HPRT1 and neuroblastoma: The extent to which these defects clarify mechanisms of pathogenesis in LND patients is still to be established, but these results demonstrate clearly in fully differentiated normal and LND human fibroblasts and in dopaminergic SH-SY5Y neuroblastoma cells that HPRT plays strong developmental roles in many functions and processes vital for programs key to CNS development, a valuable insight into HPRT neuronal regulatory function whether or not it fully explains the disease phenotype.