PHOX2A is a paired-like homeodomain transcription factor essential for autonomic nervous system development and noradrenergic neuron specification 1. It functions as a DNA-binding transcription activator that regulates catecholamine biosynthetic genes, including tyrosine hydroxylase and dopamine-beta-hydroxylase, maintaining noradrenergic phenotype 2. PHOX2A also regulates the alpha3 nicotinic acetylcholine receptor gene, a "pan-autonomic" gene expressed in all ganglionic cells, potentially through protein-protein interactions with Sp1 2. Expression of PHOX2A is regulated downstream by PHOX2B, which directly binds to PHOX2A's 5' regulatory region to transactivate its promoter 13. Functionally, PHOX2A knockouts in zebrafish recapitulate ocular congenital cranial dysinnervation disorder (oCCDD) phenotypes, demonstrating its critical role in cranial motor neuron development 45. Disease-relevant variants like p.(Trp137Cys) show reduced DNA-binding capability via protein binding microarray analysis 45. Additionally, PHOX2A is significantly overexpressed in neuroblastoma tumors and cell lines, suggesting involvement in neuroendocrine malignancy 6. Mutations in PHOX2A are associated with congenital fibrosis of extraocular muscles and other cranial motor disorders 7.