Serum lipoprotein and lymphocyte LDL receptor studies in parents and children with heterozygous familial hypercholesterolemia

In certain cases heterozygous familial hypercholesterolaemia (FH) cannot be confidently diagnosed from elevated serum lipid and lipoprotein values alone because of overlap with normal values. In the present study, therefore, lymphocyte high-affinity LDL receptor degradation of 125I-LDL was measured in 36 subjects from nine FH families. In eight families there was a good agreement between elevated serum lipid and lipoprotein values and reduced 125I-LDL degradation. In the ninth family, however, LDL receptor activity was normal in three subjects from three generations with elevated serum lipids and lipoproteins. The data suggest a disorder of LDL metabolism other than FH.