Palaeopathology and genes: investigating the genetics of infectious diseases in excavated human skeletal remains and mummies from past populations.

The aim of this paper is to review the use of genetics in palaeomicrobiology, and to highlight the importance of understanding past diseases. Palaeomicrobiology is the study of disease pathogens in skeletal and mummified remains from archaeological contexts. It has revolutionarised our understanding of health in the past by enabling a deeper knowledge of the origins and evolution of many diseases that have shaped us as a species. Bacterial diseases explored include tuberculosis, leprosy, bubonic plague, typhoid, syphilis, endemic and epidemic typhus, trench fever, and Helicobacter pylori. Viral diseases discussed include influenza, hepatitis B, human papilloma virus (HPV), human T-cell lymphotrophic virus (HTLV-1) and human immunodeficiency virus (HIV). Parasitic diseases investigated include malaria, leishmaniasis, Chagas' disease, roundworm, whipworm, pinworm, Chinese liver fluke, fleas and lice. Through a better understanding of disease origins and their evolution, we can place into context how many infectious diseases are changing over time, and so help us estimate how they may change in the future.

Human genetic susceptibility to intracellular pathogens.

Intracellular pathogens contribute to a significant proportion of infectious disease morbidity and mortality worldwide. Increasing evidence points to a major role for host genetics in explaining inter-individual variation in susceptibility to infectious diseases. A number of monogenic disorders predisposing to infectious disease have been reported, including susceptibility to intracellular pathogens in association with mutations in genes of the interleukin-12/interleukin-23/interferon-γ axis. Common genetic variants have also been demonstrated to regulate susceptibility to intracellular infection, for example the CCR5Δ32 polymorphism that modulates human immunodeficiency virus-1 (HIV-1) disease progression. Genome-wide association study approaches are being increasingly utilized to define genetic variants underlying susceptibility to major infectious diseases. This review focuses on the current state-of-the-art in genetics and genomics as pertains to understanding the genetic contribution to human susceptibility to infectious diseases caused by intracellular pathogens such as tuberculosis, leprosy, HIV-1, hepatitis, and malaria, with a particular emphasis on insights from recent genome-wide approaches. The results from these studies implicate common genetic variants in novel molecular pathways involved in human immunity to specific pathogens.