It turns out that many people of northern European descent have inherited some Neanderthal genes. A study found that these are contributing to a higher risk for Dupuytren's contracture (also called Dupuytren's disease). One study estimated that about 30% of Norwegian males over the age of 60 have Dupuytren's disease, but studies find that it is rare in African populations.
The researchers of the study looking at Dupuytren's disease noted that the average Neanderthal ancestry among Europeans is about 2%. [Note: Neanderthals are also referred to as Neandertals.]
Dupuytren's disease is a gradual thickening and tightening of tissue under the skin in the hand, which eventually can cause one or more fingers to stay bent toward the palm. It usually occurs in men over the age of 60.
Neanderthals and Denisovans (referred to as “archaic humans”) are now extinct. They lived in Western (Neanderthals) and Eastern Eurasia (Denisovans) until approximately ∼42,000 years ago. There was interbreeding (sex) with modern humans (Homo sapiens), which is how some of their genes have been passed down through the years.
From Science Daily: The Viking disease can be due to gene variants inherited from Neanderthals
Many men in northern Europe over the age of 60 suffer from the so-called Viking disease, which means that the fingers lock in a bent position. Now researchers at Karolinska Institutet, together with colleagues, have used data from over 7,000 affected individuals to look for genetic risk factors for the disease. The findings, which have been published in Molecular Biology and Evolution, show that three of the strongest risk factors are inherited from Neanderthals.
Up to 30 percent of men in northern Europe over 60 suffer from a condition called Dupuytren's contracture. The condition is sometimes called the Viking disease because it mainly affects individuals with northern European ancestry. The disease is significantly more common in men than women and usually begins as a lump in the palm of the hand that grows and causes one or more fingers to lock in a bent position. The condition is usually not painful, but the nodules may sometimes be tender to pressure.
The researchers in the study, led by Hugo Zeberg from Karolinska Institutet and Svante Pääbo from Max Planck Institute for Evolutionary Anthropology, set out to investigate whether genetic variants inherited from Neanderthals are involved in the disease.
Neanderthals lived in Europe and western Asia until about 40,000 years ago, when they were replaced by modern humans. However before Neanderthals disappeared, they mixed with modern humans. As a result, between one and two percent of the genomes of people with roots outside of Africa come from Neanderthals.
"Since Dupuytren's contracture is rarely seen in individuals of African descent, we wondered whether gene variants from Neanderthals can partly explain why people outside of Africa are affected," says Hugo Zeberg, assistant professor at the department of Physiology and Pharmacology, Karolinska Institutet.
The researchers used data from three large clinical cohorts in the US, UK, and Finland, which allowed them to compare the genomes of 7,871 sufferers and 645,880 healthy controls. They identified 61 genetic risk factors for Dupuytren's contracture. The researchers found that three of these were inherited from Neanderthals, and these included the second and third most important risk factors.
The study is further evidence that the intermingling between Neanderthals and our ancestors has important consequences for the prevalence of some diseases, particularly among certain groups.