Detection of submicroscopic chromosomal deletions in aniridia patients using fluorescence in-situ hybridization and a panel of cosmids covering the wt1 gene.

A series of cosmids have been isolated from a human chromosome 11-specific cosmid library using the human Wilms tumour predisposition gene cDNA, WT33. Seven overlapping cosmids were isolated which cover the genomic sequence of WT1 and in situ hybridisation shows that they all localise to the p13 region of chromosome 11. Chromosomes from patients with aniridia and Wilms tumour, and a small subband deletion in 11p13, were analysed and no hybridisation signal was seen on the deletion chromosomes. These cosmids, therefore, can be used to analyse chromosomes from patients with sporadic aniridia for submicroscopic deletions. Aniridia patients who show normal hybridisation patterns on both chromosomes need no longer be screened for Wilms tumours.