A possible explanation of the high frequency of BAFF-var is its positive selection due to a selective pressure acting in Sardinia and, in general, in Southern Europe. The most plausible candidate is malaria infection, as suggested by the correlation between the frequency of this variant vs malaria prevalence across Europe before its eradication (~1950).112 Additionally, BAFF transgenic mice survived lethal Plasmodium yoelii malaria, and there is evidence that the malaria parasite can prevent long-term immunity dysregulating the dendritic cells producing BAFF.113
