Open Access

CASE REPORT

Double Heterozygosity in the BRCA1/2 Genes in a Turkish Patient with Bilateral Breast Cancer: A Case Report

Neslihan Duzkale^1,*, Nilnur Eyerci²

1 Department of Medical Genetics, Diskapi Yildirim Beyazit Training and Research Hospital, Ankara, Turkey
2 Department of Medical Biology, Faculty of Medicine, Kafkas University, Kars, Turkey

* Corresponding Author: Neslihan Duzkale. Email:

Oncologie 2020, 22(3), 161-166. https://doi.org/10.32604/oncologie.2020.014116

Abstract

BRCA1 and BRCA2 tumor suppressor genes are responsible for a quarter of hereditary breast cancers. Double heterozygous (DH) pathogenic variant carrier status in these genes is an extremely rare condition, especially in non-Askenazi individuals. We report a woman patient with bilateral breast cancer that carries DH disease-causing variants in BRCA1/2 genes. The 45-year-old patient who was followed up with the diagnosis of metachronous bilateral breast cancer was diagnosed with cancer at the age of 39 and 43, respectively. BRCA1/2 genes of the patient were evaluated using Next-Generation Sequencing. In the patient, the c.2800C>T (p.Gln934Ter) pathogenic variant in BRCA1 and the c.9648+1G>C likely pathogenic variant in BRCA2 were detected as DH. Segregation analysis in family members revealed that her two healthy siblings available for testing were heterozygous for either BRCA1 or BRCA2 variants, but her mother, who had a past diagnosis of ovarian cancer, was heterozygous for both BRCA1 and BRCA2 variants. Germline double heterozygosity in inherited cancer is a rare condition, and as far as we know it is reported for the first time from patient population in Turkey. Large-scale patient series are needed to determine the impact of double heterozygosity on diseases course, such as prognosis and treatment responses.

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