What you carry at this position in your DNA and what research says about it.
Alzheimer's Disease Risk: 10/10 evidence, 28 publications.
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Sample genotype (not yours): A/A
Higher Alzheimer's and LDL Cholesterol Risk
Two copies of the A allele are associated with an elevated risk of late-onset Alzheimer's disease and higher LDL cholesterol levels. This genetic profile is very common and is often inherited alongside the APOE e4 risk variant.
What this genotype means: Elevated risk of late-onset Alzheimer's disease; Higher levels of LDL cholesterol; Faster rate of age-related cognitive decline.
Sample genotype (not yours): G/A
Lower Alzheimer's and LDL Cholesterol Risk
One copy of the G allele is associated with a reduced risk of late-onset Alzheimer's disease and healthier cholesterol levels. This intermediate profile provides a protective buffer compared to the common A/A genotype.
What this genotype means: Reduced risk of late-onset Alzheimer's disease; Lower levels of LDL cholesterol; Slower rate of age-related cognitive decline.
Sample genotype (not yours): G/G
Lowest Alzheimer's and LDL Cholesterol Risk
Two copies of the protective G allele are associated with the lowest risk of late-onset Alzheimer's disease and the most favorable lipid profile. This profile is linked to lower LDL cholesterol and higher HDL cholesterol.
What this genotype means: Lowest risk of late-onset Alzheimer's disease; Lower LDL and higher HDL cholesterol levels; Better late-life memory performance.
Gene function and biological role
Gene Function: TOMM40 encodes the translocase of outer mitochondrial membrane 40, a protein essential for importing proteins into mitochondria. Mitochondria are the powerhouses of cells, and their proper function is critical for high-energy tissues like the brain. TOMM40 is located on chromosome 19, in very close proximity to the APOE gene, which is the most well-known genetic risk factor for late-onset Alzheimer's disease. Because of this close physical link, variations in TOMM40 are often inherited alongside APOE variants, forming genetic blocks that influence brain health. Studies show that TOMM40 variants independently affect mitochondrial function, amyloid-beta accumulation, and cognitive aging.
Variant Impact: The rs157580 variant is an intronic change within the TOMM40 gene, meaning it does not directly alter the amino acid sequence of the protein but can influence gene expression and splicing. This variant is highly linked to the APOE gene region, which regulates lipid transport and amyloid-beta clearance in the brain. The major A allele is associated with higher levels of LDL cholesterol and an increased risk of late-onset Alzheimer's disease. Conversely, the minor G allele is associated with lower LDL cholesterol, higher HDL cholesterol, and a protective effect against cognitive decline.
Key Insight: This variant is located in a genetic super-locus on chromosome 19 that controls both brain aging and cholesterol metabolism. The protective G allele not only lowers Alzheimer's risk but is also linked to healthier cholesterol profiles.
Location: TOMM40. Chromosome 19 · 19q13.32 · 44.9 Mb
Estimated prevalence by population
Global 11.1%; European 14.8%; African 2.2%; East Asian 29.5%; South Asian 21.4%; Americas 10.6%; Ashkenazi 14.2%; Finnish 7.2%; Middle Eastern 22.0%; Amish 9.9%.
Estimated GG genotype frequency.
Global 40.4%; European 47.4%; African 25.0%; East Asian 49.6%; South Asian 49.7%; Americas 43.9%; Ashkenazi 46.9%; Finnish 39.3%; Middle Eastern 49.8%; Amish 43.1%.
Estimated GA genotype frequency.
Global 48.5%; European 37.8%; African 72.8%; East Asian 20.9%; South Asian 28.9%; Americas 45.5%; Ashkenazi 38.9%; Finnish 53.6%; Middle Eastern 28.2%; Amish 47.1%.
Estimated AA genotype frequency.
Showing effects for A/A genotype
Neurology & Mental Health
Neurodegenerative Diseases
Alzheimer's Disease. Evidence: 10/10. Source: PMID 19125160. Elevated Risk.
Cognitive Performance
Cognitive Decline. Evidence: 3/10. Source: PMID 38306043. Typical.
Memory, Learning & Attention
Memory Performance. Evidence: 3/10. Source: PMID 37984853. Typical.
Cardiovascular & Metabolic
Lipids & Cholesterol
LDL Cholesterol. Evidence: 6/10. Source: PMID 19060910. Higher Levels.
HDL Cholesterol. Evidence: 6/10. Source: PMID 19060911. Lower Levels.
Showing effects for G/A genotype
Alzheimer's Disease. Evidence: 10/10. Source: PMID 19125160. Lower Risk.
Cognitive Decline. Evidence: 3/10. Source: PMID 38306043. Slower Decline.
LDL Cholesterol. Evidence: 6/10. Source: PMID 19060910. Lower Levels.
HDL Cholesterol. Evidence: 6/10. Source: PMID 19060911. Typical.
Showing effects for G/G genotype
Alzheimer's Disease. Evidence: 10/10. Source: PMID 19125160. Lowest Risk.
Memory Performance. Evidence: 3/10. Source: PMID 37984853. Better Performance.
HDL Cholesterol. Evidence: 6/10. Source: PMID 19060911. Higher Levels.
What this genotype means for the people who carry it
Sample genotype: AA (Homozygous)
Two copies of the major risk allele characterize this genotype. Large-scale genome-wide association studies have consistently linked this genotype to an increased risk of late-onset Alzheimer's disease. It is also associated with higher levels of low-density lipoprotein (LDL) cholesterol, often referred to as bad cholesterol, which can impact cardiovascular health. Research indicates that this genetic region influences the accumulation of amyloid-beta plaques in the brain, a hallmark of Alzheimer's pathology. Additionally, individuals with this genotype may experience a faster rate of cognitive decline during normal aging. While this genotype elevates risk, it is not a direct diagnosis, and lifestyle factors play a major role in brain and heart health.
Elevated risk of late-onset Alzheimer's disease; Higher levels of LDL cholesterol; Faster rate of age-related cognitive decline.
Sample genotype: GA (Heterozygous)
One copy of the protective G allele and one copy of the risk-associated A allele make up this profile. This combination is linked to a significantly lower risk of late-onset Alzheimer's disease compared to the A/A genotype. The protective G allele is associated with lower levels of LDL cholesterol and a reduced rate of cognitive decline during aging. Studies on brain biomarkers show that G allele carriers tend to have more favorable amyloid-beta profiles in cerebrospinal fluid. This genetic profile suggests a relative preservation of mitochondrial function and lipid metabolism in the brain. Maintaining a brain-healthy lifestyle can further enhance the protective benefits of this genotype.
Reduced risk of late-onset Alzheimer's disease; Lower levels of LDL cholesterol; Slower rate of age-related cognitive decline.
Sample genotype: GG (Homozygous)
Two copies of the protective minor G allele define this genetic profile. This setup is strongly associated with a reduced risk of late-onset Alzheimer's disease and better preservation of memory performance in late life. On a metabolic level, this genotype is linked to lower levels of LDL cholesterol and higher levels of HDL cholesterol. Research suggests that the G allele helps maintain optimal mitochondrial function in brain cells and supports the clearance of amyloid-beta proteins. Individuals with this genotype also tend to show slower rates of cognitive decline as they age. This combination of cardiovascular and neurological benefits makes the G/G genotype highly favorable for healthy aging.
Lowest risk of late-onset Alzheimer's disease; Lower LDL and higher HDL cholesterol levels; Better late-life memory performance.
Variants with shared genetic architecture
rs2075650 · TOMM40 Gene · Chr 19 · Alzheimer's Disease Risk
rs157582 · TOMM40 Gene · Chr 19 · Cognitive Decline Risk
rs1160985 · TOMM40 Gene · Chr 19 · Alzheimer's Disease Risk
Content updated August 2026.
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