Sickle haemoglobin, haemoglobin C and malaria mortality feedbacks.

Area of Science:

• Population genetics
• Evolutionary biology
• Molecular genetics

Background:

• Sickle haemoglobin (HbS) and haemoglobin C (HbC) are genetic variants offering malaria protection.
• HbS is more widespread than HbC, despite HbS homozygosity causing more severe disease (sickle cell anemia) than HbC homozygosity.
• The differing geographical distributions may relate to varying malaria protection levels in heterozygotes or parasite transmission dynamics.

Purpose of the Study:

• To investigate the evolutionary dynamics of HbS and HbC.
• To understand the role of malaria selection in the differential success of these alleles.

Main Methods:

• Utilized a population genetic model.
• Simulated evolutionary consequences based on malaria selection strength correlated with allele frequencies.

Main Results:

• Positive correlation between malaria selection pressure and HbS or HbC frequency facilitates HbS allele success.
• HbS demonstrated an advantage in competitive interactions between the two alleles under these conditions.

Conclusions:

• A feedback mechanism, where variant haemoglobins intensify malaria selection, likely contributed to HbS's global prevalence over HbC.
• This mechanism helps explain HbS's success despite its higher associated blood disorder cost.