Human intergroup variation and disease genetics

Wide genome analyses of vast population samples permitted by rapid technological progress (high-throughput whole-genome sequencing) have revealed or confirmed the genetic command of many Mendelian and common diseases. These studies have supported the view that genes related to diseases are unevenly distributed around the world and tend to be geographically localized, as a result of different selective pressures acting on human populations following the out-of-Africa migrations. In disease genetics studies, group comparisons are especially relevant for preventive medicine, when general policies have to be defined. In many cases, major continental groupings are overly broad units for the analysis of disease gene distribution, since smaller groups may exhibit strong specificities in this matter. Genomics makes it possible to rule out the hypothesis that environment plays an overdominant role in the etiology of complex diseases, although environmental parameters obviously should be carefully taken into account in individual diagnosis and preventive medicine. Uneven geographical distribution is especially notable in genes linked to defense against transmissible diseases and to autoimmune disorders as a result of specific pathogen pressures in different geographical localities