PHOX2B is a transcription factor essential for autonomic nervous system development, particularly in noradrenergic neuron populations including the locus coeruleus 1. It functions as a DNA-binding transcriptional activator that determines neurotransmitter phenotype by enhancing promoters of genes like dopamine beta-hydrolase and regulating cAMP-response elements [UniProt]. PHOX2B is critical for development of the retrotrapezoid nucleus (RTN), a medullary cluster of glutamatergic neurons that mediates central respiratory chemoreception and CO2 detection 2. It also controls enteric nervous system development and brainstem circuits governing feeding behaviors 34. Clinically, PHOX2B mutations cause congenital central hypoventilation syndrome (CCHS), characterized by deficient autonomic control of ventilation and global dysautonomia 5. Mutations impair RTN development, consequently disrupting the central respiratory chemoreflex 2. PHOX2B also serves as a diagnostic marker in Hirschsprung disease and is a predisposition gene for neuroblastoma, where it acts as a master transcriptional regulator defining the noradrenergic identity module essential for tumor development 67. PHOX2B immunohistochemistry provides highly sensitive and specific diagnostic utility in neuroblastoma 7. Recent immunotherapeutic approaches targeting PHOX2B-derived peptides show promise for neuroblastoma treatment 8.