An autosomal recessive disorder of Lipid Metabolism. It is caused by Mutation of the microsomal triglyceride Transfer protein that catalyzes the transport of Lipids (TRIGLYCERIDES; Cholesterol Esters; Phospholipids) and is required in the Secretion of beta-Lipoproteins (Low Density Lipoproteins or LDL). Features include defective intestinal lipid Absorption, very low Serum Cholesterol level, and near absent LDL.