What you carry at this position in your DNA and what research says about it.
Alzheimer's Disease Risk: 8/10 evidence, 8 publications.
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Sample genotype (not yours): A/A
Higher Alzheimer's Disease Risk
Late-onset Alzheimer's disease risk is significantly higher for those with this genetic profile. However, these same genetic factors are associated with typical or lower total and LDL cholesterol levels.
What this genotype means: Significantly higher risk of late-onset Alzheimer's disease; Typical or lower total and LDL cholesterol levels.
Sample genotype (not yours): A/G
Typical Alzheimer's and Cholesterol Risk
Balanced genetic influences result in a typical risk profile for both cognitive decline and lipid levels. This heterozygous state represents an intermediate position between the two extremes of this genetic trade-off.
What this genotype means: Typical risk for late-onset Alzheimer's disease; Typical total and LDL cholesterol levels.
Sample genotype (not yours): G/G
Lower Alzheimer's Risk but Higher Cholesterol
Neurological protection comes with a cardiovascular trade-off for this genetic profile. While the risk of late-onset Alzheimer's disease is significantly lower, total and LDL cholesterol levels tend to be higher.
What this genotype means: Significantly lower risk of late-onset Alzheimer's disease; Higher total and LDL cholesterol levels.
Gene function and biological role
Gene Function: The TOMM40 gene encodes the translocase of the outer mitochondrial membrane 40, a channel-forming protein essential for importing proteins into mitochondria. Proper mitochondrial protein import is vital for maintaining cellular energy production, particularly in high-demand tissues like the brain. Because of its physical proximity to the APOE gene on chromosome 19, TOMM40 is highly linked to cardiovascular and neurodegenerative traits. Variations in this gene can influence mitochondrial efficiency, potentially affecting susceptibility to age-related cognitive decline.
Variant Impact: The rs8106922 variant is an intronic single nucleotide polymorphism located within the TOMM40 gene. This genetic change is situated in a region that is inherited alongside the APOE gene, which is heavily involved in lipid transport and neurobiology. The variant is associated with differences in both mitochondrial outer membrane translocase expression and lipid metabolism. Specifically, the A allele is linked to an increased risk of late-onset Alzheimer's disease. Conversely, the G allele is associated with higher levels of circulating total and LDL cholesterol.
Key Insight: This variant represents a direct genetic trade-off, where the allele that protects against Alzheimer's disease also increases total and LDL cholesterol levels.
Location: TOMM40. Chromosome 19 · 19q13.32 · 44.9 Mb
Estimated prevalence by population
Global 41.8%; European 34.9%; African 57.0%; East Asian 61.2%; South Asian 41.8%; Americas 38.7%; Ashkenazi 34.8%; Finnish 25.2%; Middle Eastern 40.1%; Amish 20.8%.
Estimated AA genotype frequency.
Global 44.6%; European 48.3%; African 37.0%; East Asian 34.1%; South Asian 45.7%; Americas 47.0%; Ashkenazi 48.4%; Finnish 50.0%; Middle Eastern 46.4%; Amish 49.6%.
Estimated AG genotype frequency.
Global 13.6%; European 16.7%; African 6.0%; East Asian 4.7%; South Asian 12.5%; Americas 14.3%; Ashkenazi 16.8%; Finnish 24.8%; Middle Eastern 13.4%; Amish 29.6%.
Estimated GG genotype frequency.
Showing effects for A/A genotype
Neurology & Mental Health
Neurodegenerative Diseases
Alzheimer's Disease. Evidence: 8/10. Source: PMID 39998322. Increased Risk.
Memory, Learning & Attention
Memory Performance. Evidence: 6/10. Source: PMID 37984853. Reduced Performance.
Cardiovascular & Metabolic
Lipids & Cholesterol
Total Cholesterol. Evidence: 6/10. Source: PMID 29507422. Typical Levels.
LDL Cholesterol. Evidence: 6/10. Source: PMID 29507422. Typical Levels.
Showing effects for A/G genotype
Alzheimer's Disease. Evidence: 8/10. Source: PMID 39998322. Typical Risk.
Memory Performance. Evidence: 6/10. Source: PMID 37984853. Typical Performance.
Showing effects for G/G genotype
Alzheimer's Disease. Evidence: 8/10. Source: PMID 39998322. Lower Risk.
Total Cholesterol. Evidence: 6/10. Source: PMID 29507422. Increased Levels.
LDL Cholesterol. Evidence: 6/10. Source: PMID 29507422. Increased Levels.
What this genotype means for the people who carry it
Sample genotype: AA (Homozygous)
Mitochondrial function plays a critical role in brain health and the aging process. The TOMM40 gene encodes an outer mitochondrial membrane protein channel essential for protein import. The rs8106922 variant, located within an intron of TOMM40, is in strong linkage disequilibrium with the APOE gene region. Research indicates that the A allele is strongly associated with an increased risk of late-onset Alzheimer's disease. Having two copies of the A allele is linked to a higher likelihood of cognitive decline and poorer memory performance in older age. On the positive side, this genotype is associated with lower levels of total and LDL cholesterol. This represents a complex genetic trade-off between cardiovascular biomarkers and neurodegenerative risk.
Significantly higher risk of late-onset Alzheimer's disease; Typical or lower total and LDL cholesterol levels.
Sample genotype: AG (Heterozygous)
Inheriting one A allele and one G allele provides a balanced genetic profile. The A allele is associated with an elevated risk of late-onset Alzheimer's disease, while the G allele is linked to higher total and LDL cholesterol levels. Because this genotype carries one of each allele, the opposing risks tend to moderate each other. Studies on memory performance in older adults show that heterozygous individuals typically perform at average levels. Similarly, lipid profiles generally remain within the typical range for the population. This genetic combination highlights how different variants in the TOMM40-APOE region influence both neurological and cardiovascular health markers.
Typical risk for late-onset Alzheimer's disease; Typical total and LDL cholesterol levels.
Sample genotype: GG (Homozygous)
Mitochondrial efficiency and lipid metabolism are closely linked through the TOMM40-APOE gene cluster. Having two copies of the G allele is associated with a significantly reduced risk of late-onset Alzheimer's disease. This protective effect is one of the more robust genetic findings related to cognitive preservation in older age. However, this benefit is accompanied by a metabolic trade-off. The G allele is strongly linked to higher levels of total and LDL cholesterol. This elevation in circulating lipids can contribute to cardiovascular risk if not managed through lifestyle or medical interventions. Understanding this dual effect allows for a more personalized approach to long-term health planning.
Significantly lower risk of late-onset Alzheimer's disease; Higher total and LDL cholesterol levels.
Variants with shared genetic architecture
rs157580 · TOMM40 Gene · Chr 19 · Alzheimer's Disease Risk
rs2075650 · TOMM40 Gene · Chr 19 · Alzheimer's Disease Risk
rs157582 · TOMM40 Gene · Chr 19 · Cognitive Decline Risk
Content updated August 2026.
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