Sterol concentrations in cultured Smith-Lemli-Opitz syndrome skin fibroblasts: Diagnosis of a biochemically atypical case of the syndrome

Akira Honda, G. Stephen Tint, Gerald Salen, Richard I. Kelley, Megumi Honda, Ashok K. Batta, Thomas S. Chen, Sarah Shefer

Research output: Contribution to journalArticlepeer-review

Abstract

The Smith-Lemli-Opitz syndrome is a common birth defect syndrome caused by a deficiency of 7-dehydrocholesterol Δ7-reductase, an essential enzyme in the biosynthesis of cholesterol. The syndrome can usually be diagnosed easily from the plasma markers of markedly elevated 7-dehydrocholesterol and reduced cholesterol concentrations. However, atypical cases with normal plasma levels of cholesterol with only moderately elevated 7- dehydrocholesterol have been reported. To establish a sensitive method for the biochemical diagnosis of the atypical cases of the syndrome, we measured sterol concentrations of cultured skin fibroblasts. 7-Dehydrocholesterol concentrations in patients' fibroblasts grown in the presence of 10% fetal bovine serum were significantly higher than those in controls and parents (P < 0.0005), but they were not elevated proportionately as much as in plasma. To re-produce the accumulation of 7-dehydrocholesterol, the cells were exposed to delipidated medium to induce sterol biosynthesis. After 4 weeks, 7-dehydrocholesterol concentrations in patients' fibroblasts increased from 2.8 ± 0.3% to 34 ± 3% of total sterols (cholesterol + 7-dehydrocholesterol + 8-dehydrocholesterol). The increase was also observed in fibroblasts from an atypical patient who has a normal plasma cholesterol level and a 7- dehydrocholesterol concentration of only 0.15 mg/dl. In contrast, cells from parents and controls accumulated very little 7-dehydrocholesterol (<1% of total sterols). These results demonstrate that cultured fibroblasts exhibit abnormally high accumulation of 7-dehydrocholesterol after cells are exposed to delipidated medium not only in typical patients, but also in an atypical case. The present method is a sensitive procedure for the biochemical diagnosis of this syndrome.

Original languageEnglish (US)
Pages (from-to)282-287
Number of pages6
JournalAmerican journal of medical genetics
Volume68
Issue number3
DOIs
StatePublished - 1997

Keywords

  • 7-dehydrocholesterol
  • 8- dehydrocholesterol
  • Smith-Lemli-Opitz syndrome
  • skin fibroblast

ASJC Scopus subject areas

  • Genetics
  • Genetics(clinical)

Fingerprint

Dive into the research topics of 'Sterol concentrations in cultured Smith-Lemli-Opitz syndrome skin fibroblasts: Diagnosis of a biochemically atypical case of the syndrome'. Together they form a unique fingerprint.

Cite this