PAX6 and aniridia: The best-studied example of the cis-regulatory ‘switch off’ phenomenon has been associated with aniridia (MIM 106210), a panocular developmental eye disorder in which most cases are due to het-LOF mutations in PAX6. A proportion of cases that are clinically indistinguishable from those with nonsense mutations result from deletions or translocation BPs located 3′ to the gene (32).