Mortality differences by APOE genotype estimated from demographic synthesis

Area of Science:

• Genetics
• Demography
• Epidemiology

Background:

• The apolipoprotein E (APOE) 4 allele is linked to higher risks of ischemic heart disease and Alzheimer's disease.
• APOE 4 allele frequency decreases with age, suggesting an association with increased mortality.
• Understanding the age-specific mortality risks associated with APOE genotypes is crucial for public health.

Purpose of the Study:

• To extend demographic models for estimating relative mortality risks based on gene frequencies across age groups.
• To synthesize gene frequency data with cohort study mortality data by genotype.
• To quantify the association between APOE genotype and mortality risk across different ages.

Main Methods:

• Developed and applied an extended demographic model combining gene frequencies and cohort mortality data.
• Analyzed data from Denmark, Finland, France, Italy, Sweden, and the United States.
• Calculated relative mortality risks for different APOE genotypes (e.g., 3/4, 4/4, 2/3) compared to the 3/3 genotype.

Main Results:

• Near age 50, the APOE 3/4 genotype showed a 1.34-fold increased mortality risk (95% CI 1.18-1.67) compared to 3/3.
• The APOE 4/4 genotype exhibited a relative risk of 1.81, while the 2/3 genotype was protective with a relative risk of 0.84 (0.68-0.93).
• These genotype-specific mortality risks converged towards 1.0 at older ages, with minimal variation in mortality over age 100.

Conclusions:

• APOE genotype influences mortality risk, particularly in mid-life, but this association diminishes significantly in centenarians.
• The demographic modeling approach effectively integrates genetic and mortality data to assess population-level health risks.
• Findings suggest that while APOE 4 poses risks, its impact on survival is limited at extreme ages.