Given the known global metabolic alterations observed in patients with Bardet-Biedl syndrome, we ruled out that the accumulation of cholesterol in mutant OSs is due to hypercholesterolemia by analysing the total serum cholesterol, which showed no significant increase in bbs1 mutants compared to sibling controls (Supplementary Fig. 14). This evidence concerns the gene BBS1 and Bardet-Biedl syndrome.