CHEK2 Germline Variants in Cancer Predisposition: Whole Genome Sequencing Results

While pathogenic germline CHEK2 variants are known to increase cancer risk, there is currently insufficient evidence regarding the precise risk of developing malignant neoplasms associated with specific missense variants or variants of uncertain significance. As a result, no clear clinical guidelines exist regarding consultation, monitoring and specific treatment options for those patients. For the first time in Russia, clinical data and whole-genome sequencing (WGS) results were analyzed for 3150 patients with cancer and suspected hereditary cancer syndromes (HCS) and 5163 healthy individuals. This dataset formed the basis for assessing the role of germline CHEK2 variants in the development of different cancer types. The chromosomal coordinates and coding sequence coordinates are given in accordance with the GRCh38 (hg38) genome assembly and the NM_007194.4 transcript. Pathogenic (P) and likely pathogenic (LP) variants of CHEK2 significantly increased the risk of breast cancer (OR = 2.015 [95% CI: 1.27–3.21]; p = 0.0031), but the association with colorectal cancer was not statistically significant (OR = 1.354 [95% CI: 0.42–4.42]; p = 0.616). A moderate increase in cancer risk was identified for the c.1100del variant (OR = 2.263 [95% CI: 1.19–4.32]; p = 0.0132) and for the common P/LP variants c.1100del, c.444+1G>A and c.433C>T (OR = 2.219 [95% CI: 1.40–3.51]; p = 0.0007). Notably, our study confirmed that CHEK2 c.470T>C (p.Ile157Thr) is the most common variant in the patient group, identified in 3.8% of cases (120/3150), compared with 3.0% in the control group (155/5163). Although the association between the most common CHEK2 variant c.470T>C and cancer risk reached nominal statistical significance (OR = 1.279 [95% CI: 1.00–1.63]; p = 0.0463), the effect size was minimal, suggesting that the contribution of this variant to hereditary cancer risk in the Russian population is modest. Additional studies are required before this variant can be definitively excluded from clinical interpretation.