Polymerase Chain Reaction–Based Risk Assessment for Wilms Tumor in Sporadic Aniridia

Abstract

Purpose: Sporadic cases of aniridia have a 30% risk for the development of Wilms tumor. Current guidelines for sporadic aniridia recommend screening by renal ultrasonography for the presence of tumors every 6 months until age 5 years. Deletions of chromosome 11p13 that affect both PAX6 (aniridia) and WT1 (Wilms tumor) loci are the basis for the association of these two uncommon disorders. We sought to develop a rapid polymerase chain reaction–based test that could rule out a chromosome 11p13 deletion covering the PAX6-WT1 region in sporadic aniridia. Methods: Five patients with sporadic aniridia were recruited. Polymerase chain reaction–based genotyping was carried out for six highly informative marker loci across the PAX6-WT1 region to determine whether these patients had one or two haplotypes. The results were compared with those obtained from two cell lines with known deletions in the PAX6-WT1 region. Results: All five patients were heterozygous at least at one of the four marker loci in the PAX6-WT1 region, indicating that there were no cases of gross chromosomal deletion. The cell lines showed hemizygosity in the four marker loci within the PAX6-WT1 region and in one of the two flanking marker loci. Conclusions: We have developed a rapid DNA test with an estimated sensitivity of 94.0% to 99.2%, using standard DNA diagnostic techniques and equipment, to rule out chromosomal deletion in sporadic aniridia. Patients in whom a chromosome 11p13 deletion has been ruled out do not require repeated renal imaging to screen for Wilms tumor.