The present case report discusses a woman affected by chronic lymphatic leukemia and breast cancer with a familial history of breast cancer; suspected to be hereditary breast and ovarian cancer (HBOC) syndrome. The patient underwent BRCA1 and BRCA2 genetic testing. Sequencing of BRCA1 revealed the presence of the variant of unknown significance (VUS) c.3082C>T (p.Arg1028Cys) at homozygous state, whereas no mutations were detected in BRCA2. Multiplex ligation-dependent probe amplification confirmed the presence of two alleles. Although consanguineity between her parents was reported, which therefore supported the molecular data, her clinical phenotype was not suggestive of typical Fanconi anemia (FA), particularly of a BRCA1-linked FA. In the two cases reported in the literature, carriers of biallelic BRCA1 mutation present a severe and quite typical phenotype. For this reason, the patient was offered a diepoxybutane test, where neither complex rearrangements nor multiradial formation were detected. We were therefore inclined to consider that BRCA1 VUS as of little clinical significance.
Keywords: Fanconi anemia; diepoxybutane test; hereditary breast and ovarian cancer syndrome; homozygous BRCA1; p.Arg1028Cys.