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.