Scientists and researchers at the Oxford University with supported by the KEMRI-Wellcome Trust have jointly compiled a comprehensive map presenting the incidence of the sickle cell gene globally. Global data shows that, the sickle cell gene is predominantly found in regions of high incidences of malaria. This provides ecological support to the supposition that the potentially lethal gene, does not diminish by the process of natural selection by protecting against malaria.

Sickle cell disease, a lethal condition if untreated is generally caused by Hemoglobin S (HbS). The process of natural selection proposes that a gene with predominant disadvantages could be eliminated, but as yet populations in African, The Mediterranean and India exhibit the gene.

Earlier scientists studied and found that the sickle cell gene was predominant in regions of high malaria incidence. This study was propounded as the 'malaria hypothesis'. According to this theory a child inheriting the gene from one parent was protected from malaria, while inheriting the gene from both parents was lethal. This defensive benefit was predominant in regions of high incidence of malaria transmission enabling the gene to endure.

While “malaria hypothesis” has the support of populace and research studies, the unique annotations of an environmental overlap between incidence of sickle cell disease and malaria have not been verified beyond visual comparisons at the large-scale.

The methodology that Dr Fred Piel and colleagues used to look at this scenario was to collate information presently available on the occurrence of the sickle cell gene, particularly in indigenous populations. This data was then geospatially mapped and compared to the intensity and distribution of malaria prior to the malaria control program.

"This study highlights the first steps in our efforts to create an open-access, online database of the frequency of various inherited blood disorders," says Dr Piel, from the University of Oxford. "Such databases will help improving estimates of their public health burden and guide where resources would be best applied."

The malaria hypothesis at the global scale was confirmed by studying the distribution of the sickle cell gene in parts of Africa, India and the Middle East, where the prevalence is high. These areas also exhibit historically high incidences of malaria.

Co-author Dr Simon Hay adds: "The malaria hypothesis is the text-book example of a natural selection 'balancing act', where selection against an unfavorable mutation is weighed against selection in favor of a protective gene.”

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