Williams syndrome, also known as Williams-Beuren syndrome, is a rare genetic disorder characterized by growth delays before and after birth (prenatal and postnatal growth retardation), short stature, a varying degree of mental deficiency, and dist...

What is pericarditis? The heart muscle has a tight covering that surrounds it, a lining sac called the pericardium (peri=around +cardium=heart). This sac actually has two layers. The visceral pericardium is only one cell layer thick and fi...