DNA repair genes implicated in triple negative familial non-BRCA1/2 breast cancer predisposition

Area of Science:

• Genetics
• Oncology
• Molecular Biology

Background:

• Hereditary breast cancer accounts for 10-15% of cases, with BRCA1/2 mutations found in only 15-20% of familial cases.
• Triple-negative breast cancer (TNBC) is aggressive, lacks targeted therapies, and may have distinct genetic susceptibilities.
• This study investigates novel genetic factors contributing to familial TNBC independent of BRCA1/2 mutations.

Purpose of the Study:

• To identify new susceptibility genes for triple-negative breast cancer (TNBC) in patients with a family history of cancer but no BRCA1/2 mutations.
• To explore the functional impact of identified mutations in tumor tissues.
• To assess the potential for targeted therapies based on identified genetic pathways.

Main Methods:

• Pyrosequencing of 36 candidate genes in 50 TNBC patients from families with hereditary breast cancer (2005-2013).
• Mutation analysis in available relatives.
• Exploration of protein expression and loss of heterozygosity in tumor samples.

Main Results:

• Seven deleterious mutations were found in 6 genes (RAD51D, MRE11A, CHEK2, MLH1, MSH6, PALB2) across 7 patients.
• RAD51D mutation was identified in two patients.
• Loss of heterozygosity and absent protein expression were observed for some mutations, particularly in DNA repair pathways.

Conclusions:

• Specific subtypes of triple-negative breast cancer may be linked to distinct genetic susceptibilities, primarily within the homologous recombination DNA repair pathway.
• Discovery of these genes opens avenues for new targeted therapies and improved patient management.
• Further research into these identified genes is warranted for clinical application.