What you carry at this position in your DNA and what research says about it.
Blood Lipid Levels: 8/10 evidence, 9 publications.
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Sample genotype (not yours): G/G
Favorable Lipid Profile and Lower Triglycerides
Lower circulating levels of triglycerides and total cholesterol characterize this genetic profile. It supports overall cardiovascular health by maintaining efficient lipid clearance.
What this genotype means: Lower circulating triglycerides; Lower VLDL cholesterol; Typical cardiac conduction.
Sample genotype (not yours): G/T
Moderately Elevated Triglycerides and Cholesterol
Slightly higher levels of triglycerides and total cholesterol are associated with this heterozygous state. This intermediate profile suggests a modest increase in circulating blood lipids.
What this genotype means: Slightly higher triglycerides; Moderately elevated VLDL; Slightly longer PR interval.
Sample genotype (not yours): T/T
Elevated Triglycerides and Total Cholesterol
Elevated levels of circulating triglycerides and VLDL cholesterol are associated with this genotype. This profile may increase the risk of cardiovascular strain over time.
What this genotype means: Elevated circulating triglycerides; Higher total and VLDL cholesterol; Slightly longer cardiac PR interval.
Gene function and biological role
Gene Function: The AFF1 gene encodes a transcription factor that plays a critical role in regulating gene expression during development and cellular differentiation [1]. It is a member of the AF4/FMR2 family and is widely known for its involvement in chromosomal translocations associated with acute lymphoblastic leukemia [1]. Beyond its role in oncology, AFF1 has emerged as an important player in metabolic regulation, particularly in the clearance and transport of circulating lipids [2]. Studies have linked variation in this gene to systemic differences in lipid fractions, including triglycerides and very-low-density lipoproteins [2]. It is also expressed in cardiac tissue, where it may influence electrical conduction pathways [3].
Variant Impact: The rs442177 variant is an intronic change located within the AFF1 gene on chromosome 4. As an intron variant, it does not alter the amino acid sequence of the protein directly but is thought to influence gene expression levels or splicing efficiency [4]. This genetic marker is strongly associated with circulating levels of triglycerides and various cholesterol fractions [4] [2]. The T allele is the major allele globally and is consistently linked to higher levels of triglycerides and VLDL cholesterol [2]. Conversely, the G allele is associated with a more favorable lipid profile, characterized by lower circulating triglycerides [2].
Key Insight: Although AFF1 is most famous for its role in childhood leukemia, common variants within its introns actually help dictate daily blood lipid levels and heart conduction times.
Location: AFF1. Chromosome 4 · 4q22.1 · 87.1 Mb
Estimated prevalence by population
Global 19.4%; European 16.9%; African 26.1%; East Asian 18.3%; South Asian 25.8%; Americas 12.5%; Ashkenazi 6.9%; Finnish 22.5%; Middle Eastern 10.4%; Amish 9.2%.
Estimated GG genotype frequency.
Global 48.4%; European 48.4%; African 50.0%; East Asian 49.0%; South Asian 50.0%; Americas 45.7%; Ashkenazi 38.7%; Finnish 49.9%; Middle Eastern 43.7%; Amish 42.3%.
Estimated GT genotype frequency.
Global 32.2%; European 34.7%; African 23.9%; East Asian 32.7%; South Asian 24.2%; Americas 41.9%; Ashkenazi 54.5%; Finnish 27.7%; Middle Eastern 45.8%; Amish 48.5%.
Estimated TT genotype frequency.
Showing effects for G/G genotype
Cardiovascular & Metabolic
Lipids & Cholesterol
Triglycerides. Evidence: 8/10. Source: PMID 20686565. Lower Levels.
Total Cholesterol. Evidence: 8/10. Source: PMID 38448586. Lower Levels.
VLDL Cholesterol. Evidence: 6/10. Source: PMID 38448586. Lower Levels.
Heart Rhythm & Conduction
PR Interval. Evidence: 6/10. Source: PMID 32439900. Typical Conduction.
Blood Cell & Iron Traits
Hemoglobin Levels. Evidence: 6/10. Source: PMID 27863252. Slightly Higher.
Showing effects for G/T genotype
Triglycerides. Evidence: 8/10.
Total Cholesterol. Evidence: 8/10. Source: PMID 38448586. Slightly Higher.
VLDL Cholesterol. Evidence: 6/10. Source: PMID 38448586. Slightly Higher.
PR Interval. Evidence: 6/10. Source: PMID 32439900. ~0.43 ms Longer.
Hemoglobin Levels. Evidence: 6/10. Source: PMID 27863252. Typical.
Showing effects for T/T genotype
Total Cholesterol. Evidence: 8/10. Source: PMID 38448586. Higher Levels.
VLDL Cholesterol. Evidence: 6/10. Source: PMID 38448586. Higher Levels.
PR Interval. Evidence: 6/10. Source: PMID 32439900. ~0.86 ms Longer.
Hemoglobin Levels. Evidence: 6/10. Source: PMID 27863252. Slightly Lower.
What this genotype means for the people who carry it
Sample genotype: GG (Homozygous)
A highly favorable metabolic profile is associated with the G/G genotype. Large-scale genomic studies have consistently linked this genetic combination to lower circulating levels of triglycerides and very-low-density lipoprotein (VLDL) cholesterol [1] [2]. These lower lipid levels are generally protective against the development of plaque in the arteries and associated cardiovascular issues [3]. Additionally, this profile is linked to a slightly shorter, typical cardiac PR interval, representing normal electrical conduction times in the heart [4]. Slightly higher hemoglobin levels are also observed, supporting efficient oxygen transport [5]. Overall, this genetic combination represents a baseline of efficient lipid metabolism and typical cardiac conduction.
Lower circulating triglycerides; Lower VLDL cholesterol; Typical cardiac conduction.
Sample genotype: GT (Heterozygous)
A moderate increase in circulating triglycerides and very-low-density lipoprotein (VLDL) cholesterol is common with this heterozygous profile [1] [2]. This intermediate metabolic state means that lipid clearance may be slightly less efficient compared to the G/G genotype [2]. Over time, elevated circulating lipids can contribute to a higher risk of arterial plaque accumulation and cardiovascular strain [3]. A minor increase in the cardiac PR interval is also associated with this variant, which measures the time it takes for electrical signals to travel through the heart's upper chambers [4].
Slightly higher triglycerides; Moderately elevated VLDL; Slightly longer PR interval.
Sample genotype: TT (Homozygous)
Strong associations with elevated levels of circulating triglycerides and total cholesterol characterize the T/T genotype [1] [2]. Higher levels of very-low-density lipoprotein (VLDL) and chylomicrons are also common with this combination [2]. These elevated lipid fractions are well-established risk factors for arterial plaque buildup and coronary artery disease [3]. Furthermore, a slightly longer cardiac PR interval is associated with this genotype, indicating a minor delay in electrical conduction through the heart [4]. Proactive lifestyle choices, such as a diet low in saturated fats and regular aerobic exercise, are highly effective at mitigating these genetic lipid elevations. Routine lipid screenings can help ensure these markers remain within a healthy range.
Elevated circulating triglycerides; Higher total and VLDL cholesterol; Slightly longer cardiac PR interval.
Variants with shared genetic architecture
rs3775228 · AFF1 Gene · Chr 4 · Triglyceride Levels
rs1042034 · APOB Gene · Chr 2 · Cholesterol and Lipids
rs115849089 · LPL Gene · Chr 8 · Triglyceride Levels
Genetic variants influencing circulating lipid levels and risk of coronary artery disease.
Genome-wide characterization of circulating metabolic biomarkers.
Biological, clinical and population relevance of 95 loci for blood lipids.
The Allelic Landscape of Human Blood Cell Trait Variation and Links to Common Complex Disease.
Content updated August 2026.
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