Control of iron metabolism is fundamental to almost all known life. Malaria parasites and other infectious pathogens require iron to grow and multiply, and the human host has evolved to withhold iron from these pathogens using iron-binding and chaperone transport proteins. One such protein is ferroportin, which transports iron from the inside to the outside of a cell. A mutation (Q248H) in ferroportin increases cellular iron export, leading to a 60% decrease in iron within the Q248H cells. The mutation has various outcomes depending on which cells it affects – for example, in red blood cells it might protect from excess toxic iron and haemolytic anaemia, while in enterocytes and macrophages, it might increase iron absorption and recycling.
Since the iron export mutation occurs primarily in populations of African ancestry, it has been hypothesized that the variant has been positively selected due to protection from malaria. However, a recent study conducted by Dr Sarah Atkinson, Senior Lecturer in the Department of Paediatrics and at the KEMRI-Wellcome Trust Research Programme in Kilifi Kenya, shows little evidence to support this claim. The research team used data from 18,320 children from across Africa and 380 pregnant women from The Gambia to determine what are some health impacts of the Q248H mutation. While the iron export mutation may protect from iron deficiency and anaemia, it does not prevent bloodstream bacterial infections. Additionally, there is little evidence that the mutation protects from malaria as it is unlikely to deprive malaria parasites of iron essential for their growth. Finally, Q248H does not appear to be evolutionary selected in African populations due to malaria exposure.
The research, published in Science Advances, is available at: https://advances.sciencemag.org/content/5/9/eaaw0109