- Being heterozygous (one having one gene for the sickle-cell anemia) has more resistance to malaria which is why it is evolutionarily found to be more prevalent in areas where malaria is a prevalent disease. 
- When infected with malaria, the cells sickle due to a lower pH in the blood causing an increasing likelihood of the S hemoglobin cells to sickle. 
- In early stages of infection, the parasitized cells sickle and disrupt the parasite and the spleen can remove the infected erythrocytes. 
- In later stages in infection, the parasitized erythrocytes disrupt the parasite mechanically because of their sickle shape. 
- This makes the population more heterozygous for the S hemoglobin gene for sickle-cell anemia. 


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- Inheritable blood disease 
- Homozygous (or those with both genes) people with hemoglobin S have sickle-cell disease. 
- Heterozygous individuals usually live healthy lives but have lower erythrocyte count.
- The cells form a sickle shape because of one amino acid is mutated (Glu -> Val)
- This amino acid change allows the hemoglobin to bind to other hemoglobin at the binding pocket causing a mass sickle shape of the blood cells. 
- It is difficult for cells to pass through capillaries and deliver oxygen which can cause tissue death. 


Sickle-cell anemia

Voet, D., Voet, J. G., & Pratt, C. W. (2013). Chapter 7: Protein Function: Myoglobin and Hemoglobin, Muscle Contractions, and Antibodies. In Fundamentals of biochemistry: Life at the molecular level (4th ed., pp. 176-216). Hoboken, NJ: Wiley. Retrieved February 21, 2021, from archive.org.

Fundamental of biochemistry: Life of the molecular level 4th edition: Chapter 7

Sickle-Cell Anemia and Malaria

- Administering hydroxyurea has been determined to be an effective treatment for sickle-cell anemia.
- It increases the fraction of cells that have fetal hemoglobin which has a separate subunit gamma rather than the defective beta chain that is found in mutated hemoglobin blood cells. 
- Still little is know of this mechanism however. 

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