Tangier disease with normal serum cholesterol

Three patients with Tangier Disease (hypoalphalipoproteinaemia) from the same family are described. One shows the classically described lipid abnormalities of the disease, with a low serum cholesterol level, and almost absent high density lipoprotein (HDL). However, two of his siblings, although demonstrable as Tangier homozygotes, have serum cholesterol levels within the normal range. This anomaly has arisen because they are also heterozygous for familial combined hyperlipidaemia. The pattern of inheritance of the two disorders, Tangier Disease and combined hyperlipidaemia, appears to be unrelated.