The world's most famous frozen corpse has had his genome sequenced. An international team has recently published the almost complete DNA sequence of 5,300-year-old Oetzi the Tyrolean Iceman - discovered in the Alps near the Italian-Austrian border in 1991 - and has found clues as to the whereabouts of his closest living relations.
     In 2008, scientists reported the complete sequence of DNA taken from Oetzi's cellular mitochondria. It contained mutations not found in present-day populations, and led to speculation that the iceman had belonged to a people that has vanished from Europe. To get a better picture of Oetzi's ancestry and a look at some of his genetic traits, Albert Zink, head of the Institute for Mummies and the Iceman in Bolzano (Italy) and his team team sequenced the DNA from the nuclei of cells taken from a sliver of the iceman's pelvic bone. The sequence accounts for around 96% of Oetzi's genome.
     The data suggest that Oetzi had brown eyes and type-O blood, and was lactose intolerant. Zink's team also discovered gene variants linked to hardened arteries, which could help to account for calcium deposits found in scans. "He wasn't obese, he was very active, he doesn't have strong risk factors for developing calcification of his heart," says Zink. "Perhaps he developed this due to a genetic predisposition."
     Oetzi's genome also hints at other health problems: Zink's team found almost two-thirds of the genome of Borrelia borgdorferi, a bacterium that causes Lyme disease. Zink found no other telltale signs of Lyme disease in Oetzi's preserved tissues, but he speculates that tattoos on the iceman's spine and ankles and behind his right knee could have been an attempt to treat the joint pain that occurs when the condition goes untreated.
     Zink's team also gathered information about Oetzi's ancestry. His Y chromosome possesses mutations most commonly found among men from Sardinia and Corsica, and his nuclear genome puts his closest present-day relatives in the same area. Perhaps Oetzi's kind once lived across Europe, before dying out or interbreeding with other groups everywhere except on those islands. That makes sense, says Eske Willerslev, a palaeogenomicist at the University of Copenhagen. "Sardinians are a group that people have considered distinct from other Europeans, and in this regard it would be interesting if they were more widely distributed in the past."

Edited from Nature (28 February 2012)