We do not know yet the broad significance of the up-regulation of pro-survival pathways in HPRT-deficiency; but we suspect that the molecular and the cellular adaptations caused by the purine metabolic defects in LNS/HPRT-deficiency generate purine metabolites such as uric acid that could bring about the augmentation of pro-survival signaling pathways and lead to the observed survival advantage. This evidence concerns the gene HPRT1 and hyperinsulinemic hypoglycemia, familial, 4.