Fibromuscular dysplasia (FMD) is a non-atherosclerotic, non-inflammatory, sometimes fatal vascular disease. The mean age at diagnosis is ~50 years, and over 80 percent of patients are female. FMD may cause fibrosis (scarring), stenosis (narrowing), dissection (tearing), tortuosity (too many bends), aneurysm (dilation), and occlusion (blockage) of medium and large arteries throughout the body. More specifically, FMD commonly affects the renal arteries where it may cause high blood pressure, while cervical or carotid artery involvement can lead to stroke. While the incidence of clinically manifested FMD remains unclear, the true disease prevalence may be as high as five percent in women, though the majority experience no clinical problems.

Spontaneous Coronary Artery Dissection (SCAD) is closely related to FMD and specifically involves dissection (tearing) of the arteries that lead to the heart. While in some patients SCAD is very similar to sudden tearing of the cardiac arteries, in others it can manifest as a sudden bleed (hemorrhage) in the blood vessel wall. Additionally, during SCAD a blood clot can arise inside the blood vessel, or a major hemorrhage in the artery wall can “squeeze” the artery closed. Both mechanisms block the arteries leading to the heart and thus produce a heart attack. Like FMD, SCAD predominantly affects women, and most cases occur in mid-life. Some SCAD events are also associated with the weeks leading up to and immediately after childbirth (i.e. the peri-partum and post-partum periods). Of patients with SCAD, ~50 percent also have FMD.

Working with International collaborators, we have successfully identified several genes involved in both FMD and SCAD. Indeed, the very first of these identified genes, PHACTR1, has been linked to both diseases. While we have a long way to go, by better understanding the causes of FMD and SCAD, we hope to one day be able to develop specific therapies for them.