At the same time, the phenotype reported here is associated with a complete loss of normal pitx2 at early developmental stages while the human phenotype, Axenfeld-Rieger syndrome, is caused by PITX2 haploinsufficiency; it is still unclear whether permanent inactivation of one allele of pitx2 can lead to a zebrafish phenotype with relevance to human disease. Here, PITX2 is linked to Axenfeld-Rieger syndrome.