25 July 2011
ByAppeared in BioNews 617
Ethnic and racial minorities are in danger of missing out on future medical advances - based on genetic research – because they are under-represented in basic studies, says a review published in Nature Genetics by a team of geneticists from Stanford University and University of California, San Francisco.
'Geneticists worldwide must investigate a much broader ensemble of populations, including racial and ethnic minorities', said Professor Carlos Bustamante of Stanford University, who co-authored the paper. 'If we do not, a biased picture will emerge of which variants are important, and genomic medicine will largely benefit a privileged few'.
The paper argues that a Euro-centric approach to genetic research has led to a neglect of the rare genetic diseases particular to ethnic and racial minorities. In order to understand these rare diseases, researchers need to trace the origin of genetic variants that originated within, and are specific to, particular populations.
The review follows a 2009 paper which found that 96 percent of all genome-wide association studies (GWAS) were carried out on people of European ancestry. GWAS are said to be the gold standard for genetic research. The entire genome of an individual is sequenced and compared to hundreds or thousands of others to check for differences in DNA and researchers hoped that GWAS would help them understand how genetic diseases are passed on from one generation to another.
Previously it was thought that inherited diseases are due to genetic variants that are commonly held across different populations. This would mean that findings in one population could be generalised to others. Now, however, it is understood that the genetic basis of many rare, inherited diseases, is itself due to rare genetic mutations shared by people of a particular ethnic origin.
A recent analysis of how genetic variation differs by ethnic groups showed that genetic variants relevant to disease are often specific to one population, and so may not show up in the genomes of another. For example, genetic variants linked to diabetes risk in Europeans do not appear in other populations.
The problem that Professor Bustamante and colleagues point out in their review is that since only four percent of GWAS studies to date include individuals of non-European ancestry, their genomes are simply not being adequately represented in genomic research.
Yet the implications are especially strong for those with rare genetic diseases that are found only within a particular ethnic minority. As Professor Bustamante says, with the ever-reducing costs of sequencing the full genome, this exclusivity can no longer continue. He cautions that if genetic research does not adequately represent the diversity of groups that makes up the human population, 'a biased picture will emerge of which variants are important, and genomic medicine will largely benefit a privileged few'.