Marsha E. Sheffield, Richard J. Late-onset non-syndromic hearing impairment is the most common type of neurological dysfunction in the elderly. It can be either acquired or inherited, although the relative impact of heredity on this type of loss is not known.
To date, nine different genes have been localized, but none has been cloned. Using an extended American family in which a gene for autosomal dominant late-onset non-syndromic hearing impairment is segregating, we have identified a new locus, DFNA10 , on chromosome 6. In addition, by medical history, it is described as congenital or late-onset, and inherited or acquired. Inherited losses aie subclassified as syndromic or non-syndromic to reflect the presence or absence of co-inherited physical abnormalities 2.
In the United States, one in neonates has congenital severe-to-profound hearing impairment of sufficient magnitude to preclude normal speech development 3 ; in half of these affected babies, the loss is inherited. The prevalence of hearing impairment increases with age, and by puberty, the number of affected persons doubles 4. This age-related decrease in auditory acuity makes late-onset hearing impairment the most common type of neurological dysfunction of the elderly.
Both environmental and hereditary factors impact on age-related hearing impairment, however the relative contribution of each is not known. Most types of inherited late-onset non-syndromic hearing impairment appear to be autosomal dominant. To date, nine different genes have been localized although none has been cloned Table 1. Using an extended American family in which a gene for autosomal dominant late-onset progressive non-syndromic hearing impairment is segregating, we have identified a new locus, DFNA10 , on chromosome 6q.
Two-point lod scores of 4. Linkage analysis was performed on a large multi-generational family from the United States Fig. Affected persons exhibited an inexorably progressive sensorineural hearing loss beginning in the second-to-fifth decades and leading ultimately to severe-to-profound hearing impairment requiring the use of amplification Fig.
