Accumulation of sterol intermediates in Dhcr7−/−and Dhcr24-deficient neurons. Comparison of cholesterol (A), desmosterol (B), and 7-DHC (C) levels between WT, Dhcr7−/−, and Dhcr24-deficient neurons (Dhcr24−/−). Neurons were cultured in defined cholesterol-free medium for 3 days and subjected to LC-MS/MS. Values correspond to mean ± SEM of 8–12 replicates. In all panels, statistical significance between individual groups is denoted by asterisks (****p < 0.0001); #### denotes the difference between WT and Dhcr24-deficient neurons (p < 0.0001).