rs854571 — PON1 PON1 -108C>T promoter variant

Promoter variant that controls PON1 transcription; the T allele reduces PON1 expression by ~2-fold, lowering the anti-atherogenic enzyme activity on HDL particles and increasing vulnerability to LDL oxidation

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PON1 -108C>T — The Promoter Switch That Controls Your HDL's Antioxidant Power

Every HDL particle in your bloodstream carries a small but critical passenger: paraoxonase-1 (PON1), an enzyme that acts as the anti-atherosclerotic arm of your "good cholesterol." PON1 prevents LDL from oxidizing — the first step in plaque formation — and hydrolyzes lipid peroxides11 lipid peroxides
Oxidized lipid molecules that accumulate in arterial walls and drive foam cell formation and atherosclerotic plaque growth before they can damage arterial walls. The rs854571 variant is a single-letter switch in PON1's promoter region that determines how much enzyme your liver makes in the first place. Carriers of the T allele produce substantially less PON1, leaving their HDL with reduced antioxidant firepower.

The Mechanism

The rs854571 polymorphism lies approximately 108 base pairs upstream of the PON1 coding sequence on chromosome 7q21.3, within a region predicted to contain an SP1 transcription factor binding site22 SP1 transcription factor binding site
SP1 is a ubiquitous transcription factor that binds GC-rich sequences to activate gene expression in many tissue types. The C allele at this position appears to favor SP1 binding and active transcription; the T allele disrupts this interaction, reducing PON1 mRNA production.

Functional studies by Brophy, Jarvik, Furlong and colleagues33 Brophy, Jarvik, Furlong and colleagues
Brophy VH et al., Pharmacogenetics 2001 demonstrated that the -108, -162, and -909 promoter polymorphisms each exert approximately a two-fold effect on PON1 expression in reporter gene assays, with context-dependent non-additive interactions between them. The -108C/T variant alone accounted for 22.8% of the total observed variability44 22.8% of the total observed variability
Brophy VH et al., Am J Hum Genet 2001 in plasma PON1 activity across 376 white individuals — a larger share than the more commonly studied coding variants L55M and Q192R. Individuals homozygous for the high-expression haplotype (-108CC/-162AA) had a mean arylesterase activity of 140.9 U/ml, more than double the 67.5 U/ml seen in -108TT/-162GG homozygotes (P<0.001).

The -108 variant's effect is propagated through epigenetic regulation. Huen et al. (2015)55 Huen et al. (2015)
Environmental Epigenetics found that the -108 genotype was strongly associated with differential methylation at CpG sites flanking the CpG island in the PON1 promoter, and that increased methylation at these sites correlated with significantly decreased arylesterase activity — explaining how this promoter SNP shapes long-term expression even in the context of changing environmental exposures.

The Evidence

The consequences of lower PON1 expression extend well beyond the cardiovascular system. With reduced PON1 on HDL, there is less capacity to hydrolyze homocysteine thiolactone66 homocysteine thiolactone
A reactive sulfur compound generated during homocysteine metabolism; PON1 is the primary enzyme responsible for its detoxification in plasma and oxidized phospholipids, increasing systemic oxidative burden.

In a Swedish Parkinson's disease case-control study, Belin et al. (2012)77 Belin et al. (2012)
Neuroscience Letters found rs854571 significantly associated with PD protection (p=0.007). The minor T allele was more common among PD cases than controls, consistent with the hypothesis that higher PON1 levels — conferred by the C allele — reduce neuroinflammatory and oxidative stress vulnerability. This finding is strengthened by rs854571's strong linkage disequilibrium with rs854572, a variant independently reported to increase PON1 gene expression.

In dementia research, Bednarska-Makaruk et al. (2013)88 Bednarska-Makaruk et al. (2013)
Folia Neuropathologica found that T allele carriers were significantly over-represented in Alzheimer's disease patients versus controls, and multivariate regression confirmed a significant association between the -108C>T genotype and reduced arylesterase activity — exactly the direction predicted by the promoter function studies.

The -108C>T variant forms part of the extended PON1 promoter haplotype. Because PON1 expression level determines the quantity of enzyme loaded onto HDL particles, this promoter variant upstream modulates the functional impact of the downstream coding variants Q192R (rs662) and L55M (rs854560). Individuals carrying TT at rs854571 plus unfavorable coding variants face a compounded reduction in total effective PON1 activity.

Practical Actions

The practical implication of lower PON1 expression is reduced intrinsic protection against LDL oxidation — the key initiating step in atherosclerotic plaque formation. Dietary polyphenols (from berries, extra virgin olive oil, pomegranate, green tea) have been shown in multiple studies to partially compensate for lower PON1 activity by providing exogenous antioxidant capacity and by upregulating PON1 expression through independent pathways. For TT carriers, optimizing dietary polyphenol intake is a high-leverage strategy.

HDL particle quality monitoring — including PON1 arylesterase activity testing, which is available at specialized lipid clinics — is more informative than standard HDL cholesterol for TT and CT carriers, since a normal HDL-C level can coexist with significantly reduced antioxidant function.

Interactions

The rs854571 promoter variant operates within a three-variant PON1 haplotype that includes rs854560 (L55M, affects PON1 protein stability and serum concentration) and rs662 (Q192R, affects enzyme catalytic specificity). The promoter variant determines total enzyme output; L55M modulates protein stability; Q192R determines which substrates the available enzyme can efficiently process. Individuals carrying the TT promoter variant alongside 55M homozygosity (rs854560) and 192R homozygosity (rs662) represent the lowest-activity PON1 haplotype and carry the most significant atherosclerotic risk from this pathway.

rs854572, the immediately adjacent promoter variant at position 95,325,384 (GRCh38), is in strong linkage disequilibrium with rs854571 and has been independently associated with increased PON1 expression; these two variants are co-inherited on high-expression haplotypes in most European populations.

Nutrient Interactions

polyphenols altered_metabolism

Genotype Interpretations

What each possible genotype means for this variant.

CC High PON1 Expresser Normal

High PON1 promoter activity — optimal HDL antioxidant enzyme levels

You carry two copies of the C allele at rs854571, the common high-expression variant found in approximately 48% of people globally (about 72% in Europeans and East Asians). Your PON1 promoter drives robust transcription of the paraoxonase-1 gene in the liver, resulting in high levels of the enzyme loaded onto HDL particles. Studies show CC homozygotes for the high-expression PON1 promoter haplotype have mean arylesterase activity more than twice that of the low-expression TT genotype. This provides strong intrinsic protection against LDL oxidation and atherosclerotic plaque initiation.

CT Intermediate PON1 Expresser Intermediate

One low-expression allele — moderately reduced PON1 output

The -108C>T promoter polymorphism exerts roughly a two-fold effect on PON1 expression. In heterozygotes, one allele drives full transcription while the other is dampened, producing an intermediate phenotype. Population studies show this intermediate activity phenotype is associated with modestly elevated susceptibility to LDL oxidation compared to CC carriers, though the effect is smaller than in TT homozygotes.

The clinical significance is most apparent in the context of additional PON1 coding variants. If you also carry low-activity variants at Q192R (rs662) or L55M (rs854560), the combined effect on your total PON1 activity may be larger than this promoter variant alone would suggest.

TT Low PON1 Expresser Reduced

Both copies carry the low-expression allele — significantly reduced PON1 enzyme output

The -108C>T promoter variant sits adjacent to a predicted SP1 transcription factor binding site. When two T alleles are present, PON1 transcription is substantially dampened across both chromosomes, creating a chronic deficit in liver-derived PON1 synthesis. Since PON1 is loaded exclusively onto HDL particles after secretion — not stored in cells — the transcriptional deficit directly reduces how much anti-atherogenic enzyme circulates in the bloodstream.

Lower circulating PON1 means reduced capacity to hydrolyze lipid peroxides on LDL and HDL, less homocysteine thiolactone detoxification, and diminished hydrolysis of oxidized phospholipids in early atherosclerotic lesions. These functions are the primary reason PON1 is considered anti-atherogenic despite being a passenger on HDL rather than a structural component.

Association studies consistently show T allele carriers are over-represented in disease groups where oxidative burden is central: Parkinson's disease (p=0.007 in Belin 2012), Alzheimer's disease (Bednarska-Makaruk 2013), and in populations with elevated cardiovascular oxidative stress. The mechanism is the same in each case — insufficient PON1 to neutralize reactive lipid species before they damage tissues.

The TT promoter genotype compounds with coding variants. If you also carry the 192R allele at rs662 (lower LDL antioxidant activity) or the 55M allele at rs854560 (lower protein stability and serum concentration), your combined PON1 activity may be severely reduced, placing you in the highest-risk PON1 haplotype group.