There are exceptions, for example, for children born with aniridia, an array‐CGH is commonly used to detect a deletion involving the WT1 and PAX6 genes, if negative then Wilms tumor, aniridia, genitourinary anomalies, and mental retardation (WAGR) syndrome, can be ruled out and single gene PCR‐based sequencing of PAX6 is undertaken to identify pathogenic variants causing isolated aniridia. The gene discussed is PAX6; the disease is isolated aniridia.