rs6008845 — PPARA PPARA intronic C/T

The Fenofibrate Genotype — Why Only One in Three People Responds

Fenofibrate¹¹ Fenofibrate
a fibric acid derivative drug prescribed to lower triglycerides, raise HDL, and reduce cardiovascular risk in people with atherogenic dyslipidemia has always been puzzling: large trials like ACCORD-Lipid showed that adding fenofibrate to statin therapy produces no average cardiovascular benefit. But "no average benefit" conceals a striking pharmacogenomic split. A variant at rs6008845 — a regulatory site near the PPARA gene on chromosome 22 — predicts with unusual precision which patients get a dramatic 51% reduction in heart attacks and strokes, and which get nothing at all.

The Mechanism

PPARA²² PPARA
Peroxisome Proliferator-Activated Receptor Alpha, a nuclear receptor that acts as a master switch for fatty acid oxidation, triglyceride clearance, and anti-inflammatory gene regulation in the liver, vascular wall, and heart is the direct molecular target of fenofibrate. When fenofibrate binds and activates PPARα, the receptor promotes fatty acid catabolism, lowers triglycerides and raises HDL, and simultaneously suppresses pro-inflammatory transcription factors (NF-κB, AP-1) through a process called transrepression — a mechanism directly relevant to plaque stabilization.

rs6008845 sits approximately 21 kb upstream of the PPARA transcription start site. dbSNP annotates it against a nearby uncharacterized transcript (LOC124905137), but GTEx eQTL analysis³³ GTEx eQTL analysis
expression quantitative trait locus data from hundreds of post-mortem tissue samples shows that rs6008845 is a significant cis-regulatory variant for PPARA expression across multiple tissues. The T allele (the GRCh38 reference) is associated with higher or more appropriately-regulated PPARA expression; the C allele appears to reduce it. This makes TT carriers the group in whom fenofibrate most effectively amplifies an already-primed PPARα response — rather than trying to activate a receptor that is intrinsically under-expressed.

In a remarkable mechanistic finding, the ACCORD-Lipid pharmacogenomics study showed that in TT homozygotes specifically, fenofibrate significantly reduced circulating levels of CCL11 (eotaxin)⁴⁴ CCL11 (eotaxin)
a pro-inflammatory chemokine that recruits eosinophils and contributes to vascular inflammation and atherogenesis (P for interaction = 0.003). This effect was absent in C-allele carriers — suggesting that the TT genotype enables fenofibrate to activate a specific anti-inflammatory PPARα pathway that is blunted or absent when the C allele reduces PPARA expression.

The Evidence

The primary pharmacogenomic discovery comes from Morieri ML et al. 2020⁵⁵ Morieri ML et al. 2020
PPARA Polymorphism Influences the Cardiovascular Benefit of Fenofibrate in Type 2 Diabetes: Findings From ACCORD-Lipid. Diabetes 69:771–783, a pre-specified pharmacogenomic analysis of the ACCORD-Lipid randomized controlled trial. The discovery cohort included 3,065 white patients with type 2 diabetes, all on background statin therapy, randomized to fenofibrate or placebo. TT homozygotes (36% of white participants) experienced a 51% reduction in MACE (major adverse cardiovascular events): hazard ratio 0.49 (95% CI 0.34–0.72). CT and CC carriers showed zero cardiovascular benefit. The genotype-by-treatment interaction p-value was 3.7 × 10⁻⁴, exceeding pre-specified study-wide significance. Critically, the TT benefit persisted even in patients without classical atherogenic dyslipidemia (low HDL, high triglycerides), suggesting a lipid-independent mechanism — likely the CCL11 anti-inflammatory pathway.

Replication in African Americans within ACCORD (N=585) confirmed the same direction (P=0.02). Three external cohorts (ACCORD-BP, ORIGIN, TRIUMPH; combined N=3,059) replicated the interaction (P=0.005). Total replication sample size: 6,709 participants across four independent populations.

A contrasting finding came from Januszewski et al. 2026⁶⁶ Januszewski et al. 2026
FIELD trial substudy. Diabetes Res Clin Pract 234:113168 analyzing 8,159 participants over five years. Here fenofibrate reduced microvascular and macrovascular events consistently regardless of rs6008845 genotype (HR 0.79–0.87, all P<0.02), with no treatment-by-genotype interaction. The FIELD trial also found that T-allele carriers had somewhat higher baseline microvascular risk (HR 1.15 for TT vs CC). The discordance between ACCORD-Lipid and FIELD may reflect differences in study design (background statin vs no statin), statistical power, or phenotype definitions. The ACCORD finding is the larger and more precisely powered pharmacogenomic analysis with prospectively defined endpoints.

Evidence level: strong — replicated in five independent cohorts with a mechanistic CCL11 pathway identified, but full clinical guideline incorporation has not yet occurred.

Practical Actions

For CC and CT carriers on statin therapy, the ACCORD-Lipid data suggest that adding fenofibrate to statin therapy for cardiovascular protection alone is unlikely to be beneficial. The established approach — statin therapy first, with fibrate considered if atherogenic dyslipidemia persists — remains appropriate, but the pharmacogenomic data sharpen expectations: fibrates may improve the lipid profile without translating to cardiovascular event reduction in C-allele carriers. Targeting triglycerides below 150 mg/dL and raising HDL through omega-3 supplementation and dietary fat optimization remains relevant regardless of genotype.

For TT carriers, the data support discussing fenofibrate eligibility with a prescriber specifically for cardiovascular protection — even without classic dyslipidemia — when type 2 diabetes is present. The CCL11/eotaxin mechanism suggests the benefit is partly anti-inflammatory, not purely lipid-mediated, so lipid panels alone do not capture the full pharmacogenomic benefit signal.

Interactions

rs6008845 should be interpreted alongside other PPARA functional variants. The coding variant rs1800206 (Leu162Val) directly alters PPARα's ligand-binding domain and affects both spontaneous cardiovascular risk and fibrate lipid response. The intronic variant rs4253623 associates with myocardial infarction risk in a single study. The intron 7 variant rs4253778 affects PPARα expression in cardiac and muscle tissue during exercise. None of these variants are in strong linkage disequilibrium with rs6008845, so they represent independent functional signals; a person may carry multiple PPARA variants with additive or independent effects on PPARα biology.

Omega-3 fatty acids (EPA and DHA) are direct PPARα ligands that activate the receptor regardless of rs6008845 genotype, and may partially compensate for any C-allele-mediated reduction in PPARA expression by providing supraphysiological receptor activation.