A large team of scientists led by Vanderbilt University geneticist John Capra has found surprising correlations between Neanderthal-derived DNA and disease states in humans.

Previous studies have suggested that when populations of anatomically modern humans migrated out of Africa, they interbred with Neanderthals (Homo neanderthalensis).

More recently, genetic researchers have identified parts of the human genome carrying Neanderthal genetic variants, but they still don’t fully understand how Neanderthal-derived variants influence modern human traits.

Now, by comparing a genome-wide map of Neanderthal gene groups with health records of 28,000 adults of European ancestry, Dr. Capra and co-authors have documented the lingering effects of Neanderthal-derived versions of genes.

The data came from the Electronic Medical Records and Genomics Network (eMERGE), which links digitized records from Vanderbilt University Medical Center’s BioVU databank and eight other hospitals around the United States.

“Our main finding is that Neanderthal DNA does influence clinical traits in modern humans,” said Dr. Capra, who is the senior author on a study published in the journal Science.

“We discovered associations between Neanderthal DNA and a wide range of traits, including immunological, dermatological, neurological, psychiatric and reproductive diseases.”

The team first defined about 135,000 high-confidence Neanderthal genetic variations in modern humans.

Next, they looked at the relationships between these genetic variations and conditions Neanderthal-derived alleles are thought to influence, ultimately finding that Neanderthal alleles were significantly correlated with the risk for 12 traits, including depression, myocardial infarction, and blood disorders.

For example, the team found that a specific bit of Neanderthal DNA significantly increases risk for nicotine addiction.

They also found a number of variants that influence the risk for depression: some positively and some negatively. In fact, a surprisingly number of snippets of Neanderthal DNA were associated with psychiatric and neurological effects.

“The pattern of associations that we discovered suggest that today’s population retains Neanderthal DNA that may have provided modern humans with adaptive advantages 40,000 years ago as they migrated into new non-African environments with different pathogens and levels of sun exposure,” the scientists said.

“However, many of these traits may no longer be advantageous in modern environments.”

_____

Corinne N. Simonti et al. 2016. The phenotypic legacy of admixture between modern humans and Neandertals. Science, vol. 351, no. 6274, pp. 737-741; doi: 10.1126/science.aad2149