DHCR7 and Smith-Lemli-Opitz syndrome: We have shown that in the disorder, Smith-Lemli-Opitz syndrome (SLOS) where 7-DHC is abundant, on account of a defect in 7-dehdrocholesterol reductase (DHCR7), 26-hydroxy-7-oxocholesterol (26H,7O-C) and 25-hydroxy-7-oxocholesterol (25H,7O-C) are evident in plasma, as are their 7β-reduced forms, presumably formed by HSD11B1 from the 7-oxo precursors [[78], [79], [80], [81]].