associated hereditary cancer syndromes.