Identification of 19-nor-5,7,9(10)-cholestatrien-3 beta-ol in patients with Smith-Lemli-Opitz syndrome.

We have identified the third unknown sterol in the plasma and tissues of Smith-Lemli-Opitz homozygotes as 19-nor-5,7,9(10)-cholestatrien-3 beta-ol. The structure was established from capillary gas-liquid chromatography retention index and characteristic fragmentation pattern by mass spectrometry that were identical to a synthetic reference standard. Evidence is presented that 19-nor-5,7,9(10)-cholestatrien-3 beta-ol is not an artifact formed during the chemical isolation of the relatively unstable 7-dehydrocholesterol. It is possible that 19-nor-5,7,9(10)-cholestatrien-3 beta-ol may contribute to the clinical abnormalities in patients with Smith-Lemli-Opitz syndrome.