A genetic study in an extremely remote community in the South Pacific island nation of Papua New Guinea has shed new light on a brain disease.The disease is spread by people eating their dead relatives and caused thousands of deaths in the 20th century.On March 19, the results were published in the American Journal of Human Genetics.
The eastern highlands of Papua New Guinea are isolated from the world by mountains, canyons and fast-flowing rivers, and it wasn't until the early 20th century that outsiders realized it was inhabited by about a million people.
There, some tribes popularized a cannibalistic custom known as a "funeral feast" in which the bodies of deceased relatives were eaten as part of funeral ceremonies.
Sometimes, this means they ingest abnormally folded proteins called prions, which cause a deadly neurodegenerative disease called kuru's disease, which is associated with Creutzfeldt-Jakob disease.At least 2,700 people in Papua New Guinea's eastern highlands have died from Kulu disease.
Simon Mead and colleagues at University College London examined the genomes of 943 people from the region, representing 68 villages and 21 linguistic groups.The researchers said that although the area of Papua New Guinea is only about 11,000 square kilometers, the genetic differences between different populations are as large as those of Finns and Spaniards who are 3,000 kilometers apart.
The study found that not all people who attended the "funeral feast" died of the disease.Mead and colleagues say it appears that this regional group has begun to evolve some resistance to Kulu disease, which causes tremors, loss of coordination, and ultimately death.
The study found that some older women who survived carried genetic variants that encode prion proteins, which may have made them resistant to kuru disease.
In the 1950s, with the abolition of the "funeral feast" custom, the prevalence of Kulu disease began to subside, but in some villages, the number of women has decreased because too many people have died from Kulu disease.Mead says women and children are probably most vulnerable to the disease because they eat the brains of their deceased loved ones.
However, genetic evidence suggests that despite concerns about the disease, large numbers of women are still pouring into the region, especially in areas with the highest incidence of Kulu disease.
Mead said the team wanted to understand what gave people resistance to prion diseases like Creutzfeldt-Jakob disease, which caused a major epidemic in the UK in the 1990s.
"Our work examines genetic factors that may help local people fight off Kulu disease."This resistance gene may suggest therapeutic targets."”
Ira Deveson of the Gavin Medical Institute in Sydney, Australia, said the study provided new insights into the "rich and unique cultural, linguistic and genomic diversity" of the Eastern Highlands. "This demonstrates that genomics can be used to look back—to understand the genetic characteristics of past pandemics and to understand how these characteristics shape today's population."