A
new study conducted by researchers at Duke University suggests that the
gene that influences vulnerability to heart disease has been influenced
by the pressure of natural selection that in turn has influenced heart
disease risk. The researchers, led by Gregory Wray and Matthew
Rockman explored the evolutionary history of one particular variant in
a gene called MMP3. MMP3 protein is an enzyme that plays a role
in regulating the elasticity and thickness of blood vessels and the
variant they studied tends to retard the progress of coronary artery
heart disease. They first compared the structure of the gene
region among non-human primates -- including the chimpanzee, gorilla,
orangutan and baboon. It revealed that that the region of the gene is
rapidly evolving and had been a "hotspot" of mutation for tens of
millions of years. Then they compared the variation in the
regulatory region of the MMP3 gene among seven populations from around
the world --Cameroon, China, England, Ethiopia, India, Southern Italy
and Papua New Guinea. The pattern of variation was compared with
the random genetic variation taking place in a group of neutral genetic
markers which revealed that the variation in the gene among populations
could be attributed to evolutionary positive selection. The
analyses of data on the genetic variation among the sample of British
middle-aged men indicated that the men would have suffered 43 percent
more heart attacks had the positive selection for the gene variant not
occurred. "We really don't know why this selection occurred,
because this gene is involved in so many different processes. Because
heart disease is a relatively recent disease, it's more likely that the
selection was for some other function of MMP3, and the heart disease
effect was incidental," Rockman said. |
