LIM homeobox 1 is a protein that in humans is encoded by the LHX1 gene.[5] This gene encodes a member of a large protein family which contains the LIM domain, a unique cysteine-rich zinc-binding domain. The encoded protein is a transcription factor important for control of differentiation and development of neural and lymphoid cells. It is also key in development of renal and urogenital systems and is required for normal organogenesis.[6] A similar protein in mice is an essential regulator of the vertebrate head organizer.[5]