Search terms included combinations of “susceptibility”, “genetic susceptibility”, “heritability”, “twin”, “genetic”, “genetic epidemiology”, “infection”, “infectious diseases”, as well as terms for specific infections (eg, “malaria”) and genes and gene products (eg, “mannose binding lectin”): eg, PubMed search term: “HIV AND polymorphism NOT drug”; field: text word; limits: humans. Here, MBL2 is linked to infection.