{"type":"root","children":[{"type":"paragraph","children":[{"type":"text","value":"Paired-like homeobox 2b (PHOX2B), also known as neuroblastoma Phox (NBPhox), is a protein that in humans is encoded by the PHOX2B gene located on chromosome 4. It is expressed exclusively in the nervous system, in most neurons that control the viscera (cardiovascular, digestive and respiratory systems). It is also required for neuron differentiation. Mutations in human PHOX2B cause a rare disease of the autonomic nervous system (dysautonomia): congenital central hypoventilation syndrome (associated with respiratory arrests during sleep and, occasionally, wakefulness), Hirschsprung"},{"type":"text","value":"'"},{"type":"text","value":"s disease (partial agenesis of the enteric nervous system), ROHHAD, and tumors of the sympathetic ganglia."}]},{"type":"paragraph","children":[{"type":"text","value":"PHOX2 gene over-expression in Neuroblastoma (NB) tumors and cell lines suggests these genes may be widely involved in Neuroblastoma development through either a direct mechanism of up-regulation or a failure in maintaining proper transcript levels after embryonic development. The PHOX2B expression has been observed in all peripheral neuroblastic tumors, paragangliomas, and pheochromocytomas tested but in no other pediatric tumors among the 388 cases studied by expression microarray and the 109 cases studied by immunohistochemical analysis. PHOX2B and CD57 have been found to be useful markers of Neuroblastoma. PHOX2B is specific for Neuroblastoma in its differential diagnosis with other small round cell tumors, and its nuclear staining may be helpful for accurate bone marrow tumor quantification."}]}]}