BRCA1 Haploinsufficiency and Gene Expression

Overview

The purpose of this study is to collect a blood sample from patients that may be used for research purposes. These blood samples will be used by researchers at this institution to study the causes of breast and ovarian cancer, and to better understand how these cancers develop. We are trying to discover differences in the ways cells work in women with a high genetic risk of developing breast or ovarian cancer. Early data suggest that some genes may be turned on or off in different ways based upon whether or not a woman has a high genetic risk of developing breast or ovarian cancer. The primary objective is to test the hypothesis that BRCA1 haploinsufficiency regulates gene expression on the X chromosome. This hypothesis will be tested by comparing the gene expression profiles of BRCA1 heterozygotes (cases) to an age-matched group of unaffected women who are not BRCA1 mutation carriers (controls).

The specific aim of this project is to test the hypothesis that BRCA1 haploinsufficiency regulates gene expression on the X chromosome. This hypothesis will be examined by determining if X chromosome gene expression profiles, derived from lymphocyte RNA, of BRCA1 mutation carriers (cases) can be distinguished from an age-matched group of women who do not have BRCA1 mutations (controls). Neither cases nor controls will have a history of cancer. This investigation will provide valuable insight into the biologic function of BRCA1 and its role in breast and/or ovarian tumorigenesis. Blood samples from cases will be collected from patients who have previously undergone genetic counseling through the Clinical Genetics Service at MSKCC and tested positive for a germline mutation in BRCA1. Blood samples from controls will be obtained from two sources. First from specimens already collected under IRB Protocol #99-030, entitled "Collection of Tissue, Blood, and Cells to be Used for Studying the Causes, Prevention, Diagnosis, and Treatment of Breast Cancer (T. King, PI). Controls will also be collected from patients who have previously undergone genetic counseling through the Clinical Genetics Service at MSKCC and tested negative for germline mutations in BRCA1. Isolation of total RNA from blood will be performed using the PAXgene™ Blood RNA System. This study will use lymphocyte RNA samples from 50 individuals with BRCA1 mutations and 50 age-matched controls. Gene expression profiling will be performed in the Genomics Core Laboratory of MSKCC under the supervision of Agnes Viale, PhD. Class comparison analysis will be performed on the gene expression data in the Biostatistics Department under the supervision of Adam Olshen, PhD. It is anticipated that this study will be completed in approximately 1 year.