The European Union Concerted Action Programme on Genetic Hearing Impairment is concerned with co-ordinating work in this field to advance progress across the European Union, and with promoting collaboration with countries, such as the USA, outside the EU. The aim is to bring together clinical geneticists and audiologists, as well as basic scientists and other clinicians with a general interest in this field, to standardise the audiological and terminological approaches and publish state of the art interdisciplinary studies. This volume reports on the first symposium, focusing primarily on an update of the results of gene localization and identification within the field and the development of more relevant audiometric and vestibulometric investigations. The two opening chapters offer background information on the potentials and application of gene therapy in hearing disorders, and the progress so far, and the value of radiological investigations in congenital hearing impairment. There then follows coverage of the first co-ordinated studies. The audiometric chapters cover the criteria for use in linkage studies, the detection of carriers of recessive impairment and a description of a new technique for vestibular assessment in such individuals. Also includes in the book are a review of gene localization and identification in non-syndromal autosomal recessive hearing impairment, papers on gene localization in dominant and recessive non-syndromal hearing impairment, and several studies highlighting the relevance of mitochondrial mutation in the production of genetic hearing impairment. The developments in certain syndromal conditions such as Stickler syndrome, Hemifacial microsomia and Usher syndrome are also discussed.