This gene encodes a member of the iroquois homeobox gene family, which are involved in several embryonic developmental processes. Knockout mice lacking this gene show that it is required for retinal cone bipolar cell differentiation, and that it negatively regulates potassium channel gene expression in the heart to ensure coordinated cardiac repolarization. Alternatively spliced transcript variants encoding different isoforms have been found for this gene. [provided by RefSeq, Nov 2011].