Sitosterolemia (OMIM#210250), is a very rare inherited sterol storage disease caused by mutations in the adenosine triphosphate-binding cassette (ABC) transporter genes ABCG5 and ABCG8, which are located on chromosome 2p21 and expressed at the membrane of enterohepatic cells [76-78]. The gene discussed is ABCG5; the disease is sitosterolemia.