MAML3 (Mastermind Like Transcriptional Coactivator 3) functions as a transcriptional coactivator in the Notch signaling pathway, amplifying NOTCH-induced transcription of target genes like HES1. While the provided abstracts do not detail MAML3's primary molecular mechanism, its clinical significance emerges primarily through fusion events rather than standard gene function. MAML3 fusion genes represent a distinct oncogenic driver in pheochromocytomas and paragangliomas (PPGLs). MAML3 fusions occur in approximately 3.65% of PCC/PGL cases and define a molecularly distinct subtype characterized by Wnt pathway dysregulation 1. MAML3-fusion tumors show increased expression of neuroendocrine-to-mesenchymal transition markers, MYC-targets, and angiogenesis-related genes, creating a unique tumor microenvironment with enhanced vascular networks 2. Critically, MAML3-fusion status strongly correlates with metastatic risk, making it a prognostic marker for disease progression 12. Beyond PPGLs, MAML3 participates in oncogenic fusions in undifferentiated round cell sarcomas, including BCOR-MAML3 and related chimeric fusion proteins 345. MAML3-fusion sarcomas present in young adults with variable anatomic distribution and often display spindle cell morphology distinct from other fusion-positive tumors. Therapeutically, MAML3-fusion PPGL tumors demonstrate PD-L1 and CD40 overexpression, suggesting immunotherapy vulnerability 26.