What you carry at this position in your DNA and what research says about it.
Alzheimer's Disease Risk: 5/10 evidence, 16 publications.
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Sample genotype (not yours): C/C
Typical Alzheimer's Risk and Normal Enzyme Activity
Normal levels of butyrylcholinesterase enzyme activity help maintain standard cognitive health. This genotype is associated with a typical response to standard dementia medications.
What this genotype means: Normal butyrylcholinesterase enzyme activity; Typical baseline risk of late-onset Alzheimer's disease; Standard response to rivastigmine therapy.
Sample genotype (not yours): C/T
Slightly Increased Alzheimer's Risk and Reduced Enzyme Activity
A single copy of the T allele reduces butyrylcholinesterase enzyme activity, which may slightly elevate the risk of late-onset Alzheimer's disease.
What this genotype means: Reduced butyrylcholinesterase enzyme activity; Slightly increased risk of late-onset Alzheimer's disease; Altered response to dementia medications.
Sample genotype (not yours): T/T
Increased Alzheimer's Risk and Significantly Reduced Enzyme Activity
Two copies of the T allele significantly lower butyrylcholinesterase enzyme activity, which is linked to a higher risk of late-onset Alzheimer's disease.
What this genotype means: Significantly reduced butyrylcholinesterase enzyme activity; Increased risk of late-onset Alzheimer's disease; Poorer response to rivastigmine and memantine.
Gene function and biological role
Gene Function: The BCHE gene encodes butyrylcholinesterase, a major cholinesterase enzyme found in the blood and brain [1]. This enzyme plays a crucial role in breaking down acetylcholine, a key neurotransmitter involved in memory, attention, and cognitive function [1]. It also serves as an important bioscavenger, detoxifying various chemical compounds, including certain anesthetics, muscle relaxants, and pesticides [2]. Variations in this gene can alter enzyme activity levels, which has significant implications for neurodegenerative disease risk and drug metabolism [3].
Variant Impact: The rs1803274 variant, commonly known as the K variant, is a missense mutation in the BCHE gene. This genetic change replaces the amino acid alanine with threonine at position 567 of the protein, which destabilizes the enzyme's structure [4]. This structural alteration leads to a roughly 30% reduction in butyrylcholinesterase enzyme activity in the blood [1]. The reduced activity is widely studied for its potential role in accelerating cognitive decline and modifying the risk of late-onset Alzheimer's disease [3]. Additionally, this variant is a key pharmacogenomic marker that influences how patients respond to various cholinesterase inhibitor therapies [5].
Key Insight: The K variant reduces the body's ability to clear certain muscle relaxants used in surgery, and it can completely alter which Alzheimer's medication works best for a patient.
Location: BCHE. Chromosome 3 · 3q26.1 · 165.8 Mb
Estimated prevalence by population
Global 66.8%; European 64.4%; African 65.8%; East Asian 77.9%; South Asian 69.3%; Americas 74.3%; Ashkenazi 67.8%; Finnish 69.7%; Middle Eastern 63.9%; Amish 62.1%.
Estimated CC genotype frequency.
Global 29.8%; European 31.7%; African 30.6%; East Asian 20.7%; South Asian 27.9%; Americas 23.8%; Ashkenazi 29.0%; Finnish 27.6%; Middle Eastern 32.1%; Amish 33.4%.
Estimated CT genotype frequency.
Global 3.4%; European 3.9%; African 3.6%; East Asian 1.4%; South Asian 2.8%; Americas 1.9%; Ashkenazi 3.1%; Finnish 2.7%; Middle Eastern 4.0%; Amish 4.5%.
Estimated TT genotype frequency.
Showing effects for C/C genotype
Neurology & Mental Health
Neurodegenerative Diseases
Alzheimer's Disease. Evidence: 5/10. Source: PMID 30914707. Typical Risk.
Rivastigmine Response. Evidence: 5/10. Source: PMID 25376930. Stronger Response.
Donepezil Response. Evidence: 5/10. Source: PMID 27567841. Typical Response.
Memantine Response. Evidence: 5/10. Source: PMID 25376930. Typical Response.
Pharmacogenomics
Anesthesia Response
BChE Enzyme Activity. Evidence: 8/10. Source: PMID 21862451. Normal Activity.
Cardiovascular & Metabolic
Lipids & Cholesterol
Apolipoprotein M Levels. Evidence: 5/10. Source: PMID 29875488. Typical Levels.
Showing effects for C/T genotype
Alzheimer's Disease. Evidence: 5/10. Source: PMID 30914707. Slightly Increased.
Rivastigmine Response. Evidence: 5/10. Source: PMID 25376930. Variable Response.
Donepezil Response. Evidence: 5/10. Source: PMID 27567841. Stronger Response.
Memantine Response. Evidence: 5/10. Source: PMID 25376930. Poorer Response.
BChE Enzyme Activity. Evidence: 8/10. Source: PMID 21862451. Reduced Activity.
Apolipoprotein M Levels. Evidence: 5/10. Source: PMID 29875488. Higher Levels.
Showing effects for T/T genotype
Alzheimer's Disease. Evidence: 5/10. Source: PMID 30914707. Increased Risk.
Rivastigmine Response. Evidence: 5/10. Source: PMID 25376930. Poorer Response.
BChE Enzyme Activity. Evidence: 8/10. Source: PMID 21862451. Low Activity.
What this genotype means for the people who carry it
Sample genotype: CC (Homozygous)
Two copies of the C allele result in normal butyrylcholinesterase enzyme activity, which is the baseline state for the majority of the population [1]. This normal enzyme function is associated with a typical, baseline risk for late-onset Alzheimer's disease [2]. In clinical settings, individuals with this genotype generally show a standard, favorable response to the cholinesterase inhibitor rivastigmine [3]. However, they may not experience the enhanced response to donepezil seen in carriers of the variant allele [4]. Maintaining normal enzyme levels is also important for the body's ability to break down certain muscle relaxants and environmental toxins [1].
Normal butyrylcholinesterase enzyme activity; Typical baseline risk of late-onset Alzheimer's disease; Standard response to rivastigmine therapy.
Sample genotype: CT (Heterozygous)
A single copy of the T allele, also known as the K variant, leads to a reduction in butyrylcholinesterase enzyme activity [1]. This decrease in enzyme function has been linked in several studies to a moderately increased risk of developing late-onset Alzheimer's disease, particularly when co-inherited with other risk factors like APOE4 [2]. The reduction in enzyme activity can also influence the effectiveness of common dementia treatments [3]. Specifically, carriers of this variant may show a poorer response to rivastigmine or memantine [3]. Conversely, some clinical evidence suggests they might experience a better response to donepezil [4].
Reduced butyrylcholinesterase enzyme activity; Slightly increased risk of late-onset Alzheimer's disease; Altered response to dementia medications.
Sample genotype: TT (Homozygous)
Two copies of the T allele result in the homozygous K variant, which significantly reduces butyrylcholinesterase enzyme activity by approximately 30% [1]. This pronounced reduction in enzyme function is associated with an increased risk of late-onset Alzheimer's disease and accelerated cognitive decline [2]. The altered enzyme structure also has a major impact on how the body processes dementia medications [3]. Clinical studies indicate that individuals with this genotype often have a poorer response to rivastigmine and memantine [3]. However, they may show a significantly better response to donepezil compared to non-carriers [2].
Significantly reduced butyrylcholinesterase enzyme activity; Increased risk of late-onset Alzheimer's disease; Poorer response to rivastigmine and memantine.
Variants with shared genetic architecture
rs1799807 · BCHE Gene · Chr 3 · Anesthetic Sensitivity
rs2471738 · MAPT Gene · Chr 17 · Alzheimer's and Cognition
rs6280 · DRD3 Gene · Chr 3 · Dopamine Receptor Sensitivity
Content updated August 2026.
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