February 29, 2012
Earliest Case Of Lyme Disease Discovered In 5,300 Year-old ‘Iceman’
Scientists have sequenced the full genome of “Oetzi the Iceman", a 5,300-year-old body discovered frozen in the Eastern Alps in 1991, and determined he had brown eyes, was lactose intolerant, had blood type “O” and was predisposed to cardiovascular disease.
The international team of researchers also found genetic material from the bacterium that causes Lyme disease, making Oetzi the earliest documented case of the infection.
“Sequences corresponding to ~60% of the genome of Borrelia burgdorferi are indicative of the earliest human case of infection with the pathogen for Lyme borreliosis,” the researchers said.
The international team of scientists also found clues pointing to the whereabouts of Iceman´s closest living relations.
To sequence Oetzi´s genome, the researchers obtained a sample from his hipbone, and searched for human DNA and that of other organisms.
Although they found evidence of other microbes, Borrelia burgdorferi was the only one known to cause disease, said Albert Zink, a study researcher and head of the European Institute for Mummies and the Iceman at the European Academy of Bozen/Bolzano in Italy.
"Our data point to the earliest documented case of a B. burgdorferi infection in mankind. To our knowledge, no other case report about borreliosis [Lyme disease] is available for ancient or historic specimens," wrote Zink and colleagues in a paper published February 28 in the journal Nature Communications.
Lyme disease, which is transmitted by ticks in North America and Eurasia, was first identified in the United States in Connecticut in the mid-1970s.
Previous research had examined genetic material within the Iceman's mitochondria -- the energy-producing centers in cells that are inherited through the maternal line. However, the analysis failed to reveal any living relatives.
In the current study, researchers decoded the DNA within the nuclei of the Oetzi´s cells, which is inherited from both parents. They determined that the roughly 45-year-old Iceman belonged to a lineage that, while rare, is still present in some places.
"This means his ancestors came from Europe originally from the East and spread over most or part of Europe," Zink said.
"This original population was somehow replaced by other populations, but they remained quite stable in remote areas like Sardinia and Corsica."
The genetic analysis also suggests that the Iceman was lactose intolerant, something Zink said was not surprising since people were only beginning to settle down and become farmers during the time Oetzi lived.
The researchers also found that Iceman had a genetic predisposition for heart disease, something that supported previous scans showing a buildup of deposits within his arteries.
Despite the health problems afflicting Iceman, he appears to have died a violent death. The researchers believe Oetzi was likely killed by a flint arrowhead shot into his left shoulder.
The study was published February 28 in the journal Nature Communications.
Image Caption: Ãtzi the Iceman, a well-preserved natural mummy of a Chalcolithic (Copper Age) man from about 3300 BC, who was found in 1991 in the Schnalstal glacier in the Ãtztal Alps, near Hauslabjoch on the border between Austria and Italy. Credit: © South Tyrol Museum of Archaeology
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