Racial Disparities in Cardiovascular Disease Not Explained by Genome Studies

Jay S. Kaufman, Ph.D Canada Research Chair in Health Disparities Department of Epidemiology, Biostatistics, and Occupational Health McGill University Montreal, Quebec CANADAMedicalResearch.com Interview with:
Jay S. Kaufman, Ph.D

Canada Research Chair in Health Disparities
Department of Epidemiology, Biostatistics, and Occupational Health
McGill University
Montreal, Quebec Canada

Medical Research: What is the background for this study? What are the main findings?

Response: Published scientific articles speculate frequently about genetic predispositions in different racial groups as explanations for observed disease disparities.  They infer this from the higher rates observed in racial minorities, even after adjusting for some social and behavioral measures.  Taking the example of the racial disparity between blacks and whites in cardiovascular diseases (stroke, heart attack, heart failure, hypertension, etc), ours is the first published study to review all of the existing results from GWAS (genome-wide association studies) to see if they provide any support for this commonly stated position.  To date, they do not.  We performed an electronic literature search through the PubMed database to identify review articles and meta-analyses related to genetic risk factors for cardiovascular disease in samples that included populations of European and African ancestries. We focused our search on the 7-year period from January 1, 2007 to January 1, 2014, which corresponded to the rapid proliferation of large pooled GWAS activity. This search strategy yielded 197 review articles or meta-analyses.  68 of these articles contained relevant data, but very few reported significant associations in both racial groups, with just 3 variants meeting study-specific significance criteria. For most outcomes, there were too few estimates for quantitative summarization, but when summarization was possible, racial group did not contribute to heterogeneity. Most associations reported from genome-wide searches were small, difficult to replicate, and in no consistent direction that favored one racial group or another.

Medical Research: What should clinicians and patients take away from your report?

Response: The first genome-wide association study (GWAS) was published about a decade ago, and more than 1,700 have now been conducted, cataloging over 4,000 single nucleotide polymorphisms (SNPs) in relation to over 200 diseases. It was reported in 2008 that worldwide spending on genomic research was approximately $3 billion per year, with approximately $1 billion annually from the United States.  It was an early promise that this investment would lead us to the answers for important population disease patterns, such as the excess of cardiovascular disease in people of African origin living in the Western Hemisphere.   Although the substantial investment in this technology might have produced clinical advances, it has thus far made little or no contribution to our understanding of population-level racial health disparities in cardiovascular disease.

Medical Research: What recommendations do you have for future research as a result of this study?

Response: We examined only populations of African origin and populations or European origin.  A logical extension would be to consider East Asian and Native American populations as well, although the number of existing studies may be even smaller.

One could also extend this kind of analysis to other important health outcomes, especially cancers and diabetes.

The obvious implication of this “dead-end” for GWAS studies to date is to change the focus away from seeking explanations in single nucleotide polymorphisms (SNPs) and other simple genetic variations.  If one wants to pursue genetic research, it may be necessary to look to some kind of interactions between genes and environments.  But the accumulated data on these kinds of interactions is so far even more sparse, and the existing methods even more limited at this point in time.

The obvious alternative to this genetic paradigm, which so far has been unsuccessful at explaining racial disparities in cardiovascular disease mortality at the population level, would be to look to social and environmental factors, such as environmental contaminants, diet, obesity, and psychosocial stress.

Funding for this study was provided by the Canada Research Chairs Program.

Citation:

The Contribution of Genomic Research to Explaining Racial Disparities in Cardiovascular Disease: A Systematic Review.

Kaufman JS, Dolman L, Rushani D, Cooper RS.
Am J Epidemiol. 2015 Mar 1. pii: kwu319. [Epub ahead of print]
PMID: 25731887

 

MedicalResearch.com Interview with:, & Jay S. Kaufman, Ph.D (2015). Racial Disparities in Cardiovascular Disease Not Explained by Genome Studies MedicalResearch.com