A report from the Karolinska Institute in Sweden has linked the development of Dupytren’s contracture to genes acquired from Neanderthal man. Dupytren’s contracture represents an abnormal thickening of fascia on the palm of the hand. It generally affects the ring and little fingers and may eventually create a thick cord that pull the fingers into a bent position. The condition is more common in men than women and tends to run in families. The disease is predominantly one of men in Northern Europe and those with European ancestry.
Researchers have used data from over 7000 affected individuals in the hope of finding genetic risk factors. In the paper by Agren et al (and published this month in Molecular Biology and Evolution) three of the strongest genetic links appear traceable back to Neanderthal man. In all 61 genetic risk factors were identified. Of the three with the strongest links at least two were linked to Neanderthal man. One of these represents a chromosome 7 linked locus relating to a splicing variant of EPDR1. EPDR1 is a lysosomal protein in which an alternative splicing caused by the Neanderthal haplotype results in a disrupted lipid binding site. Significantly EPDR1 is linked to myofibroblast contractility.
Today’s human population are the direct descendants of the genus Homo sapiens. But there were originally two other closely related human populations - the Denisovans and the Neanderthals (Homo neanderthalensis). It appears that modern human lineage and that of Neanderthals separated at least 500,000 years ago. Neanderthals evolved in Europe and Asia whilst Homo sapiens were evolving in Africa. Neanderthals were extremely adaptable and able to flourish in the cold environments of Siberia as well as the temperate climates of Spain. Neanderthals became extinct about 40,000 years ago for reasons which remain unclear.
Prior to that there was an overlap between the groups that went on to represent modern man (Homo sapiens) as well as the Neanderthal and Denisovan populations – and this included interbreeding. It explains why approximately 1-2% of our DNA is derived from Neanderthal man. This interaction (which was probably around 100,000 years ago) explains the current demographic distribution of Dupytren’s contracture. Those Homo sapiens who remained in Africa rather than venturing towards the Neanderthal dominated European and Asian continents were less likely to have interbred. As a result those of modern African descent have virtually no Neanderthal genes and a similarly very low incidence of Dupytren’s contracture.
