This disease is genetic and inherited, although the specific defective genes have not been identified. The person's cholesterol or triglyceride levels become elevated during the teenage years and continue throughout life. The types of elevated lipoproteins may vary between affected family members.

Cholesterol deposits in the skin, called xanthomas, which are seen in other disorders of elevated lipoproteins are rarely seen in this disorder. This disorder predisposes the person to greater risk of early coronary artery disease and therefore, heart attacks. People with the condition have a higher rate of obesity and glucose intolerance.

The condition is worsened by diabetes, alcoholism, and hypothyroidism. Risk factors are a family history of high cholesterol and early coronary artery disease. This is the most common disorder of increased blood fats that causes early heart attacks. The rare person who gets 2 defective genes is at much higher risk for early heart attack due to very high blood fat (cholesterol or triglyceride) levels.