An autosomal recessive disorder of lipid metabolism. It is caused by mutation of the microsomal triglyceride transfer protein that catalyses 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.