[a DNA-binding nuclear transcription factor. HOX11 is an orphan homeobox gene since it is located at a site outside the 4 mammalian HOX clusters. Whereas the orthodox HOX genes encode a combinatorial system of positional specification along the anterior-posterior axis of the embryo, the function of orphan homeobox genes is less well understood. Essential for the survival of splenic precursors during organogenesis. (from OMIM) ( NCI )]