POU1F1 is a pituitary-specific transcription factor essential for anterior pituitary development and function 1. It specifies the differentiation and survival of three key anterior pituitary cell types: lactotrophs, somatotrophs, and thyrotrophs 2. POU1F1 functions as a sequence-specific DNA-binding transcription factor that activates growth hormone, prolactin, and thyroid-stimulating hormone genes through binding to consensus sequences and recruitment of RNA polymerase II machinery 3. The gene encodes multiple protein isoforms through alternative splicing, with the alpha and beta isoforms exhibiting distinct transactivation capacities on target promoters 4. Mutations in POU1F1 cause combined pituitary hormone deficiency (CPHD), characterized by deficiencies in growth hormone, prolactin, and thyroid-stimulating hormone, with variable inheritance patterns 5. Pathogenic variants range from missense mutations to intronic variants disrupting pre-mRNA splicing, leading to anterior pituitary hypoplasia and growth failure 4. Notably, POU1F1 interacts genetically with other developmental transcription factors; heterozygous variants in POU1F1 combined with SIX3 mutations cause digenic hypopituitarism with pituitary dysmorphology 6. Additionally, POU1F1 mutations have been associated with precocious or early puberty in some CPHD patients, suggesting roles in gonadotroph regulation 7.