rs854571 — PON1 PON1 -108C>T promoter variant

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.