PAX6 and isolated aniridia: In contrast to the downstream region of PAX6, which has a significant role in disease aetiology of aniridia patients, the upstream region towards RCN1 is less well studied; it includes the only E-200 element and E-55 cluster, implicating this region as a regulatory ‘desert’ even though it is known to contain a number of evolutionarily conserved sites (23,24).