Association between Missense Variants of Uncertain Significance in CHEK2 Gene and Hereditary Breast Cancer: A Co-segregation and Bioinformatics Analysis

Natalia Alonso^{1, 2*} SEBASTIAN MENAO^{2, 3} Rodrigo Lastra^{2, 3} María Arruebo^{2, 3} María Pilar Bueso^{2, 3} Esther Pérez³ Manuela Laura Murillo^{2, 3} María Álvarez^{2, 3} Alba Alonso⁴ Soraya Rebollar³ Mara Cruellas^{2, 5} Dolores Arribas³ Mónica Ramos³ DOLORES ISLA^{2, 3} Juan José Galano-Frutos^{6, 7} Helena García-Cebollada^{6, 7} Javier Sancho^{2, 6, 7} Raquel Andrés^{2, 3}

• ¹Hospital San Pedro, Spain
• ²Service of Pathology, Aragon Institute for Health Research (IIS Aragon), Spain
• ³Lozano Blesa University Clinical Hospital, Spain
• ⁴University Hospital Arnau de Vilanova, Spain
• ⁵Vall d'Hebron University Hospital, Spain
• ⁶University of Zaragoza, Spain
• ⁷University Institute of Biocomputation and Physics of Complex Systems, University of Zaragoza, Spain

Inherited mutations in the CHEK2 gene have been associated with an increased lifetime risk of developing breast cancer (BC). We aim to identify in the study population the prevalence of mutations in CHEK2 gene in diagnosed BC patients, to evaluate the phenotypic characteristics of the tumor and family history, and to predict the deleteriousness of the variants of uncertain significance (VUS). A genetic study was performed, from May 2016 to April 2020, in 396 patients diagnosed of BC at the University Hospital Lozano Blesa of Zaragoza (Spain). Patients with a genetic variant in the CHEK2 gene were selected for the study. We performed a descriptive analysis of the clinical variables, a bibliographic review of the variants and a cosegregation study when possible. Moreover, an in depth bioinformatics analysis on CHEK2 VUS was carried out. We identified 9 genetic variants in the CHEK2 gene, in 10 patients (2 pathogenic variants and 7 VUS). This supposes a prevalence of 0.75% and 1.77% respectively. In all cases there was a family history of BC in first and /or second-degree relatives. We carried out a cosegregation study in two families, being positive in one of them. The bioinformatics analyses predicted the pathogenicity of 6 of the VUS. In conclusion, CHEK2 mutations have been associated with increased risk for BC. This risk is well established for foundation variants. However, the risk assessment for other variants is unclear. The incorporation of bioinformatics analysis provided supporting evidence of the pathogenicity of VUS.