Sex with Denisovans a double-edged sword?

Controversy continues as to whether or not archaic Homo populations contributed to modern human DNA, and if so, whether said DNA is functional. This summer, a large research project led primarily from Stanford suggested that hybridization with archaic populations resulted in the HLA gene repertoire we see today in modern populations, a crucial tool of the immune system used to recognize pathogens.

However there may have been a downside to the Neanderthal flings. High variability in immunity genes may be linked to autoimmune disorders, wherein the immune system turns on itself. In particular, the group are looking at the gene variant HLA-B51, which is thought to have been inherited from Neanderthals, and which has been shown to be linked to the inflammatory disorder Behcet's disease.