Fibromuscular dysplasia (FMD) accounts for a significant fraction of renal artery stenosis. The distinction between fibromuscular dysplasia and atherosclerotic renal artery stenosis is important as the former tends to respond much more readily to interventional therapy than the latter. More specifically, FMD tends to respond favorably to balloon angioplasty.
There is some suggestion that FMD has a genetic component to it, though no gene has yet been identified. The diagnosis is usually made by angiography showing a “beads on a string” pattern in the affected artery. FMD can affect arteries other than just the renal arteries (e.g. the carotid arteries), but the disease is most famous for its effect on the renal arteries where it may cause secondary hypertension due to activation of the renin-angiotensin system.