Why preeclampsia still exists?

Area of Science:

• Human Genetics
• Reproductive Medicine
• Evolutionary Biology

Background:

• Preeclampsia (PE) affects up to 10% of human pregnancies and has a known genetic component.
• Despite Darwinian pressures, PE-predisposing alleles remain common, suggesting a balancing selection mechanism.
• Reduced PE risk and severity in consecutive pregnancies with the same partner indicate familial and partner-specific influences.

Purpose of the Study:

• To investigate the evolutionary maintenance of preeclampsia-predisposing alleles within human populations.
• To explore the role of familial structure and mating patterns in allele frequency dynamics.
• To propose a hypothesis explaining the persistence of potentially detrimental genetic variants.

Main Methods:

• Analysis of familial structures and epidemiological data related to preeclampsia.
• Modeling of allele frequency dynamics under different mating scenarios.
• Examination of known predisposing gene polymorphisms in preeclampsia.

Main Results:

• Preeclampsia-predisposing alleles can be differentially maintained based on familial structures.
• The peculiar feature of decreasing risk with consecutive pregnancies suggests a unique evolutionary dynamic.
• A trade-off mechanism is proposed to explain allele frequency maintenance.

Conclusions:

• The persistence of preeclampsia-predisposing alleles is likely due to a balance between evolutionary pressures.
• Benefits of exogamy and maintaining genetic diversity may favor the retention of these alleles.
• Increased fitness from stable paternal investment could also contribute to allele maintenance, balancing PE risks.