Germline Co-deletion of CDKN2A and CDKN2B Genes in Pleomorphic Xanthoastrocytoma: Case Report.

BACKGROUND/AIM: Gliomas are highly heterogeneous malignancies originating from diverse cell types within the brain. Although their precise etiology is frequently unknown, risk factors, such as chemical exposure, radiation, and specific uncommon genetic disorders have been identified. Diagnosis typically entails imaging tests, such as magnetic resonance imaging and computed tomography, complemented by a biopsy for confirmation, which may be further validated through genetic testing. CASE REPORT: Next-generation sequencing technology revealed germline co-deletion deletion of cyclin-dependent kinase inhibitor 2 A and B genes (CDKN2A and CDKN2B) in a patient diagnosed with pleomorphic xanthoastrocytoma based on the tumor's molecular characteristics. Following this result, we performed focused genetic analysis with use of multiplex ligation-dependent probe amplification technology for the mother that revealed the same co-deletion. Moreover, due to the father's neuroendocrine pancreatic cancer, application of the NGS technology detected a pathogenic variant in the BRCA1-interacting helicase 1 (BRIP1) gene. Comprehensive multi-gene testing conducted within the familial context, marked by a varied spectrum of cancer type, revealed a constellation of genetic predispositions. CONCLUSION: This case study underscores the critical importance of molecular testing for tumor characterization and highlights the pivotal role of genetic testing in facilitating early intervention and screening for at-risk family members. Furthermore, the identification of germline co-deletions in cancer lays the foundation for the development of targeted therapeutic strategies aimed at restoring normal cellular regulation and improving patient management.

Only 32.3% of Breast Cancer Families with Pathogenic Variants in Cancer Genes Utilized Cascade Genetic Testing.

BACKGROUND: Hereditary cancer predisposition syndromes are responsible for approximately 5-10% of all diagnosed cancer cases. In order to identify individuals at risk in a cost-efficient manner, family members of individuals carrying pathogenic alterations are tested only for the specific variant that was identified in their carrier relative. The purpose of this study was to investigate the clinical use and implementation of cascade family testing (CFT) in families of breast cancer patients with pathogenic/likely pathogenic variants (PVs/LPVs) in cancer-related predisposition genes. METHODS: Germline sequencing was carried out with NGS technology using a 52-gene panel, and cascade testing was performed by Sanger sequencing or MLPA. RESULTS: In a cohort of 1785 breast cancer patients (families), 20.3% were found to have PVs/LPVs. Specifically, 52.2%, 25.1%, and 22.7% of patients had positive findings in high-, intermediate-, and low-penetrance breast cancer susceptibility genes, respectively. Although CFT was recommended to all families, only 117 families (32.3%) agreed to proceed with genetic testing. Among the first-degree relatives who underwent CFT, 70.3% were female, and 108 of 121 (89.3%) were cancer free. Additionally, 42.7%, 36.7%, and 20.6% were offspring, siblings, and parents of the subject, respectively. Our data suggest that CFT was mostly undertaken (104/117, 88.8%) in families with positive findings in high-risk genes. CONCLUSIONS: Cascade family testing can be a powerful tool for primary cancer prevention by identifying at-risk family members. It is of utmost importance to implement genetic counseling approaches leading to increased awareness and communication of genetic testing results.

Copy Number Variations (CNVs) Account for 10.8% of Pathogenic Variants in Patients Referred for Hereditary Cancer Testing.

BACKGROUND/AIM: Germline copy number variation (CNV) is a type of genetic variant that predisposes significantly to inherited cancers. Today, next-generation sequencing (NGS) technologies have contributed to multi gene panel analysis in clinical practice. MATERIALS AND METHODS: A total of 2,163 patients were screened for cancer susceptibility, using a solution-based capture method. A panel of 52 genes was used for targeted NGS. The capture-based approach enables computational analysis of CNVs from NGS data. We studied the performance of the CNV module of the commercial software suite SeqPilot (JSI Medical Systems) and of the non-commercial tool panelcn.MOPS. Additionally, we tested the performance of digital multiplex ligation-dependent probe amplification (digitalMLPA). RESULTS: Pathogenic/likely pathogenic variants (P/LP) were identified in 464 samples (21.5%). CNV accounts for 10.8% (50/464) of pathogenic variants, referring to deletion/duplication of one or more exons of a gene. In patients with breast and ovarian cancer, CNVs accounted for 10.2% and 6.8% of pathogenic variants, respectively. In colorectal cancer patients, CNV accounted for 28.6% of pathogenic/likely pathogenic variants. CONCLUSION: In silico CNV detection tools provide a viable and cost-effective method to identify CNVs from NGS experiments. CNVs constitute a substantial percentage of P/LP variants, since they represent up to one of every ten P/LP findings identified by NGS multigene analysis; therefore, their evaluation is highly recommended to improve the diagnostic yield of hereditary cancer analysis.