Cancer Prevention / News

Genomic Diversity and Cancer Disparities

Timothy Rebbeck, MD Professor of Epidemiology, University of Pennsylvania Perelman School of Medicine

Genomic Diversity and Cancer Disparities

Timothy R. Rebbeck

Professor of Epidemiology
University of Pennsylvania Perlman School of Medicine

Public Health Challenge

Disparities can be separated in to two categories: Differences and inequities. While equity disparities such as discrimination, segregation and access can be modified, difference disparities such as genetics cannot.  

Mutations of BRCA 1 and 2 genes produce increased risk in carriers. In the case of this gene risk, the BRIDGE Study seeks to evaluate the mutation spectrum, founder mutations, evolutionary genetics, cancer risk and risk modifiers by engaging multiethnic cohorts from around the globe.

In most studies race/ethnicity is usually self-reported, complex phenomenon; appropriate definition of these differences is necessary.  Often this personal characteristic is defined by culture, behavior or environment. It may be shaped by the categorizations in use by the census or specific studies.

Research Findings

Risk producing versions of BRCA 1 and 2 among non-white populations account for 20% of all unique mutations (548/2757, CIMBA 2014) Type and location of mutation differs by racial ethnicity.

MADCaP has used mtDNA to classify race based on African contributions, which can be correlated with the slave trade of the 18th century. In the US, a greater contribution of African ancestry is correlated with lower income, less education, and more unemployment. This finding may explain the larger and smaller “heritability” within specific geographies.

Gene-environment interactions and disease outcomes may be a compound way of exploring disparities. One intriguing example is the effects of HNF1B/TCF2 rs4430796 and neighborhood income (Rebbeck 2010) on PSA failure. Homogeneous CC group exhibits high PSA failure in high income populations while TT group exhibits high PSA failure in low income neighborhoods; CT variants are intermediate.

Future Directions
Can Genomics Inform Disparities?


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