The clinical and molecular characteristics of patients with personal or family history of gastrointestinal malignancies/polyposis and checkpoint kinase 2 (CHEK2) mutations.

Abstract

44 Background: Checkpoint Kinase 2 (CHEK 2) encodes the protein CHK2, a serine/threonine kinase involved in pathways that conduct DNA repair as well as apoptosis in response to initial DNA damage. Germline mutations in the CHEK2 gene are associated with several malignancies such as colon, breast, stomach, prostate, kidney, thyroid and soft tissue cancers. Here, we describe the clinical and molecular characteristics of patients with personal or family history of gastrointestinal (GI) malignancies/polyposis and CHEK2 gene mutations. Methods: This is an IRB-approved retrospective chart-review study. Between 2016 and 2020, 1011 unique genetic counseling visits were conducted. Germline testing was recommended by a certified genetic counselor if medically necessary. All patients with a germline CHEK2 mutation were identified (N = 16). Patients with a CHEK2 mutation and personal and family history of GI malignancies/polyposis were further explored and their clinical and molecualr characteristics are summarized. Results: The reasons for referral to the Cancer Genetics Counseling Services in patients with pathogenic CHEK2 mutations were personal history of colon cancer (N = 3) and family history of colon cancer (N = 4). One patient with the CHEK2 c.1100delC mutation had a personal history of juvenile polyposis syndrome and a family history of colon cancer. In our cohort, 11 out of 16 (69%) patients had a CHEK2 mutation and personal or family history of GI malignancies/polyposis. The median age was 57 years old (25-80). Six (55%) patients were males. All (100%) patients were Caucasians. Seven (64%) patients had a pathogenic germline CHEK2 mutation and 4 (36%) patients had a variant of unknown significance (VUS). Among patients with pathogenic germline CHEK2 mutations (N = 7), 5 (72%) patients had CHEK2 c.1100delC mutation, 1 (14%) patient had CHEK2 c.190G > A mutation and 1 (14%) patient had CHEK2 c.470T > C mutation. The CHEK2 VUS mutations seen in our cohort were CHEK2 c.539G > A, CHEK2 p.V395L, CHEK2 gain of exons 3-15 and CHEK2 c.1421G > A mutations. Conclusions: All patients in our cohort with CHEK2 mutations were Caucasians. The majority of our patients (69%) had an underlying personal or family history of GI malignancies/polyposis. In patients with personal or family history of GI malignancies/polyposis and CHEK2 mutation, 64% were found to have pathogenic CHEK2 mutations. The most common diagnosed CHEK2 mutation in our cohort was CHEK2 c.1100delC mutation.