Map supports sickle cell link

Science | Health 03 Nov 10 At a global scale, the sickle cell gene is most commonly found in areas with historically high levels of malaria, adding geographical support to the hypothesis that the gene, whilst potentially deadly, avoids disappearing through natural selection by providing protection against malaria. In a study funded by the Wellcome Trust, geographers, biologists and statisticians at the University of Oxford, together with colleagues from the KEMRI-Wellcome Trust Programme in Kenya, have produced the first detailed global map showing the distribution of the sickle cell gene. The results are published today in open access . Haemoglobin S ( HbS ) is known to cause sickle cell disease, which is usually fatal if untreated. Natural selection suggests that such a disadvantageous gene should not survive, yet it is common in people of African, Mediterranean and Indian origin.More than sixty years ago, researchers observed that the sickle cell gene tended to be more common in populations living in, or originating from, areas of high malaria prevalence. This led to the 'malaria hypothesis', which suggested that, although deadly when inherited from both parents, the gene provided a degree of protection from malaria in children inheriting it from just one parent. This protective advantage was strong enough in areas of intense malaria transmission for the gene to survive.