Fenocopy

not everything is what seems to be

Abstract

Breast and ovary cancers are highly prevalent phenotypes of the hereditary breast and ovary cancer syndrome (HBOC) associated with germline mutations in one of the susceptible genes BRCA1, BRCA2, RAD51C, PALB2, among others. A phenocopy is an individual whose phenotype, under a particular environmental condition, is identical to the one of another individual whose phenotype is determined by the genotype, someway mimicking the phenotype produced by a gene. In this article we described a woman with breast ductal carcinoma in situ (DCIS) after profilactic bilateral oophorectomy belonging to a family with HBOC whose genetic testing BRCA1 was inconclusive. We insisted with the genetic screening of another affected family member. The genetic testing of her nephew with ovary cancer was clarifying, with the identification of deleterious mutation c.5083del19 in the BRCA1 gene. We concluded that the woman with CDIS was in fact a phenocopy, and developed a sporadic (not hereditary) CDIS.