What you carry at this position in your DNA and what research says about it.
Blood Lipid Levels: 10/10 evidence, 20 publications.
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Sample genotype (not yours): C/C
Favorable Lipid and Fatty Acid Profile
This genotype is associated with lower triglycerides and higher levels of protective HDL cholesterol. It also correlates with higher levels of beneficial omega-3 fatty acids.
What this genotype means: Lower circulating triglycerides; Higher HDL cholesterol; Higher omega-3 and DHA levels.
Sample genotype (not yours): C/T
Slightly Less Favorable Lipid Profile
Carrying one copy of the T allele is linked to slightly higher triglycerides and lower HDL cholesterol. It also correlates with minor reductions in circulating omega-3 fatty acids.
What this genotype means: Slightly elevated triglycerides; Slightly lower HDL cholesterol; Modestly lower omega-3 levels.
Sample genotype (not yours): T/T
Elevated Triglycerides and Lower HDL Cholesterol
Having two copies of the T allele is associated with higher triglyceride levels and lower HDL cholesterol. It also correlates with lower levels of beneficial omega-3 fatty acids.
What this genotype means: Elevated circulating triglycerides; Lower HDL cholesterol; Reduced omega-3 and DHA levels.
Gene function and biological role
Gene Function: The CPT1A gene encodes carnitine palmitoyltransferase 1A, a key enzyme located in the outer mitochondrial membrane of liver cells [1]. This enzyme acts as the rate-limiting step in mitochondrial beta-oxidation by controlling the entry of long-chain fatty acids into the mitochondria [2]. Through this pathway, the body breaks down fats to generate energy, especially during periods of fasting [1]. Proper functioning of this gene is essential for maintaining systemic energy balance and regulating circulating lipid concentrations [2].
Variant Impact: The rs2229738 variant is a missense mutation in the CPT1A gene that results in the substitution of the amino acid alanine with threonine at position 275 of the protein [3]. This structural change alters the enzyme's efficiency in processing fatty acids, directly impacting lipid metabolism [4]. While severe mutations in this gene can cause clinical metabolic disorders, this specific variant is classified as benign for classic deficiency syndromes [3]. Instead, it acts as a common genetic modifier of blood lipid profiles, particularly affecting circulating triglycerides and high-density lipoprotein levels [4].
Key Insight: This variant acts as a metabolic dial, shifting the balance between how your body stores triglycerides and how it transports protective HDL cholesterol.
Location: CPT1A. Chromosome 11 · 11q13.3 · 68.8 Mb
Estimated prevalence by population
Global 89.5%; European 85.6%; African 97.6%; East Asian 99.8%; South Asian 94.7%; Americas 94.5%; Ashkenazi 83.9%; Finnish 69.5%; Middle Eastern 90.1%; Amish 90.1%.
Estimated CC genotype frequency.
Global 10.0%; European 13.8%; African 2.4%; East Asian 0.2%; South Asian 5.2%; Americas 5.4%; Ashkenazi 15.4%; Finnish 27.7%; Middle Eastern 9.7%; Amish 9.6%.
Estimated CT genotype frequency.
Global 0.5%; European 0.6%; African < 0.1%; East Asian < 0.1%; South Asian 0.1%; Americas 0.1%; Ashkenazi 0.7%; Finnish 2.8%; Middle Eastern 0.3%; Amish 0.3%.
Estimated TT genotype frequency.
Showing effects for C/C genotype
Cardiovascular & Metabolic
Lipids & Cholesterol
Triglycerides. Evidence: 10/10. Source: PMID 35213538. Lower Levels.
HDL Cholesterol. Evidence: 10/10. Source: PMID 35213538. Higher Levels.
Nutrition & Metabolism
Macronutrient Metabolism
Omega-3 Fatty Acids. Evidence: 10/10. Source: PMID 35213538. Higher Levels.
Docosahexaenoic Acid. Evidence: 10/10. Source: PMID 35213538. Higher Levels.
Showing effects for C/T genotype
Triglycerides. Evidence: 10/10. Source: PMID 35213538. Slightly Higher.
HDL Cholesterol. Evidence: 10/10. Source: PMID 35213538. Slightly Lower.
Omega-3 Fatty Acids. Evidence: 10/10. Source: PMID 35213538. Slightly Lower.
Docosahexaenoic Acid. Evidence: 10/10. Source: PMID 35213538. Slightly Lower.
Showing effects for T/T genotype
Triglycerides. Evidence: 10/10. Source: PMID 35213538. Higher Levels.
HDL Cholesterol. Evidence: 10/10. Source: PMID 35213538. Lower Levels.
Omega-3 Fatty Acids. Evidence: 10/10. Source: PMID 35213538. Lower Levels.
Docosahexaenoic Acid. Evidence: 10/10. Source: PMID 35213538. Lower Levels.
What this genotype means for the people who carry it
Sample genotype: CC (Homozygous)
Having two copies of the C allele supports optimal mitochondrial fat processing by the CPT1A enzyme [1]. Large-scale metabolic studies show that this genotype is linked to lower circulating triglyceride levels and higher levels of high-density lipoprotein (HDL) cholesterol, often referred to as good cholesterol [2]. Additionally, individuals with this genotype tend to maintain higher circulating levels of beneficial polyunsaturated fatty acids, including docosahexaenoic acid (DHA) and overall omega-3 fatty acids [3]. This combination of low triglycerides, high HDL, and robust omega-3 levels is generally considered highly favorable for cardiovascular and metabolic health [2].
Lower circulating triglycerides; Higher HDL cholesterol; Higher omega-3 and DHA levels.
Sample genotype: CT (Heterozygous)
Carrying one copy of the T allele slightly shifts the efficiency of the CPT1A enzyme in processing fatty acids [1]. Metabolic research indicates that this intermediate state is associated with a modest increase in circulating triglycerides and a corresponding slight decrease in protective HDL cholesterol [2]. Furthermore, studies have noted a mild reduction in circulating polyunsaturated fatty acids, such as docosahexaenoic acid (DHA) and total omega-3 fatty acids, compared to the common genotype [3]. While these changes are typically subtle, they represent a slightly less optimal lipid balance that can be managed effectively through standard dietary and lifestyle choices [2].
Slightly elevated triglycerides; Slightly lower HDL cholesterol; Modestly lower omega-3 levels.
Sample genotype: TT (Homozygous)
Having two copies of the T allele alters the rate-limiting step of mitochondrial fatty acid oxidation governed by CPT1A [1]. Genome-wide association studies consistently link this genotype to significantly higher circulating triglycerides and lower levels of cardioprotective HDL cholesterol [2]. Additionally, individuals with this genotype exhibit lower levels of essential polyunsaturated fatty acids, including docosahexaenoic acid (DHA) and total omega-3 fatty acids [3]. Although ClinVar confirms this variant is benign and does not cause clinical carnitine palmitoyltransferase deficiency, the resulting lipid profile is less favorable for long-term cardiovascular health [2].
Elevated circulating triglycerides; Lower HDL cholesterol; Reduced omega-3 and DHA levels.
Variants with shared genetic architecture
rs17326656 · LHCGR Gene · Chr 2 · Abdominal Fat and Lipids
rs4846914 · GALNT2 Gene · Chr 1 · Triglyceride Levels
rs55747707 · MLXIPL Gene · Chr 7 · Cholesterol and Lipids
Carnitine Palmitoyltransferase 1A Deficiency.
Genome-wide characterization of circulating metabolic biomarkers.
Content updated August 2026.
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