Wendt C, Muranen TA, Mielikäinen L, Thutkawkorapin J, Blomqvist C, Jiao X, Ehrencrona H, Tham E, Arver B, Melin B, Kuchinskaya E, Stenmark Askmalm M, Paulsson-Karlsson Y, Einbeigi Z, von Wachenfeldt Väppling A, Kalso E, Tasmuth T, Kallioniemi A, Aittomäki K, Nevanlinna H, Borg Å, Lindblom A
Sci Rep 11 (1) 14763 [2021-07-20; online 2021-07-20]
The risk of breast cancer associated with CHEK2:c.1100delC is 2-threefold but higher in carriers with a family history of breast cancer than without, suggesting that other genetic loci in combination with CHEK2:c.1100delC confer an increased risk in a polygenic model. Part of the excess familial risk has been associated with common low-penetrance variants. This study aimed to identify genetic loci that modify CHEK2:c.1100delC-associated breast cancer risk by searching for candidate risk alleles that are overrepresented in CHEK2:c.1100delC carriers with breast cancer compared with controls. We performed whole-exome sequencing in 28 breast cancer cases with germline CHEK2:c.1100delC, 28 familial breast cancer cases and 70 controls. Candidate alleles were selected for validation in larger cohorts. One recessive synonymous variant, rs16897117, was suggested, but no overrepresentation of homozygous CHEK2:c.1100delC carriers was found in the following validation. Furthermore, 11 non-synonymous candidate alleles were suggested for further testing, but no significant difference in allele frequency could be detected in the validation in CHEK2:c.1100delC cases compared with familial breast cancer, sporadic breast cancer and controls. With this method, we found no support for a CHEK2:c.1100delC-specific genetic modifier. Further studies of CHEK2:c.1100delC genetic modifiers are warranted to improve risk assessment in clinical practice.