Type III hyperlipoproteinemia is a genetic disorder characterized by the accumulation of abnormal lipoproteins in the blood, specifically chylomicron remnants and very low-density lipoproteins (VLDL). This condition often leads to elevated levels of cholesterol and triglycerides, increasing the risk of cardiovascular diseases. The disorder is commonly associated with mutations in the ApoE gene, which plays a crucial role in lipid metabolism. Symptoms may include xanthomas, which are fatty deposits in the skin, and an increased risk of atherosclerosis. Diagnosis typically involves blood tests to measure lipid levels and genetic testing for confirmation.