Cerebrotendinous xanthomatosis, sitosterolemia, Smith-Lemli-Opitz syndrome and the seminal contributions of Gerald Salen, MD (1935–2020)

•CTX causes neurologic disease which can be prevented with chenodeoxycholate.•Sitosterolemia causes premature ASCVD which can be prevented with ezetimibe.•SLOS causes mental disability which can be treated with diet and bile acids.•Gerald Salen (1935–2020) developed treatments for CTX, sitosterolemia, and SLOS.