FISH studies in a girl with sporadic aniridia and an apparently balanced de novo t(11;13)(p13;q33) translocation detect a microdeletion involving theWAGR region

Conventional cytogenetic studies on a female infant with sporadic aniridia revealed what appeared to be a balanced de novo t(11;13) (p13;q33) transloc ation. Fluorescence in situ hybridization (FISH) investigations, however, d etected the presence of a cryptic 11p13p14 deletion which included the WAGR region and involved approximately 7.5 Mb of DNA, including the PAX6 and WT 1 genes. These results account for the patient's aniridia, and place her at high risk for developing Wilms' tumour. The absence of mental retardation in the patient suggests that the position of the distal breakpoint may also help to refine the mental retardation locus in the WAGR contiguous gene sy ndrome (Wilms', aniridia, genital anomalies and mental retardation).