<prompt> A patient was diagnosed with isolated increase in LDL. His father and brother had the same disease with increased cholesterol. The likely diagnosis is:Familial type III hyperlipoproteinemiaAbetalipoproteinemiaFamilial LPL deficiency type ILDL receptor mutation  <response>: Ans. D. LDL receptor mutationRef: Harrison 19e, Table 356.3Fredericksons Classification of HyperlipoproteinemiaPhenotypeType IType IIType IIIMolecular defectLipoprotein lipase apo CIILDL receptor defect apo B100 defective Apo E defectGenetic nomenclatureFamilial chylomicronemia syndromeFamilial Hypercholesterolemia Familial Defective apo BFamilial dysbetalipoproteinemiaClinical featuresEruptive Xanthoma Pancreatitis Lactescent Plasma No Coronary Peripheral AtherosclerosisTendon Xanthoma Tuberous Xanthoma No Pancreatitis No Lactescent Plasma Coronary atherosclerosisPeripheral Atherosclerosis Tuberoeruptive XanthomaNo Pancreatitis Coronary atherosclerosis Peripheral Atherosclerosis Lipid elevatedTriacylglycerol NB: Cholesterol normalCholesterolNB: Triacylglycerol normalCholesterol triacylglycerolLipoprotein elevatedChylomicronLDLChylomicron remnant VLDL remnant 