Prenatal diagnosis of Smith-Lemli-Opitz syndrome is possible by measurement of 7-dehydrocholesterol in amniotic fluid

Prenat Diagn. 1995 Sep;15(9):855-8. doi: 10.1002/pd.1970150911.


Amniocentesis was performed at 17.3 weeks in a pregnancy with severe intrauterine growth retardation. Cytogenetic studies on amniocytes were normal, 46,XX, and the pregnancy was continued. The diagnosis of Smith-Lemli-Opitz syndrome was suspected in the neonatal period and confirmed by the presence of 7-dehydrocholesterol (7-DHC) in the plasma (0.4 mmol/l, normal = not detectable) associated with a low total cholesterol concentration (0.4 mmol/l, normal = 2.56 +/- 0.23). Retrospective analysis of the amniotic fluid sample revealed an elevated level of 7-DHC (0.022 mmol/l; normal = undetectable). Therefore measurement of 7-DHC levels in amniotic fluid during the second trimester of pregnancy is useful for the prenatal diagnosis of Smith-Lemli-Opitz syndrome in families at risk and should be considered in cases of severe growth retardation of unknown aetiology for which amniotic fluid is available and in which a normal chromosomal pattern in amniocytes is present.

Publication types

  • Case Reports

MeSH terms

  • Adult
  • Amniocentesis*
  • Amniotic Fluid / chemistry*
  • Cholesterol / blood
  • Chromatography, Gas
  • Dehydrocholesterols / analysis*
  • Dehydrocholesterols / blood
  • Female
  • Fetal Growth Retardation / etiology
  • Humans
  • Mass Spectrometry
  • Pregnancy
  • Pregnancy Trimester, Second
  • Smith-Lemli-Opitz Syndrome / diagnosis*
  • Smith-Lemli-Opitz Syndrome / metabolism


  • Dehydrocholesterols
  • Cholesterol
  • 7-dehydrocholesterol