PHACTR1 Variant (rs9349379)

Most genetic markers nudge your risk in one direction: higher or lower. This one does something unusual. PHACTR1 rs9349379 (phosphatase and actin regulator 1, single nucleotide polymorphism rs9349379) is a variant where each version of the gene raises the risk for one category of vascular disease while lowering the risk for another. Depending on your genotype, your arteries may be more prone to plaque buildup or more prone to tearing. Knowing which version you carry tells you which type of cardiovascular threat deserves your attention.

You inherit two copies of this variant, one from each parent. Each copy is either the "A" version or the "G" version. That gives you three possible combinations: A/A, A/G, or G/G. The direction of your risk depends entirely on which combination you have.

Why This Variant Matters: Two Opposing Risk Profiles

The G allele raises your risk for the kind of heart disease most people think of first: cholesterol-driven plaque building up inside artery walls, eventually causing a heart attack. If you carry two copies of G (G/G), your risk of coronary artery disease is moderately elevated (about 15% to 37% higher than A allele carriers, depending on the population studied). In one study of Chinese Han adults, G/G carriers had roughly 2.4 times the odds of coronary artery disease compared to other genotypes, with a stronger effect in women.

The A allele pushes risk the other direction. It is protective against plaque-driven heart disease (about 12% lower risk per copy). But it raises the odds of a different set of conditions where the artery wall itself is fragile. People carrying A alleles face higher risk for spontaneous coronary artery dissection (SCAD), a condition where the inner wall of a heart artery tears without warning. Each copy of the A allele increases SCAD risk by about 67%. They also face higher risk for fibromuscular dysplasia (FMD), a condition where artery walls develop abnormally, as well as cervical artery dissection and migraine.

This means that SCAD-related heart attacks and plaque-related heart attacks sit at opposite ends of a genetic spectrum. The biology driving one is fundamentally different from the biology driving the other. For young women especially, who make up the vast majority of SCAD and FMD cases, this variant can help clarify which type of vascular risk is most relevant.

How Each Genotype Shifts Your Risk

Your result will be one of three genotypes. Here is what each one means across the five vascular conditions linked to this variant.

Sources: Adlam et al. (2019); Gupta et al. (2017); Debette et al. (2015); Kasikara et al. (2021); Kiando et al. (2016); Chen et al. (2019).

What this means for you: If you carry A/A, your priority is awareness of arterial dissection and FMD, conditions that are underrecognized and often misdiagnosed, particularly in younger women with chest pain. If you carry G/G, the conventional playbook of managing cholesterol, blood pressure, and metabolic health applies with extra urgency. If you are A/G, you sit in the middle for both categories, which means standard cardiovascular vigilance without a strong tilt in either direction.

What Is Happening Inside Your Arteries

This variant sits inside the PHACTR1 gene, but its most important job is controlling a different gene about 600,000 DNA letters away: EDN1, which produces a powerful blood vessel constricting molecule called endothelin-1. In aortic tissue specifically, this variant acts like a volume dial for endothelin-1 production. The effects of endothelin-1 on blood vessel tone, wall remodeling, and blood pressure help explain why this single variant influences five different vascular conditions.

The G allele also lowers the activity of the PHACTR1 gene itself in immune cells called macrophages. Macrophages are responsible for cleaning up dying cells inside artery walls, a housekeeping process that keeps plaques from becoming dangerous. When PHACTR1 activity drops, macrophages become worse at this cleanup job. Dead cells accumulate, the plaque's protective cap thins, and the plaque becomes more likely to rupture and trigger a heart attack.

The A allele, meanwhile, is associated with more flexible, stretchy arteries. Both the ascending aorta (the large artery leaving your heart) and the carotid arteries (the arteries in your neck) show higher distensibility in A allele carriers. More flexible arteries resist plaque formation, but they may be structurally more vulnerable to tearing, which helps explain the increased dissection risk.

So the tradeoff comes down to artery wall character: stiffer walls (G/G) collect plaque; more compliant walls (A/A) are more likely to tear.

What You Can Do About Your Result

Because this is a genetic variant, your genotype does not change. You will always carry the same combination of A and G alleles. However, the clinical consequences of your genotype are not fixed. The diseases this variant influences are all shaped by modifiable risk factors, which means you can still shift your actual disease risk substantially.

If you carry the G/G genotype (higher atherosclerotic risk): The standard tools for preventing plaque-driven heart disease, including blood pressure control, lipid management, regular exercise, a diet low in processed foods, smoking cessation, and weight management, all reduce the risk that this genotype contributes to. Because the G allele promotes vulnerable plaque features through impaired macrophage function, aggressive management of the modifiable contributors to plaque instability is especially relevant. Discuss statin therapy and blood pressure targets with a clinician if you carry this genotype alongside other cardiovascular risk factors.

If you carry the A/A genotype (higher dissection and FMD risk): There are no targeted pharmacological interventions proven to prevent SCAD or FMD based on genotype alone. However, awareness matters. If you experience sudden, severe chest pain, especially as a younger woman, ensuring that your care team considers SCAD alongside the usual plaque-related diagnoses could be critical. People with FMD should also be evaluated for involvement in other vascular beds, since the condition can affect arteries throughout the body.

Questions This Biomarker Can Answer

• Is my genetic cardiovascular risk tilted more toward plaque buildup or toward artery wall fragility?
• Should I be aware of spontaneous coronary artery dissection as a potential cause if I ever have a cardiac event?
• Do I carry a genetic predisposition for fibromuscular dysplasia or cervical artery dissection?
• Does my genotype support being more aggressive about traditional atherosclerotic risk factor management?
• Is my migraine history potentially linked to a vascular genetic variant?