Several studies have demonstrated a high incidence of autistic spectrum features in individuals with Smith-Lemli-Opitz syndrome (SLOS). However, do these findings imply a converse relationship that has diagnostic utility? Is SLOS testing implicated when autism spectrum disorder (ASD) is the only clinical indication?
Aim: To determine if there is any correlation with a clinical indication of ASD and a biochemical diagnosis of SLOS, based on historical test request and assay data.
Methods: Six years (2008-2013) of clinical test requests for 7-dehydrocholesterol (7-DHC) level were classified and summarised according to indication and final test result.
Results: From the audit period, 988 valid test results from post-natal samples were identified. In plasma/serum, mean 7-DHC level was 264.7 μmol/L (normal range < 2.0) for confirmed SLOS cases. No tests performed due to an isolated clinical indication of ASD or where no clinical information was supplied were associated with 7-DHC levels diagnostic for SLOS.
Conclusions: Historical test data analysis supports the recommendation that autism/ASD as a single clinical feature is not an appropriate indication for SLOS (7-DHC) biochemical testing.
Keywords: 7-dehydrocholesterol; Smith-Lemli-Opitz syndrome; autism spectrum disorder.
© 2021 Paediatrics and Child Health Division (The Royal Australasian College of Physicians).