Inner Ear Anomalies Are Frequent but Nonobligatory Features of the Branchio-oto-renal Syndrome

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Abstract
THE BRANCHIO-OTO-RENAL (BOR) syndrome is defined as an autosomal dominant inherited disorder characterized by the following 3 essential clinical features: (1) hearing loss with structural defects of the external (including earpits), middle, and/or inner ear; (2) second branchial arch defects; and (3) renal anomalies, ranging from mild hypoplasia to aplasia, which can lead to varying degrees of renal failure. Accompanying features such as lacrimal duct stenosis or a high-arched palate can also be present in these patients.1-4 One gene underlying the BOR syndrome, EYA1 (chromosome 8q13.3), has been identified.5-8 Recent linkage analysis provided evidence for a second gene on chromosome 1q31.9 This disorder has a high penetrance but variable clinical expression. The major clinical findings associated with BOR syndrome are branchial clefts, hearing loss, and renal failure.1-4,10,11 The general prevalence of BOR syndrome is 1 in 40 000 people, and it occurs in 2% of profoundly deaf children.12