GBX1 (gastrulation brain homeobox 1) is a DNA-binding transcription factor that functions as a homeodomain protein targeting TAATTA motifs in double-stranded DNA 1. The gene encodes a homeobox protein active in RNA polymerase II-mediated transcriptional regulation [GO annotations]. GBX1 is dynamically expressed during embryonic development, first appearing during gastrulation and subsequently in the central nervous system including rhombomeres 3 and 5, optic vesicles, and the medial ganglionic eminence 2. The protein exhibits preferential expression in germinal vesicle oocytes 3 and participates in epithelial differentiation and transdifferentiation processes, functioning cooperatively with transglutaminase 2 and TGF-beta in retinoic acid-induced epidermal-to-mucosal transdifferentiation 4. Clinically, GBX1 variants have been associated with neurological dysfunction. A de novo GBX1 variant (c.910C>T, p.Gln304*) was identified in a patient with focal epilepsy and developmental delay, representing the first reported human disease association 5. Zebrafish models with gbx1 disruption demonstrated interocular morphological abnormalities and increased susceptibility to epileptiform activity, confirming GBX1's importance in neurological function 5.