rs2070699 — EDN1 EDN1 G2288T Intronic Variant

EDN1 G2288T — The Endothelin Dial and Vascular Risk

Endothelin-1 (ET-1), encoded by the EDN1 gene on chromosome 6, is the most potent endogenous vasoconstrictor known. It is produced primarily by vascular endothelial cells and acts on smooth muscle to contract blood vessels, regulate blood pressure, and modulate vascular tone across virtually every major vascular bed — pulmonary, coronary, cerebral, and renal. ET-1 exerts its effects through two G-protein-coupled receptor subtypes: ETA¹¹ ETA
endothelin receptor type A, expressed on smooth muscle, mediating sustained vasoconstriction and ETB, expressed on endothelial cells, mediating vasodilation and ET-1 clearance. The balance between ET-1 production and receptor activation is a major determinant of vascular resistance, and genetic variants that shift ET-1 output upward carry measurable cardiovascular consequences.

The Mechanism

The rs2070699 variant sits 30 nucleotides into an intron of EDN1 at chr6:12292539 (GRCh38), positioned downstream of exon 2. The functional consequence is regulatory rather than protein-altering: the G-to-T substitution falls within a conserved intronic region that influences pre-mRNA processing and EDN1 transcript abundance. The PPHN study²² The PPHN study
Mei et al. EDN1 Gene Variant is Associated with Neonatal Persistent Pulmonary Hypertension. Sci Rep. 2016 directly measured the downstream protein consequence: neonates carrying the T allele at rs2070699 had significantly higher circulating ET-1 levels (3.33 ± 2.52 pg/mL versus 1.22 ± 0.86 pg/mL; P=0.002), establishing that this intronic variant produces a measurable upregulation of ET-1 expression.

Higher ET-1 impairs vasodilation on multiple levels. It directly promotes smooth muscle contraction through ETA receptors, stimulates aldosterone secretion, activates platelet aggregation, and — critically — reduces bioavailable nitric oxide (NO) by competing with endothelium-derived vasodilatory signals. The NOx association documented by Gumanova et al. 2019³³ Gumanova et al. 2019
Gumanova et al. Levels of nitric oxide metabolites, adiponectin and endothelin are associated with SNPs of the adiponectin and endothelin genes. Biomed Rep. 2019 — rs2070699 associated with reduced nitric oxide metabolite levels in women, which in turn predicted cardiovascular mortality — captures this NO-ET-1 antagonism at the population level.

The Evidence

Neonatal pulmonary hypertension: The clearest mechanistic link comes from Mei et al. 2016⁴⁴ Mei et al. 2016
Mei M et al. EDN1 Gene Variant is Associated with Neonatal Persistent Pulmonary Hypertension. Sci Rep. 2016;6:29877, a study of 112 neonates (55 PPHN cases, 57 controls) with respiratory distress. The T allele appeared in 54.5% of PPHN cases versus 27.2% of controls (OR 3.89, 95% CI 1.96–7.72), with TT homozygotes showing the highest ET-1 levels and the longest mechanical ventilation requirements. This is the most direct evidence linking rs2070699 to elevated ET-1 production, as PPHN results specifically from failure of the pulmonary vasculature to dilate at birth — a process that requires ET-1 levels to fall.

Cerebrovascular hemorrhage: Foreman et al. 2017⁵⁵ Foreman et al. 2017
Foreman PM et al. Endothelin polymorphisms as a risk factor for cerebral aneurysm rebleeding following aneurysmal subarachnoid hemorrhage. Clin Neurol Neurosurg. 2017;157:65-69 prospectively followed 149 aSAH patients. The TT genotype emerged as an independent predictor of aneurysm rebleeding (OR 97.4, 95% CI 3.83–2480, P=0.006), with all five rebleed events occurring exclusively in TT carriers. While the sample is small (n=149) and the CI wide, this result survived multivariable adjustment and aligns biologically: elevated ET-1 promotes cerebral vasospasm and disrupts the vascular wall biology that normally prevents rebleeding.

Ischemic stroke (sex-specific): Zhang and Sui 2014⁶⁶ Zhang and Sui 2014
Zhang L, Sui R. Effect of SNP polymorphisms of EDN1, EDNRA, and EDNRB gene on ischemic stroke. Cell Biochem Biophys. 2014;70(3):1895-901 found that the G allele (not T) increased ischemic stroke risk in Northern Han Chinese males (OR 1.78, 95% CI 1.15–2.75, P=0.009) — a finding that was sex-specific (no association in females) and population-specific. This contradicts the direction seen in the PPHN and rebleeding studies and likely reflects a different downstream pathway or haplotype context in this population.

High-altitude physiology: Yu et al. 2020⁷⁷ Yu et al. 2020
Yu J et al. EDN1 gene potentially involved in the development of acute mountain sickness. Sci Rep. 2020;10:5397 followed 356 male soldiers ascended to 3,700m, of whom 67% developed acute mountain sickness. The T allele positively correlated with AMS occurrence, with rs2070699 surviving as an independent predictor in multivariate analysis alongside mean arterial pressure, oxygen saturation, and lung function. ET-1 is upregulated in hypoxia, and genetically elevated ET-1 may impair the hypoxic vasodilatory response in pulmonary and cerebral vasculature.

Practical Actions

For TT homozygotes, the most actionable implication is monitoring of ET-1-dependent vascular phenotypes. In clinical settings — particularly pulmonary hypertension, cerebrovascular disease, or high-altitude exposure — the TT genotype provides context for elevated cardiovascular reactivity. Endothelin receptor antagonists (bosentan, ambrisentan, macitentan) are now standard therapy for pulmonary arterial hypertension, and knowledge of rs2070699 genotype may inform clinical index of suspicion.

Nitric oxide precursors (L-arginine, L-citrulline) and dietary nitrates (beetroot, leafy greens) support endogenous NO production, directly counteracting ET-1-mediated vasoconstriction at the vascular endothelium. This is mechanistically targeted for T allele carriers whose vascular tone is biased toward the ET-1 (vasoconstrictive) side of the ET-1/NO balance.

Interactions

The EDN1 system interacts with the nitric oxide pathway at multiple levels. Variants in NOS3 (endothelial nitric oxide synthase, rs1799983) that reduce eNOS activity act in the same vasoconstriction-promoting direction as elevated ET-1. Carriers of both elevated-ET-1 (rs2070699 T allele) and reduced-eNOS (NOS3) variants may have compounded vascular tone dysregulation.

rs2070699 is in partial linkage disequilibrium with the functionally important EDN1 rs5370 (Lys198Asn missense variant, which alters ET-1 receptor binding affinity) and rs1800543 (promoter variant affecting basal EDN1 transcription). The Foreman 2017 aSAH study genotyped both rs2070699 and the broader EDN1/EDNRA/EDNRB locus, suggesting haplotype context — not just rs2070699 in isolation — may be the most informative unit for cerebrovascular risk prediction.