EPA Omega-3 Levels and Your Genetics
EPA Omega-3 Genetics: TMEM258, ELOVL2, and FADS1 | ExomeDNA
By the ExomeDNA Research Team | Last reviewed May 2026
Research base: Moderate.
What is EPA omega-3?
Eicosapentaenoic acid (EPA) is a 20-carbon omega-3 polyunsaturated fatty acid with five double bonds (20:5n-3). It is found in fatty fish, algal oils, and fish oil supplements, and is also synthesized endogenously from dietary alpha-linolenic acid (ALA, 18:3n-3) through a series of desaturation and elongation steps. In the body, EPA serves as the direct precursor for a class of anti-inflammatory signaling molecules—3-series prostaglandins and 5-series leukotrienes—and acts as a precursor to DHA through further elongation.
Plasma EPA levels reflect a combination of dietary intake, endogenous synthesis capacity, and fatty acid trafficking. Higher circulating EPA is associated with favorable anti-inflammatory profiles and cardiometabolic markers in population studies. Genetics influences how efficiently the body synthesizes and maintains plasma EPA, particularly through the rate-limiting enzymes of the omega-3 fatty acid biosynthesis pathway.
The genetics behind plasma EPA levels
Genetic signals for plasma EPA levels concentrate in the chromosome 11q12 region, with the strongest associations near TMEM258, ELOVL2, FEN1, FADS1, and SYCP2L. The FADS gene cluster on chromosome 11q12-13 is the central genetic hub for long-chain polyunsaturated fatty acid levels, and most EPA genetic variation traces back to this region and associated enzymes.
TMEM258 encodes transmembrane protein 258, a component involved in N-glycosylation within the endoplasmic reticulum. Its strong association with EPA genetics (l2g score among the highest for this trait) reflects its location within the FADS locus—TMEM258 is physically adjacent to FADS1 and FADS2 on chromosome 11 and co-expressed with these desaturase enzymes. Fine-mapping studies have identified TMEM258 as a candidate causal gene in this region, distinct from FADS1/FADS2 themselves, suggesting a possible role in post-translational processing of the desaturase enzymes or in local cellular lipid homeostasis.
FADS1 encodes fatty acid desaturase 1, also known as delta-5 desaturase. This enzyme catalyzes the conversion of eicosatetraenoic acid (ETA, 20:4n-3) to EPA (20:5n-3)—the final desaturation step that produces EPA from shorter omega-3 precursors. FADS1 is therefore the most direct enzymatic determinant of EPA synthesis. Variants in FADS1 that reduce enzyme activity associate with lower endogenous EPA synthesis regardless of dietary ALA intake. The FADS1 and FADS2 genes operate in tandem: FADS2 (delta-6 desaturase) acts first in the pathway, converting ALA to stearidonic acid, while FADS1 completes the conversion to EPA further along.
The chromosome 11q12 FADS locus is the primary genetic determinant of omega-3 and omega-6 fatty acid levels across multiple populations. Variants near FADS1 and FADS2 explain a large fraction of the inter-individual variation in plasma EPA, DHA, and arachidonic acid (Lemaitre et al., 2011).
ELOVL2 encodes fatty acid elongase 2, which elongates EPA (20:5n-3) to DPA (docosapentaenoic acid, 22:5n-3) and subsequently contributes to DHA synthesis. In the context of plasma EPA levels, ELOVL2 acts as a downstream consumer of EPA—higher ELOVL2 activity directs more EPA toward elongation and eventual DHA production, potentially reducing the EPA pool available in plasma. Variants affecting ELOVL2 activity therefore influence circulating EPA partly by modulating how quickly EPA is elongated into longer-chain forms.
FEN1 encodes flap endonuclease 1, a DNA repair enzyme involved in Okazaki fragment processing during DNA replication. Its appearance in EPA genetics may reflect population-specific patterns of linkage disequilibrium identified in the Singaporean Chinese cohort, where certain chromosomal regions carry different haplotype structures than European populations, placing FEN1 in statistical proximity to functional omega-3 metabolism variants.
What the research says
Lemaitre et al. (2011) conducted a meta-analysis of genome-wide association studies for plasma phospholipid n-3 fatty acids, including EPA, across multiple European-ancestry cohorts. The study identified the FADS locus as the primary genetic determinant of EPA levels, with variants near FADS1 and FADS2 explaining substantial inter-individual variation. The findings established that omega-3 fatty acid levels are not merely determined by dietary intake—genetic differences in biosynthesis capacity contribute meaningfully.
Dorajoo et al. (2015) extended this work to a Singaporean Chinese population, examining n-3 and n-6 fatty acid genetics in an East Asian context. Cross-population replication of FADS locus associations confirmed their biological importance while identifying population-specific signals including FEN1. Together, these studies point to the omega-3 biosynthesis pathway as the primary genetic architecture for plasma EPA, with the FADS cluster at its center.
FADS1 and FADS2 variants are among the most functionally characterized genetic influences on long-chain omega-3 levels. Minor alleles reducing FADS1/FADS2 activity are associated with lower plasma EPA and DHA independent of dietary intake in multi-ethnic cohorts (Lemaitre et al., 2011; Dorajoo et al., 2015).
How EPA affects you
EPA functions as a direct precursor for eicosanoids—short-range signaling molecules that regulate inflammation, platelet aggregation, and vascular tone. The 3-series prostaglandins and 5-series leukotrienes derived from EPA have generally less pro-inflammatory activity than the arachidonic acid-derived 2-series and 4-series eicosanoids, which may partly explain the anti-inflammatory associations of higher omega-3 status. EPA also contributes to specialized pro-resolving mediators including E-series resolvins, which actively promote resolution of inflammatory responses rather than simply reducing their initiation.
Plasma EPA is part of the broader omega-3 index alongside DHA. Higher omega-3 index values are associated with favorable inflammatory markers and cardiometabolic profiles in population-level research. Because EPA and DHA work in complementary but distinct ways—EPA primarily through eicosanoid and resolvin pathways, DHA primarily through membrane incorporation and neuroprotectin pathways—their combined measurement provides a more complete picture of omega-3 status than either alone.
Working with your EPA profile
Dietary preformed EPA from fatty fish, fish oil, and algal oil bypasses the FADS1/FADS2 bottleneck entirely, directly supplying the active form. Individuals with reduced FADS1 activity variants benefit more from preformed EPA than from plant-sourced ALA, because ALA requires the FADS1 desaturation step to reach EPA. Regular fatty fish consumption (two or more servings per week) raises plasma EPA substantially in most individuals regardless of genetic background.
For those relying on plant-based omega-3 sources, ALA from flaxseed, chia, hemp, and walnuts provides EPA precursors, but conversion rates vary widely—influenced by FADS1/FADS2 genotype, dietary fat composition, and metabolic status. Monitoring the omega-3 index provides a functional measure of combined EPA and DHA status in red blood cell membranes, reflecting longer-term tissue incorporation beyond a single plasma measurement.
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Related traits and genes
Plasma EPA genetics substantially overlaps with DHA, DPA, and total omega-3 fatty acid traits through the shared FADS locus. ELOVL2 appears in both EPA and DHA genetics, reflecting its position between these two fatty acids in the synthesis cascade. FADS1 and FADS2 are among the most pleiotropic genes in fatty acid biology, with variants influencing the full spectrum of long-chain omega-3 and omega-6 fatty acid levels simultaneously. TMEM258, as a fine-mapped candidate in the FADS locus, represents an understudied component of the local regulatory architecture at chromosome 11q12.