The First Case Report of a Patient With Oligodendroglioma Harboring CHEK2 Germline Mutation

Checkpoint Kinase 2 (CHEK2) Gene Mutation in a Patient With Breast and Prostate Cancer: A Unique Presentation of a Rare Disease

Breast cancer is one of the rarest malignancies in males, with a low incidence rate compared to all breast cancers. Gene mutation plays a significant role in the pathologic process of cancer. Mutations in breast cancer gene 1 (BRCA1) and breast cancer gene 2 (BRCA2) have been associated with male breast cancer (MBC), as well as prostate cancer (PCa). Despite the etiopathogenetic similarity, combined MBC and PCa is a rare entity. This report presents the case of a 57-year-old male with a history of breast cancer who underwent modified radical mastectomy (MRM) with lymph node dissection followed by adjuvant chemoradiotherapy four years ago. The patient presented with recurrent episodes of voiding dysfunction for three months, followed by urine retention. His family history was positive for breast and lung cancer. High prostate-specific antigen (PSA) and Prostate Imaging-Reporting and Data System 5 (PI-RADS5) necessitate transrectal ultrasound-guided biopsy, which confirmed the diagnosis of PCa. Molecular genetics testing and next-generation sequencing (NGS) analysis identified heterozygous variant c.636T>G, p.(Tyr212*) in the checkpoint kinase 2 (CHEK2) gene. The patient is planned for neoadjuvant luteinizing hormone-releasing hormone (LHRH) for 3-6 months, to be followed by transurethral tunneling of the prostate (TUTP) with adjuvant LHRH. The allele frequency of this patient mutation was documented for the first time among the general population, and it has not been described in the literature. This unique and rare case was presented with clinical, morphological, and immunohistochemical features together with a review of the current literature.

Two Distinct Deleterious Causative Variants in a Family with Multiple Cancer-Affected Patients

Background

Only 5 to 10% of cancers are hereditary, but they are particularly important since they can be passed down from generation to generation, and family members are at elevated risk. Although screening methods are one of the essential strategies for dealing with hereditary cancers, they do not have high specificity and sensitivity. The emergence of whole-exome sequencing (WES) causes a significant increase in the diagnostic rate of cancer-causing variants in at-risk families.

Materials and Methods

We performed WES on the proband's DNA sample from an Iranian family with multiple cancer-affected members to identify potential causative variants. Multiple in silico tools were used to evaluate the candidate variants' pathogenicity and their effects on the protein's structure, function, and stability. Moreover, the candidate variants were co-segregated in the family with Sanger sequencing.

Results

The WES data analysis identified two pathogenic variants (CHEK2: NM_007194.4: c.538C>T, p.Arg180Cys and MLH1: NM_000249.4, c.844G>A, p.Ala282Thr). Sanger sequencing data showed each of the variants was incompletely segregated with phenotype, but both of them explained the patient's phenotype together. Also, the structural analysis demonstrated that due to the variant (c.538C>T), a salt bridge between arginine 180 and glutamic acid 149 was lost. Indeed, several protein stability tools described both variants as destabilizing.

Conclusion

Herein, we interestingly identify two distinct deleterious causative variants (CHEK2: NM_007194.4: c.538C>T, p.Arg180Cys and MLH1: NM_000249.4, c.844G>A, p.Ala282Thr) in a family with several cancer-affected members. Furthermore, this study's findings established the utility of WES in the genetic diagnostics of cancer.

CHEK2 Alterations in Pediatric Malignancy: A Single-Institution Experience

Background: Approximately 10% of pediatric malignancies are secondary to germline alterations in cancer-predisposing genes. Checkpoint kinase 2 (CHEK2) germline loss-of-function variants have been reported in pediatric cancer patients, but clinical phenotypes and outcomes are poorly described. We present our single-institution experience of pediatric oncology patients with CHEK2 germline alterations, including clinical presentations and outcomes. Methods: Pediatric oncology patients with CHEK2 germline alterations were identified among those assessed by clinical or translational research at the Institute for Genomic Medicine at Nationwide Children’s Hospital. A chart review of disease course was conducted on identified patients. Results: We identified 6 patients with germline CHEK2 variants from a cohort of 300 individuals, including 1 patient with concurrent presentation of Burkitt lymphoma and neuroblastoma, 3 patients with brain tumors, 1 patient with Ewing sarcoma, and 1 patient with myelodysplastic syndrome. Three patients had a family history of malignancies. Four patients were in remission; one was undergoing treatment; one patient had developed treatment-related meningiomas. We review prior data regarding CHEK2 variants in this population, challenges associated with variant interpretation, and genetic counseling for individuals with CHEK2 variants. Conclusions: CHEK2 germline loss-of-function alterations occur in patients with a variety of pediatric tumors. Larger multicenter studies will improve our understanding of the incidence, phenotype, and molecular biology of CHEK2 germline variants in pediatric cancers.