GON4L (gon-4 like) is a nuclear transcription regulator with dual roles in histone gene expression and transcriptional repression. As a primary function, GON4L acts as a key transcriptional activator of histone genes. It cooperates with CRAMP1 to selectively promote linker histone H1 gene expression by occupying H1 promoters at the histone locus body and replication-independent loci 12. GON4L mechanistically functions through protein-protein interactions: it associates with CRAMP1 via its PAH domains to activate H1 transcription 1, and forms a repressor complex with YY1, SIN3A, and HDAC1 to mediate transcriptional repression 3. In cancer contexts, GON4L promotes tumor growth by facilitating YY1 interaction with androgen receptor to drive CD24 expression across multiple cancer types 4. Disease relevance includes Li-Takada-Miyake syndrome, where biallelic GON4L loss-of-function variants cause microcephaly, craniofacial abnormalities, and situs inversus, indicating essential roles in neurodevelopment and left-right patterning 5. GON4L is also implicated in lung cancer predisposition 6 and melanoma through NTRK1 fusion events 7. Clinically, GON4L expression levels may serve as biomarkers for cancer prognosis and represent therapeutic targets in malignancies.