The Role of Selection and Migration in the Evolution of (Auto)Immunity Genes

Abstract

The genetic architecture of multiple sclerosis is complicated. Additionally, the disease incidence varies per population or per geographical region. A recent study gives convincing explanations about the north-south incidence gradient of multiple sclerosis in Europe, by analyzing ancient and modern human genomes. Interestingly, the evidence shows that multiple sclerosis associated immunogenetic variants underwent positive selection in Asian and European populations. Lifestyle and pathogen infections probably shaped the overall multiple sclerosis risk. These results complete the findings of previous studies that showed that a high percentage of the autoimmunity associated genetic variants are under selection pressure.

Keywords: Adaptation; Antagonistic pleiotropy; Autoimmune disease; Evolutionary medicine; Migration; Mutation.

Fig. 1

Fu and Li's D values for the 1000 Genomes Project populations (populations codes are found below), in a candidate genetic region under selection found in the HLA region of chromosome 6 (see text for details). Values that significantly deviate from zero are informative about distinct demographic and/or selective events (Fu and Li 1993). The Finnish population displays the highest value. The graph has been created by the PopHumanScan database (Murga-Moreno et al. 2019). East Asia: CHB: Han Chinese, JPT: Japanese, CHS: Southern Han Chinese, CDX: Dai Chinese, KHV: Kinh Vietnamese. Europe: CEU: Utah residents with Northern and Western European ancestry, TSI: Tuscan, GBR: British, FIN: Finnish, IBS: Spanish. Africa: YRI: Yoruba in Nigeria, LWK: Luhya in Kenya, GWD: Gambian, MSL: Mende in Sierra Leone, ESN: Esan in Nigeria, ASW: African-American, ACB: African-Caribbean. South Asia: GIH: Gujarati Indian in Houston, PJL: Punjabi in Pakistan, BEB: Bengali in Bangladesh, STU: Sri Lankan, ITU: Indian