PAX6 and aniridia: Evidence for the presence of distant regulatory elements downstream of human PAX6 came from genetic analyses of patients with congenital aniridia, some of whom have chromosomal rearrangements whose breakpoints are far downstream of the PAX6 transcriptional unit [32-36], suggesting that the rearrangement has separated distal regulatory elements from the body of the PAX6 gene, leading to defective PAX6 expression.