MPDZ and retinitis pigmentosa 1: The chromosomal gene MPDZ (multiple PDZ domain crumbs cell polarity complex component, OMIM: 603785) is another gene previously deemed to be responsible for pathology in rdd chicks, and heterozygous variations in MPDZ were identified in human retinitis pigmentosa (RP) and Leber congenital amaurosis (LCA) [8].