Heart Disease Studies: Is There a Racial Bias Between Blacks and Whites?

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In recent news, two separate studies using genome wide association (GWAS) methods toward identifying genes responsible for cardiovascular heart disease - including genes such as those involved with high blood pressure - have been published in two separate, scientific journals: Nature and PLoS Genetics. The Nature paper’s study involved a tour de force involving genomes from 24 countries of various ethnicities, whereas the PLoS Genetics paper’s study was much smaller and focused on a single ethnic group. The PLoS Genetics paper makes the claim that cardiovascular disease studies typically focus on people of European descent rather than people of African descent who are disproportionately affected by cardiovascular diseases. Which begs the questions, are cardiovascular disease studies race-biased and if so, does it matter when it comes to finding genes that are involved in shared medical conditions such as high blood pressure?

The hottest news in gene discovery is the report by the authors of a paper published in the journal Nature about the shared discovery of 16 new gene regions linked to high blood pressure. The results of their research came from an international collaboration involving hundreds of scientists from 234 institutions based in 24 countries. Data from over 270,000 people was analyzed to find genetic variations that could be linked to blood pressure regulation—an important component of heart disease including hypertension, stroke and hardening of the arteries.

The method of research the scientists used in the published paper is called a “genome wide association” (GWAS) study. A genome wide association study is a large scale genetic approach that involves scanning for specific markers or metaphoric signposts across the genomes of a large sample of people to find genetic variations that may be associated with a particular disease. These markers are typically gene-containing regions that play some role in disease when single nucleotide polymorphisms (SNPs) alter the function of an important protein. These genome wide association studies are particularly useful in uncovering small variations in DNA that are responsible for, or contribute to, common, complex diseases such as high blood pressure and heart disease.

In a similar study published recently in the journal PLoS Genetics, a genome wide association study was performed involving 2,905 African Americans as a follow-up from an Atherosclerosis Risk in Communities (ARIC) study from 19 years ago. Of the 2,905 individuals in the original study, 362 had developed cardiovascular disease, whereas 2,543 were non-afflicted. Their Genome-wide association analysis for incident cardiovascular disease resulted in their discovery of an identified region near the PFTK1 gene as being associated with incident coronary heart disease and subclinical atherosclerosis in African Americans.

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Aside from the results described in the PLoS Genetics paper, another striking message may be evidenced. In at least 3 instances, mention is made toward the importance of this study that other related studies fail to include Africa Americans as research subjects. Rather, that the majority of related studies in cardiovascular disease are focused on research subjects with DNA of European descent.

While documented evidence of racial bias in related fields of medicine where African Americans are known to receive substandard care and medical treatment are well known, and in fact, was recently reported in a study analyzing first-year medical students’ bias toward white patients, do the claims in the PLoS Genetics paper have merit? Or, are the authors merely emphasizing rather heavily that they are the first to do this particular type of study?

In the Nature paper, the authors point out there is evidence of the same common genetic variations in DNA associated with high blood pressure in Europeans as are also frequently found in individuals of Asian and African ancestry. Moreover, the Nature paper study states that their data shows that the genetic effects on blood pressure are broadly similar in people of European, East Asian, South Asian, as well as African ancestries. What remains unclear is how big a role, if any, does differences in gene variation account for differences between ethnic groups with commonly shared diseases such as high blood pressure? In other words, are there black high blood pressure genes and white high blood pressure genes?

Both studies have produced important data that will be used in future studies in attempting to track down specific genetic causes of heart disease and increase our understanding of new and better ways to treat cardiovascular disease. However, if there is a true race bias with respect to identifying race-specific variants of DNA sequence in combating disease, then this is an area of research practice that needs to be addressed as it has been in the practice of medicine and healthcare.

SOURCES:
“Genome-Wide “Association Analysis of Incident Coronary Heart Disease (CHD) in African Americans: A Short Report” (2011) PLoS Genet 7(8): e1002199. doi:10.1371/journal.pgen.1002199
“Genetic variants in novel pathways influence blood pressure and cardiovascular disease risk” Nature (2011) doi:10.1038/nature10405 Published online 11 September 2011
“Association of Unconscious Race and Social Class Bias With Vignette-Based Clinical Assessments by Medical Students” JAMA. 2011; 306(9):942-951. doi: 10.1001/jama.2011.1248

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