Conversely, examination of the fetal and non-fetal skin and lung-derived fibroblasts obtained from cystinosis patients revealed normal [GSH]/[GSSG] ratio under steady-state conditions and following inhibition of trans-sulfuration pathway and CySS/Glu antiporter system xc− [52], suggesting that the loss of cystinosin function does not lead to cytosolic redox perturbations, at least in cystinotic cells in culture. The gene discussed is CTNS; the disease is cystinosis.