No evidence found for SLOS testing in isolated autism spectrum disorder cases

There is no diagnostic utility in conducting Smith-Lemli-Opitz syndrome (SLOS) testing for individuals with only an autism spectrum disorder (ASD) as their clinical indication, according a recent study analyzing several years of clinical data. The findings suggest that while there is a high incidence of ASD features in individuals with SLOS, the converse relationship does not hold true.

Researchers examined 6 years’ worth of clinical test requests for 7-dehydrocholesterol (7-DHC) level, a biomarker associated with SLOS, and classified and summarized them according to indication and final test results.

Out of the 988 valid test results from post-natal samples analyzed during the audit period (2008-2013), it was found that the mean 7-DHC level in plasma/serum for confirmed SLOS cases was 264.7 μmol/L (normal range < 2.0). However, no tests performed solely based on a clinical indication of ASD or in cases where no clinical information was provided showed 7-DHC levels indicative of SLOS.

Based on the analysis of historical test data, the study’s conclusions support the recommendation that SLOS (7-DHC) biochemical testing should not be conducted when autism/ASD is the sole clinical feature presented.

These findings suggest that ASD alone is not an appropriate indication for SLOS testing, highlighting the need for careful consideration of clinical symptoms and indications before ordering specific genetic or biochemical tests.

Reference
Kaub PA, Sharp PC, Ranieri E, et al. Isolated autism is not an indication for Smith-Lemli-Opitz syndrome biochemical testing. J Paediatr Child Health. 2022;58(4):630-635. doi: 10.1111/jpc.15795. Epub 2021 Nov 12. PMID: 34773316.