A de novo BRCA1 gene mutation in a 29-year-old woman with triple negative breast cancer

Introduction:Germline mutations in the BRCA1 and BRCA2 genes lead to a highly increased lifetime risk for breast and ovarian cancer. These mutations are usually inherited and reports of de novo occurrences are a very rare phenomenon.Case Presentation:We report on a breast cancer patient with a de novo BRCA1 mutation c.121C>T, (p.His41Tyr). The pathogenic mutation was detected in leukocyte DNA of a patient with negative family history who had developed early onset, triple negative breast cancer. The mutation was not found in any of the maternal and paternal tissues tested, but was detected in multiple samples representing all three germ layers of the affected carrier, which renders somatic mosaicism unlikely.Conclusion:This case highlights the importance of including early onset of disease and triple negativity of the tumor even in patients even in absence of a family history. Considering the availability of effective treatments in early and advanced BRCA mutation carriers, this finding underscores the importance of genetic testing in all breast cancer patients.