rs17301739 — LIPC

LIPC — The Hepatic Lipase Gene and Your DHA Status

Hepatic lipase (HL), encoded by LIPC, is a multifunctional enzyme produced by liver cells and secreted into the bloodstream. It hydrolyzes triglycerides and phospholipids in circulating lipoproteins — especially HDL and IDL — playing a dual role in HDL remodeling and in generating a specific lysophosphatidylcholine-DHA¹¹ lysophosphatidylcholine-DHA
LPC-DHA: a water-soluble form of docosahexaenoic acid that crosses the blood-brain barrier via the dedicated Mfsd2a transporter (LPC-DHA) that is the preferred molecular carrier of DHA into the brain.

rs17301739 is an intronic variant in LIPC that GWAS studies have linked at genome-wide significance to circulating DHA and total omega-3 fatty acid levels. Carriers of the G allele show measurably higher plasma DHA and omega-3/omega-6 ratios, pointing to altered hepatic lipase expression or activity in the liver's phospholipid processing pathway.

The Mechanism

Hepatic lipase cleaves the sn-2 position of phosphatidylcholine on HDL particles, releasing fatty acids including DHA as lysophosphatidylcholine (LPC). This LPC-DHA form is then transported via albumin to the blood-brain barrier, where the Mfsd2a transporter actively imports it — a more efficient route than passive diffusion of unesterified DHA. As a result, hepatic lipase activity is a key determinant of how much DHA reaches the brain.

Mouse knockout studies²² Mouse knockout studies
Sugasini et al. Potential role of hepatic lipase in the accretion of docosahexaenoic acid (DHA) by the brain. Biochim Biophys Acta, 2021 showed that HL-deficient mice had 19% lower brain DHA compared to controls, and combined HL+EL deficiency dropped brain DHA by 55% — establishing HL as the dominant source of plasma LPC-DHA.

The rs17301739 intronic variant is located at c.88+6320 in the LIPC transcript, placing it deep in intron 1. Intronic variants at this depth most often act through effects on transcription factor binding sites, splicing regulatory elements, or long-range enhancer activity. The functional mechanism of rs17301739 specifically has not been characterized in a cell-based study, but its genome-wide significant associations with circulating omega-3 levels confirm it tags a functionally relevant regulatory element.

The Evidence

A large-scale GWAS of plasma fatty acid composition³³ of plasma fatty acid composition
Sun Y et al. GWAS of plasma lipidome identifies genetic associations with omega-3 fatty acid levels. GWAS Catalog GCST90501978, 2025 identified rs17301739-G as associated with higher circulating DHA (p=4×10⁻¹⁵), higher total omega-3 fatty acid levels (p=1×10⁻¹⁴), and a higher omega-3/omega-6 ratio (p=2×10⁻⁹) — all at genome-wide significance with the G allele as the beneficial allele.

Separately, a GWAS of cognitive decline rate in Alzheimer's disease⁴⁴ GWAS of cognitive decline rate in Alzheimer's disease
Sherva et al. Genome Wide Association Study of the Rate of Cognitive Decline in Alzheimer's Disease. Alzheimer's & Dementia, 2013 (303 AD discovery cases; 323 replication cases) reported that rs17301739-G carriers declined more slowly (β=0.28, p=1.45×10⁻⁶). This finding is below genome-wide significance and did not achieve independent replication in the same paper, so it is treated here as emerging-level evidence for the cognitive benefit. The biological plausibility is strong given that DHA is critical for synaptic membrane integrity and that hepatic lipase is the primary generator of brain-accessible LPC-DHA.

The LIPC locus as a whole has multiple independent signals for HDL cholesterol and triglycerides. Five tagging LIPC SNPs show independent and additive effects of 1.5–5.2 mg/dL on HDL-C in European cohorts. Hodoglugil et al.⁵⁵ Hodoglugil et al.
Hodoglugil et al. Polymorphisms in the hepatic lipase gene affect plasma HDL-cholesterol levels in a Turkish population. J Lipid Res, 2010 established this dose-dependent effect in over 3,700 subjects. rs17301739 is a distinct intronic signal in the same gene region, associating specifically with circulating omega-3 indices rather than total HDL-C, consistent with its position in a different LD block from the classical promoter variants.

Practical Actions

For CC genotype carriers (the majority), circulating DHA production from LIPC phospholipid hydrolysis proceeds at the population-average rate. Dietary omega-3 intake remains the most effective lever: consuming pre-formed DHA from fatty fish or algae-based supplements provides DHA directly, bypassing any LIPC efficiency constraint.

For G allele carriers, enhanced LIPC-mediated LPC-DHA generation suggests that dietary phospholipid-bound DHA (from sources like krill oil or fish roe, which are phospholipid-rich rather than triglyceride-rich) may be especially well utilized — the substrate is already in the form hepatic lipase processes.

Interactions

This variant interacts conceptually with FADS1 (rs174550) and FADS2 variants, which govern the conversion of plant-derived ALA to EPA and DHA. A CC carrier who also has reduced FADS1/FADS2 conversion activity faces a double constraint: limited endogenous DHA synthesis AND population-average LIPC-mediated LPC-DHA generation. The practical advice converges: prioritize pre-formed DHA from marine sources rather than relying on ALA conversion.

LIPC variants also interact with CETP (cholesteryl ester transfer protein) variants in determining HDL particle composition and size. The combined LIPC×CETP effect on HDL-C has been documented in Roma and Hungarian populations (MDPI Genes, 2020).