Hearing impairment is a very common sensory deficit in the human population, and genetics plays an important role in its aetiology. It is estimated that mutations in the same gene. As more and more different mouse mutants are studied, it is becoming clear that many of them shows quite distinctive abnormalities. This emphasises the fact that it is only reasonable to describe a mouse mutant as a model for human deafness when we know at least that the same gene is involved in causing the pathology. In general,