Researchers are discovering traces of malarial change in African people

Malaria is an old scourge, but it still leaves its mark on the human genome. And now, researchers have discovered a recent discovery of malaria conversion into human DNA from Cabo Verde, an island country off the coast of Africa.

An island of ten islands in the Atlantic Ocean about 385 miles off the coast of Senegal, Cabo Verde was uninhabited until the mid-1400s, when it was settled by Portuguese sailors who were brought in with them and forced by Africans. work the land.

The Africans brought to Cabo Verde had genetic mutations, which the European colonies did not, which prevents a type of malaria parasite called Plasmodium vivax from invading red blood cells. Among malaria parasites, Plasmodium vivax is the most prevalent, endangering one-third of the world’s population.

People who inherited the defense movement had such a survival advantage that Africans and Europeans intermarried, that the proportion of islanders carrying it had increased, within just 20 generations.

It is thought that other examples of genetic variation in humans have not emerged over tens to hundreds of thousands of years. But malaria development in Cabo Verde took only 500 years.

That is the blink of an eye on the scale of the evolutionary period. “

Iman Hamid, First Author Study and Ph.D. Student, Duke University

Hamid is a Ph.D. Student in Professor Amy Goldberg’s laboratory.

Not surprisingly, a gene that protects against malaria would give an evolutionary edge to humans, which carry it, the researchers said. One of the oldest known diseases, malaria claims up to a million lives each year, most of them children.

The findings, published this month in the journal eLife, representing one of the fastest, most impressive changes measured in the human genome, says a team led by Goldberg and Sandra Beleza of the University of Leicester.

The researchers analyzed DNA from 563 islanders. Using statistical methods they developed for people of mixed ancestry, they compared the island of Santiago, where malaria has always been a fact of life, with other islands of Cabo Verde, where the disease was less common.

The team found that the frequency of defense change on Santiago is higher than expected today, given the sheer number of islanders’ ancestry that can be traced back to Africa against Europe.

In other words, the chances of a person surviving and a family thanks to their genetic code – the strength of the election – were so great that the various protections spread above and beyond the contributions of Africans who reached the shores of Santiago. The same was not true elsewhere in the islands.

The team’s studies also showed that, as the immune mutation spread, nearby pieces of African-like DNA were attached to it, except on Santiago with a malaria plague and not on other Cabo Verdean islands.

Taken together, the findings suggest that their findings were the result of change in the last few years, in the few hundred years since the islands were settled, and not just the bad. publication of long-standing processes in Africa.

Humanity is always evolving, but it has been difficult to evidence recent genetic change – in the last 10 to 100 generations. Part of the problem is that, on such short time intervals, changes in gene frequency will be difficult to detect using traditional statistical methods.

But by using patterns of genetic ancestry to help recreate the history of the Cabo Verdean islanders, the researchers were able to find evolutionary changes that lost methods previously lost.

The authors hope to expand their methods to study other populations where mass migration means that migrants are exposed to different diseases and environments than before.

“People are still coming forward, and here we have evidence,” Hamid said.