Homozygous familial hypercholesterolemia is a rare disorder characterized by severely elevated total cholesterol and LDL cholesterol levels, leading to premature atherosclerotic plaque formation in arteries, increasing the risk of cardiovascular disease and death. Xanthomas in the skin and tendons are common. The condition is associated with genetic changes in the LDLR gene and is inherited in an autosomal dominant manner. Other hereditary forms of hypercholesterolemia can be caused by genetic changes in the APOB, LDLRAP1, or PCSK9 gene. Lifestyle choices and genetic variations can also contribute to high cholesterol levels.