Paired box gene 6 (PAX6) is the causative gene of aniridia. it is a dominantly inherited eye abnormality characterized by partial or complete absence of the iris. The PAX6 gene is located on chromosome 11 p13 and contains 14 exons. It is expressed mainly in the developing eye and central nervous system. Submicroscopic copy number variations are common in the human genome. Submicroscopic deletions may cause several human diseases, either by disrupting coding sequences or by eliminating regulatory elements essential for expression of the gene in question. Over the past several years, array-based comparative genomic hybridization has become an increasingly useful too] for both identifying normal cytogenetic variations and characterizing chromosomal abnormalities associated with developmental delays and cancer. Our results support the notion that assessing copy number variation of the PAX6 gene itself and also of flanking regions, may contribute to the molecular diagnosis of aniridia. (C) 2009 Elsevier Ltd. All rights reserved.