AHI1, encoding the Jouberin protein, is an alternatively spliced signaling molecule that contains seven Trp-Asp (WD) repeats, an SH3 domain, and numerous SH3-binding sites. The gene is expressed strongly in embryonic hindbrain and forebrain, and AHI1 may be required for both cerebellar and cortical development in humans. Defects in AHI1 are the cause of Joubert syndrome 3, an autosomal recessive brain congenital malformation. The exact function of the AHI1 gene is not yet known.