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Revisiting the malaria hypothesis: accounting for polygenicity and pleiotropy
Emily R Ebel1, Lawrence H Uricchio2, Dmitri A Petrov3
1Department of Pediatrics, Stanford University School of Medicine, Stanford, CA 94305, USA; Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA 94305, USA.
Trends in Parasitology
|January 23, 2022
Summary
The malaria hypothesis may not fully explain genetic variations related to malaria risk. Other evolutionary forces likely shape the global distribution of these genetic traits.
Area of Science:
- Population Genetics
- Human Evolution
- Genomics
Background:
- The malaria hypothesis posits that genetic variants conferring malaria resistance are maintained by balancing selection.
- Three known red blood cell gene variants show higher frequency in African populations, supporting this hypothesis.
- However, severe malaria heritability is largely attributed to numerous small-effect genome-wide loci.
Purpose of the Study:
- To investigate whether genetic variations associated with malaria risk are solely driven by malaria prevalence.
- To explore the role of other evolutionary forces in shaping the global distribution of malaria-related genetic variation.
Main Methods:
- Analysis of genome-wide association studies (GWAS) data.
- Comparison of allele frequencies across different global populations.
- Examination of pleiotropic effects of genetic variants.
Main Results:
- Protective variants in red cell genes are more common in African populations.
- Many genome-wide loci with small effects contribute significantly to severe malaria heritability.
- Alleles and red cell traits linked to minor malaria risk reduction are not enriched in African populations.
Conclusions:
- The malaria hypothesis alone may not account for the global distribution of all genetic variations influencing malaria risk.
- Pleiotropy and other selective or neutral evolutionary forces likely play a significant role.
- Further research is needed to understand the complex genetic architecture of malaria risk.
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