Exploring the Role of the Gene in Breast, Ovarian and Endometrial Cancer.

Background: germline monoallelic variants have been detected in a number of patients affected by breast/ovarian cancer or endometrial cancer, suggesting a potential susceptibility role, though their significance remains elusive since the disease mechanism is normally recessive. Hence, the aim of this research was to explore the hypothesis that a second hit could have arisen in the other allele in the tumor tissue.

Methods: we used Sanger sequencing and immunohistochemistry to search for a second variant in the tumoral DNA and to assess protein expression, respectively.

Results: we detected one variant of unknown significance, one variant with conflicting interpretation of pathogenicity and three benign/likely benign variants; the protein was not detected in the tumor tissue of half of the patients, and in others, its expression was reduced.

Conclusions: our results fail to demonstrate that germinal monoallelic variants increase cancer risk through a LOH (loss of heterozygosity) mechanism in the somatic tissue; however, the absence or partial loss of the protein in many tumors suggests its dysregulation regardless of genetic status.