Tangier disease is an extremely rare autosomal recessive disorder caused by a mutation in the ATP-binding cassette transporter A1 (ABCA1) gene, which plays an important role in cholesterol transport. The mutation leads to severe high-density lipoprotein (HDL) deficiency and accumulation of cholesterol and lipids in various tissues. About 100 cases have been documented worldwide.

Clinical signs include enlarged orange tonsils (from deposition of cholesterol ester), neuropathy, hepatosplenomegaly, lymphadenopathy, corneal opacities, and premature atherosclerosis resulting in early cardiovascular disease in adulthood.

While HDL deficiency may be noted incidentally early in life, affected children are most often diagnosed due to enlarged orange tonsils. Patients diagnosed in adulthood have presented with neuropathy or clinical features resulting from hepatosplenomegaly, premature cardiovascular disease, or other signs and symptoms.