Genetic syndromes involving hearing

Objective: The fundamental processes involved in the mechanism of hearing seem to be controlled by hundreds of genes and hereditary hearing impairment may be caused by a large variety of genetic mutations in different genes. Approximately 150 loci for monogenic disorders (for which hearing loss is the only manifestation and therefore is nonsyndromic) and for syndromic disorders, have been mapped to the human genome. The identification of these genes and unctional analysis of the proteins they encode, are paving the way towards a better understanding of the physiology and pathophysiology of the auditory system. To date,approximately50 causative genes have been identified. Methods: The clinicaland neuroradioldical findings of syndromal hearing impairment areanalysed. Results: This paper presents an updated report on genetic syndromes in which a hearing impairment is involved, with a particular attention to the ones associated with external ear and craniofacial malformations. Conclusions: Concepts in human genetics are rapidly evolving together with technologies. The concept itself of gene is changing. A genetic diagnosis of syndromal hearing impairment has many practical consequences: it can implies specific prognosis,specific management, specific recurrence risk in relatives and,if the diagnosis is confirmed at the molecular level,possibility of a specific early prenatal diagnosis for severe syndromes.It is important to highlight the necessity that the pediatric otolaryngologist must have a close collaboration with a clinical geneticist and a neuroradiologist.