Fascia, the fibrous connective tissue that literally holds the body together, is one of the unsung heroes of human anatomy. The stringy, white substance – which is basically sheets of connective tissue held together with collagen – cinches together your muscles and organs so they can act as a unified whole.
On the palms of your hands, fascia has an important job, which is to create a rugged surface suitable for gripping. Without it, skin would slide around over bones, muscles and blood vessels, making it difficult, if not painful, to hold onto anything.
The palmar fascia enables an important part of human life, but it can limit life, as well. In the case of Dupuytren’s disease, the fascia slowly thickens and contracts, forming nodules and eventually cords of tissue that pull the fingers inward, trapping them. And in a recent scientific study, we may now know where the disease came from.
What Is Dupuytren's Disease?
According to the new genetic analysis performed at Karolinska Institutet in Sweden, Neanderthal DNA is partly to blame for Dupuytren’s, which is genetically inheritable.
The condition most commonly affects the ring and middle fingers, which extend from the center of the palmar fascia, curling them back towards the palm. In severe cases, surgery can improve the range of motion but may not be able to restore it completely.
Scientists have identified a long list of risk factors for Dupuytren’s: Men are more likely to develop it than women, and the condition affects not just people of northern European descent but also Scandinavians. Certain medical conditions, including diabetes and seizure disorders, increase one’s risk as well, as does old age.
Who Can Inherit Dupuytren's Disease?
The study drew on genomes from 7,871 people who had Dupuytren’s and found 61 genes related to the disease, including three that had come from the Neanderthals. Of those, two stood out as the second and third most important for predicting Dupuytren’s.
Early Homo sapiens mated with both Neanderthals and Denisovans, another extinct species, and the evidence remains in portions of our collective DNA, with some major exceptions. People from Sub-Saharan Africa contain little influence from Neanderthals, while genes from elsewhere contains about 2 percent passed down from the species.
The disease is most common in Northern Europe, where more Neanderthal influence is evident. One study that tracked Dupuytren’s over 60 years estimated that as many as 30 percent of Norwegians develop it over their lifetime.
“This is a case where the meeting with Neanderthals has affected who suffers from illness,” says the paper’s lead author, Hugo Zeberg in a press release, “although we should not exaggerate the connection between Neanderthals and Vikings.”
Read More: How Much Neanderthal DNA do Humans Have?