TY - JOUR
T1 - α+-thalassemia protects African children from severe malaria
AU - Mockenhaupt, Frank P.
AU - Ehrhardt, Stephan
AU - Gellert, Sabine
AU - Otchwemah, Rowland N.
AU - Dietz, Ekkehart
AU - Anemana, Sylvester D.
AU - Bienzle, Ulrich
PY - 2004/10/1
Y1 - 2004/10/1
N2 - The high frequency of α+-thalassemia in malaria-endemic regions may reflect natural selection due to protection from potentially fatal severe malaria. In Africa, bearing 90% of global malaria morbidity and mortality, this has not yet been observed. We tested this hypothesis in an unmatched case-control study among 301 Ghanaian children with severe malaria and 2107 controls (62% parasitemic). In control children, α+- thalassemia affected neither prevalence nor density of Plasmodium falciparum. However, heterozygous α+-thalassemia was observed in 32.6% of controls but in only 26.2% of cases (odds ratio [OR], 0.74; 95% confidence interval [CI], 0.56-0.98). Protection against severe malaria was found to be pronounced comparing severe malaria patients with parasitemic controls (adjusted OR in children < 5 years of age, 0.52; 95% CI, 0.34-0.78) and to wane with age. No protective effect was discernible for homozygous children. Our findings provide evidence for natural selection of α+-thalassemia in Africa due to protection from severe malaria.
AB - The high frequency of α+-thalassemia in malaria-endemic regions may reflect natural selection due to protection from potentially fatal severe malaria. In Africa, bearing 90% of global malaria morbidity and mortality, this has not yet been observed. We tested this hypothesis in an unmatched case-control study among 301 Ghanaian children with severe malaria and 2107 controls (62% parasitemic). In control children, α+- thalassemia affected neither prevalence nor density of Plasmodium falciparum. However, heterozygous α+-thalassemia was observed in 32.6% of controls but in only 26.2% of cases (odds ratio [OR], 0.74; 95% confidence interval [CI], 0.56-0.98). Protection against severe malaria was found to be pronounced comparing severe malaria patients with parasitemic controls (adjusted OR in children < 5 years of age, 0.52; 95% CI, 0.34-0.78) and to wane with age. No protective effect was discernible for homozygous children. Our findings provide evidence for natural selection of α+-thalassemia in Africa due to protection from severe malaria.
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U2 - 10.1182/blood-2003-11-4090
DO - 10.1182/blood-2003-11-4090
M3 - Article
C2 - 15198952
AN - SCOPUS:4644337767
SN - 0006-4971
VL - 104
SP - 2003
EP - 2006
JO - Blood
JF - Blood
IS - 7
ER -