A non-classical presentation of tangier disease with three ABCA1 mutations

Abstract

Tangier disease is a very rare autosomal recessive inherited disorder characterized by markedly reduced high-density lipoprotein (HDL) levels, characteristic large, yellow–orange tonsils, and enlarged liver, spleen and lymph nodes. It is caused by mutations in the ABCA1 gene. There is no specific treatment, and medications traditionally used to increase HDL are ineffective. A number of patients with non-classical Tangier disease have been described in the literature, who presented with low HDL levels, corneal lesions, hepatosplenomegaly, and thrombocytopenia. We report here about a 45-year-old female with a past medical history of early coronary artery disease, myocardial infarction, multiple episodes of angina, immeasurable HDL, and a history of idiopathic thrombocytopenia purpura. She had a tonsillectomy performed previously, but did not remember if the tonsils were of any unusual color. There was no history of peripheral neuropathy. Her family history is significant for her father and mother having Alzheimer disease and hypertension, respectively. On physical examination she did not have any hepatosplenomegaly or corneal opacities. She was found to have three mutations in the ABCA1 gene. These were designated A1046D (c.3137C>A) in exon 22; Y1532C (c.4595A>G) in exon 34, and W1699C (c.5097G>T) in exon 37. All three have been reported to be deleterious in functional studies. The patient has immeasurable HDL, which leads us to assume that two mutations are on one allele and one mutation on the other. We suspect that this condition is under-diagnosed, and as more patients are reported in the literature, the phenotype of Tangier disease will be elucidated further.