IKZF2 (IKAROS family zinc finger 2), also known as HELIOS, is a member of the Ikaros family of zinc finger transcription factors . It is predominantly expressed in hematopoietic cells, particularly regulatory T cells (Tregs) and natural killer (NK) cells, where it plays critical roles in lymphocyte development and immune regulation . IKZF2 contains an N-terminal DNA-binding domain with four zinc fingers and a C-terminal protein-binding domain mediating dimerization . Mechanistically, HELIOS maintains Treg stability and function by suppressing IL2 transcription . Germline dominant negative variants affecting the DNA-binding zinc fingers cause ICHAD syndrome (Immunodysregulation, Craniofacial anomalies, Hearing impairment, Athelia, Developmental delay), while loss-of-function variants primarily result in immunodeficiency and immune dysregulation without syndromic features . IKZF2 is also essential for outer hair cell maturation in the cochlea, with mutations leading to sensorineural hearing loss . Thus, IKZF2 serves as a critical regulator of both immune homeostasis and neurodevelopment.