Malaria continues to select for sickle cell trait in Central Africa

Abstract

Sickle cell disease (SCD) is a genetic disorder that poses a serious health threat in tropical Africa, which the World Health Organization has declared a public health priority. Its persistence in human populations has been attributed to the resistance it provides to Plasmodium falciparum malaria in its heterozygous state, called sickle cell trait (SCT). Because of migration, SCT is becoming common outside tropical countries: It is now the most important genetic disorder in France, affecting one birth for every 2,400, and one of the most common in the United States. We assess the strength of the association between SCT and malaria, using current data for both SCT and malaria infections. A total of 3,959 blood samples from 195 villages distributed over the entire Republic of Gabon were analyzed. Hemoglobin variants were identified by using HPLCy (HPLC). Infections by three species of Plasmodium were detected by PCR followed by sequencing of a 201-bp fragment of cytochrome b. An increase of 10% in P. falciparum malaria prevalence is associated with an increase by 4.3% of SCT carriers. An increase of 10 y of age is associated with an increase by 5.5% of SCT carriers. Sex is not associated with SCT. These strong associations show that malaria remains a selective factor in current human populations, despite the progress of medicine and the actions undertaken to fight this disease. Our results provide evidence that evolution is still present in humans, although this is sometimes questioned by scientific, political, or religious personalities.sickle cell disease | Plasmodium falciparum | human evolution | Gabon | natural selection

Disease resistance through impairment of α-SNAP–NSF interaction and vesicular trafficking by soybean Rhg1

“…Resistance to pathogens through compromises in essential gene function, partially analogous to Rhg1, has also been reported in humans. For example, resistance to malaria, and possibly typhoid fever, may be enhanced by specific mutations in hemoglobin or cystic fibrosis transmembrane conductance receptor, respectively (38,39). However, individuals homozygous for these alleles are afflicted with sickle cell anemia or cystic fibrosis.…”

Sickle Cell Disease

“…4 Although the exact role of several mechanisms of protection that have been identified is still being debated, the "malaria hypothesis" formulated by Haldane in 1949 and by Allison in 1954 is a textbook example of natural selection and balanced polymorphism, a process that is ongoing. 5 Because of slave trading and contemporary population movements, the distribution of sickle cell disease has spread far beyond its origins. 6 Population estimates in the United States suggest that a total of approximately 100,000 persons have the disease.…”

Storage related haematological and biochemical changes in Plasmodium falciparum infected and sickle cell trait donor blood

“…Liberia, Ghana and Uganda have 10–15% of their population being carriers of haemoglobin S gene [13, 15, 16]. Cameroon and Gabon have haemoglobin S gene prevalence of 19 and 22%, respectively [17, 18]. SCT individuals are clinically healthy to donate blood [19].…”