Screening of HELQ in breast and ovarian cancer families

Several high and moderate risk alleles have been identified for breast and ovarian cancer predisposition and most of them encode proteins that function in DNA repair. A prospective candidate for breast and ovarian cancer susceptibility is the HELQ helicase that has a role in the resolution of DNA interstrand cross-links. HELQ interacts with the RAD51 paralog complex BCDX2. Two components of the complex, RAD51C and RAD51D, increase the risk of ovarian cancer especially, and the other two, RAD51B and XRCC2 have been associated with breast cancer risk. To investigate the role of HELQ in cancer predisposition, we screened the gene for germline variation in 185 Finnish breast or ovarian cancer families and performed haplotype analyses for 1517 breast cancer cases, 308 ovarian cancer cases, and 1234 population controls using five common polymorphisms at the HELQ gene locus. No truncating mutations were identified among the families. One putatively pathogenic missense mutation c.1309A>G was identified but no additional carriers were observed in the subsequent genotyping of 332 familial breast or ovarian cancer patients. Furthermore, the haplotype distribution did not differ between breast or ovarian cancer cases and population controls. Our results indicate that HELQ is not a major breast and ovarian cancer susceptibility gene in the Finnish population. However, we cannot rule out rare risk-variants in the Finnish or other populations and larger datasets are needed to further assess the role of HELQ especially in ovarian cancer predisposition.