PHOX2B (EP312)

Paired-like homeobox 2B (PHOX2B) is a transcription factor located on chromosome 4p135 which is crucial to the formation of autonomic ganglia in the autonomic nervous system (ANS). PHOX2B gene is strictly expressed in neural crest derivatives committed to the noradrenergic phenotype.2 The PHOX2B gene encodes a paired-like homeo-domain transcription factor with an extra-axial expression pattern restricted to the ANS.1,3-4 Neuroblasts of peripheral neuroblastic tumors are derived from the sympathoadrenal lineage, a division of the ANS. PHOX2B has been observed in peripheral neuroblastic tumors, neuroblastomas, paragangliomas, ganglioneuroblastomas, ganglioneuromas and pheochromocytomas.3,5 PHOX2B has been reported to be negative in other small round blue cell tumors.3