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Branchio-oto-renal syndrome (BOR) (MIM 113650) is an autosomal dominant condition that has an incidence of approximately 1/40,000 and accounts for about 2% of profoundly deaf children. BOR is caused by mutations in the EYA1 gene and can manifest with hearing loss, preauricular pits ('ear pits'), pinna abnormalities, branchial fistulae (lateral fistula of the neck) and cysts, and renal anomalies. Prospective patients should have at least three of the four following major features: deafness, branchial defects, ear pits and renal anomalies. The EYA1 gene is a human homologue of the Drosophila eyes absent gene and the two genes share a highly conserved C-terminal region known as the eyaHR (EYA1 homologous region). EYA1 consists of 16 coding exons, with exons 8-16 coding for the eyaHR. Molecular genetic testing initially consists of mutation screening of exons 8-16, using denaturing high performance liquid chromatography (DHPLC) and sequencing of any shifts. This is followed by quantitative fluorescent PCR to identify any large deletions within the gene, and finally DHPLC screening of exons 1-7, if appropriate. Since screening started in November 2001, over 40 patients have been tested, the outcome of which will be presented, including clinical and mutation information. [ABSTRACT FROM AUTHOR]