November 11, 2005

"Genetic Find Stirs Debate on Race-Based Medicine"

Nicholas Wade writes in the NYT:

In a finding that is likely to sharpen discussion about the merits of race-based medicine, an Icelandic company says it has detected a version of a gene that raises the risk of heart attack in African-Americans by more than 250 percent.

The company, DeCode Genetics, first found the variant gene among Icelanders and then looked for it in three American populations, in Philadelphia, Cleveland and Atlanta.

Among Americans of European ancestry, the variant is quite common, but it causes only a small increase in risk, about 16 percent.

The opposite is true among African-Americans. Only 6 percent of African-Americans have inherited the variant gene, but they are 3.5 times as likely to suffer a heart attack as those who carry the normal version of the gene, a team of DeCode scientists led by Dr. Anna Helgadottir reported in an article released online yesterday by Nature Genetics...

The new variant found by DeCode Genetics is a more active version of a gene that helps govern the body's inflammatory response to infection. Called leukotriene A4 hydrolase, the gene is involved in the synthesis of leukotrienes, agents that maintain a state of inflammation.

Dr. Stefansson said he believed that the more active version of this gene might have risen to prominence in Europeans and Asians because it conferred extra protection against infectious disease.

Along with the protection would have come a higher risk of heart attack because plaques that build up in the walls of the arteries could become inflamed and rupture. But because the active version of the gene started to be favored long ago, Europeans and Asians have had time to develop genetic changes that offset the extra risk of heart attack.

The active version of the inflammatory gene would have passed from Europeans into African-Americans only a few generations ago, too short a time for development of genes that protect against heart attack, Dr. Stefansson suggested.

That's interesting in part because it suggests that interracial marriage could cause health problems by combining genes that haven't evolved together and thus don't work as well together.

I haven't seen much evidence for this incompatibility problem in the past. My assumption has been that minor problems caused by incompatibilities like this were about evened out by small advantages from hybrid vigor, so people born of interbreeding between races were about as healthy as everybody else on average (other than examples of extreme inbreeding such as first cousin marriages).

My published articles are archived at -- Steve Sailer

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