How is SLOS diagnosed?
SLOS is confirmed by measurement of cholesterol and 7-dehydrocholesterol (7-DHC) by gas-chromatography mass spectrometry of blood serum. The gene defect leads to low total cholesterol and elevated amounts of the cholesterol precursors 7-DHC and 8-DHC. A strong clue that SLOS may be present in a child with autistic spectrum disorder is the presence of the second and third toes fused in the shape of the letter “Y”. In some cases, the abnormality is so slight that it can only be detected by looking at the toes viewed from the bottom of the foot. However, some normal non-SLOS people may have this toe abnormality as well.
