<prompt> A patient was diagnosed with an isolated increase in LDL. His father and brother had the same disease with increased cholesterol. The likely diagnosis isFamilial type III hyperlipoproteinemiaAbetalipoproteinemiaFamilial lipoprotein lipase deficiency type 1LDL receptor mutation  <response>: LDL receptor mutation Isolated increase in LDL with positive family history suggests the diagnosis of familial hypercholesterolemia.Familial hypercholesterolemia type IIa is due to deficiency of functional LDL receptors as a result of different types of mutations. 