PHILADELPHIA For tens of thousands of years, the genomes of malaria parasites and humans have been at war with one another. Now, University of Pennsylvania geneticists, in collaboration with an international team of scientists, have developed a new picture of one way that the human genome has fought back.
The international team was led by Sarah Tishkoff, a Penn Integrates Knowledge professor with appointments in the genetics department in Penn's Perelman School of Medicine and the biology department of biology in the School of Arts and Sciences, and Wen-Ya Ko, a postdoctoral fellow in the genetics department at the medical school. They performed a genetic analysis of 15 ethnic groups across Africa, looking for gene variants that could explain differing local susceptibility to malaria.
Their research will be published online in the journal American Journal of Human Genetics on June 2.
Malaria remains one of the deadliest diseases on the planet, annually killing about a million people, 90% of whom live in Africa. Different populations show different responses to the parasites that cause malaria; the team conducted the largest cross-population comparison ever on a pair of genes related to malaria's ability to enter red blood cells.
"When you try to identify the variants that are associated with disease susceptibility, it's important to do a very fine scale study," Ko said. "Different populations evolve independently, to a certain degree, so different populations can come up with unique mutations."
The life cycle of malaria depends on infecting red blood cells by binding to their surfaces, which is why mutations, such as sickle cell anemia, that change the overall shape of those cells are thought to have experienced positive selection.
"Both host and the parasite try to fight back with mutations; it's a co-evolution arms-race that leaves a signature of selection on the genes," Ko said. "We've ide
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University of Pennsylvania