Dr. Brown co-discovered the low-density lipoprotein (LDL) receptor, which controls cholesterol in the blood and in cells. He showed that mutations in this receptor cause familial hypercholesterolemia, a disorder that leads to premature heart attacks. His work laid the groundwork for drugs called statins, which block cholesterol synthesis, increase LDL receptors, lower blood cholesterol, and prevent heart attacks. Statins are taken daily by more than 20 million people worldwide.