APOA1 and Tangier disease: Compound homozygous or heterozygous mutations in the ABCA1 gene cause Tangier disease (TGD) (OMIM, 205,400), a rare autosomal recessive disorder characterized by extremely low plasma HDL-C levels (HDL-C < 5 mg/dL) and ApoA- I ≤ 10 mg/dL and, increased risk of early-onset CAD [16].