The conquistadors are known for bringing smallpox and measles to the New World. Researchers discovered they brought something else: a gene mutation for early-onset Alzheimer’s disease.
Yarumal, Colombia, has the highest per capita rate of people with Alzheimer’s disease, sometimes called Yarumal's curse. In the state of Antioquia, which includes the city Yarumal, an estimated 5,000 people carry the gene mutation. Half of those people will be diagnosed by age 45, and the other half will develop the disease by the time they are 65.
Much research has been done on the residents of Yarumal but no one has researched how the mutation first appeared. Until now.
Ken Kosik, co-director at the University of California at Santa Barbara’s Neuroscience Research Institute and a professor in the Department of Molecular, Cellular and Developmental Biology, led a group that collected blood samples and sequenced their genomes. The mutation that causes Yarumal’s form of Alzheimer’s, E280A, was found in 74 of 102 participants.
Kosik’s team was also able to conduct an identity-by-descent analysis to determine how the people in the study were related. The analysis suggested the mutation arose from a conquistador around 375 years ago. The initial mutation has been traced to 17th century Spain.
“It’s hard to explain why all these people would share such a large chunk of DNA if there hadn’t been a common founder,” Kosik says to The Washington Post.