Abstract P6-08-22: Racial and ethnic variation in multi-gene panel genetic test results among individuals referred for genetic counseling at a large urban comprehensive cancer center
Authors: Simon Michael Steven , Abdallah Nadine , Assad Hadeel , Surapaneni Malini , Reagle Rachel , Petrucelli Nancie , Purrington Kristen 
Published: March 2020

Background There are racial and ethnic differences in the prevalence and types of pathogenic mutations and variants of uncertain significance (VUS) in BRCA1 and BRCA2. Since the landmark May 13, 2013 Supreme Court Ruling invalidating the patent for BRCA1 and BRCA2 genetic testing, numerous gene panels have been utilized to identify individuals at high risk for hereditary disease due to mutations in other cancer predisposing genes. To better understand the prevalence of recurring pathogenic mutations and/or uncover novel mutations in specific racial and ethnic groups, we evaluated the mutational profile of individuals who had genetic counseling and testing at a large urban NCI designated Comprehensive Cancer Center. Methods Data was extracted from the Karmanos Cancer Institute (KCI) Cancer Genetic Counseling Service data base from May 13, 2013 through December, 31, 2018. The cohort consisted of 3,544 unrelated individuals evaluated for high-risk of hereditary disease and 1,868 who had panel testing at 6 sites across Michigan including Detroit. We estimated the prevalence of pathogenic mutations and VUS from multigene panels by race and ethnicity. Odds Ratios (OR) and 95% confidence intervals (CI) were calculated to compare the rate of pathogenic mutations and VUS in race and ethnic groups with non-Hispanic whites (NHW) indicated as the reference group. Results There were 1,868 (52.7%) individuals who had panel testing which included 67.4% NHW, 24.1% African American (AA), 2.2% Arab, 1.9% Ashkenazi Jewish (AJ), 1.0% Hispanic (H), and 3.4% other. There were 174 individuals with pathogenic mutations and 312 with VUS. Compared to NHW, AA individuals were less likely to have pathogenic mutations on multi-panel testing (OR, 95% CI, 0.20, 0.10-0.37) and more likely to have VUS (OR, 95% CI, 1.41, 1.07-1.85). There were no differences in pathogenic mutations or VUS for other race or ethnic groups. Within a common 18 gene panel (excluding BRCA1 and BRCA2), the five most common genes with a pathogenic mutation were ATM (23), CHEK2 (21), PALB2 (13) and MSH6 (11). The three most common genes and number of pathogenic mutations identified by race and ethnicity were NHW (ATM -21, CHEK2-21&MSH6 -8), AA (MSH6-1, RAD51C-1&TP53-1), and Arab (PALB2-2, RAD50-1 and BARD1-1). For AJ individuals there were 2 pathogenic mutations identified in the MSH6 gene. There were no pathogenic mutations seen in Hispanics. Conclusions Understanding the prevalence of mutations in multi-gene panels in specific racial and ethnic groups can lead to better identification of individuals at risk for hereditary cancer who can benefit from enhanced surveillance and risk reducing management.

Citation Format: Michael Steven Simon, Nadine Abdallah, Hadeel Assad, Malini Surapaneni, Rachel Reagle, Nancie Petrucelli, Kristen Purrington. Racial and ethnic variation in multi-gene panel genetic test results among individuals referred for genetic counseling at a large urban comprehensive cancer center [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P6-08-22.