A comparison of Neanderthal DNA with the genomes of present-day patients has pointed up connections between our now-extinct cousins and modern traits ranging from addiction and depression to blood clotting and skin problems.
“Our main finding is that Neanderthal DNA does influence clinical traits in modern humans,” Vanderbilt University geneticist John Capra, the senior author of a paper published today by the journal Science, said in a news release.
The comparison drew upon a database that links biological samples from 28,000 patients with anonymized versions of their electronic health records. The Electronic Medical Records and Genomics Network, also known as eMERGE, is funded by the National Human Genome Research Institute. The network draws upon records from nine hospital systems across the country, including Vanderbilt University Medical Center as well as Group Health Cooperative / University of Washington Medical Center / Fred Hutchinson Cancer Research Center in Seattle.
Geneticists determined years ago that Neanderthals and modern humans interbred, and that most modern-day Eurasians have roughly 1 to 4 percent Neanderthal DNA in their genomes. But they’ve only recently started making associations between Neanderthal snippets of genetic code and their functional roles. Here are a few of the linkages reported in the Science paper:
- A specific bit of Neanderthal DNA is linked with a significant increase in the risk of nicotine addiction.
- Other variants are associated with the risk of depression – some positively, some negatively. The researchers said they were surprised to discover how many snippets were associated with psychiatric and neurological effects.
- One Neanderthal variant appears to increase blood coagulation. That may have helped early humans during their migrations, by closing up wounds more quickly and preventing new pathogens from entering the blood stream. But now the variant has a detrimental effect, raising the risk for stroke, pulmonary embolism and pregnancy complications, the researcher said.
- The study also confirmed that Neanderthal DNA affects cells called keratinocytes, which play a role in skin color and hair. Scientists have previously suggested that Neanderthals passed down genetic variants that helped modern humans adapt to a colder, less sunny climate after their migration out of Africa. However, the new study shows that Neanderthal variants also influence the risk of developing sun-induced skin lesions.
The Science study focused on clinical traits that were covered in physicians’ billing codes, but Capra says he is now working on an analysis that includes other information in the medical records, such as lab results, doctors’ notes and medical images.
The principal author of the Science paper, “The Phenotypic Legacy of Admixture Between Modern Humans and Neanderthals,” is Vanderbilt doctoral student Corinne Simonti.