A novel locus for autosomal dominant nonsyndromic hearing loss, DFNA50, maps to chromosome 7q32 between the DFNB17 and DFNB13 deafness loci

Progressive hearing loss is a significant problem in all ageing populations. By the age of 80 years, nearly 50% of individuals have hearing loss that impairs their ability to communicate easily, leading to increasing social isolation.1 Progressive hearing loss in middle and late adulthood is considered multifactorial, with involvement of both genetic and environmental factors.2 In contrast, childhood or adolescent hearing loss is often inherited as an autosomal dominant Mendelian trait, representing about 20% of all cases of hereditary nonsyndromic sensorineural hearing impairment (NSSHI). Postlingual inherited deafness is usually moderate to severe and progressive, and it often affects a particular range of frequencies.3 Hereditary deafness has proved extremely heterogeneous genetically; more than 40 loci have been mapped for autosomal dominant (AD) NSSHI, and 17 deafness genes from these loci have been identified to date.4 Linkage analysis using large pedigrees is a useful tool for mapping and identifying novel deafness genes, a key step for improving our current understanding of auditory function. Here we describe the localisation of a novel DFNA locus on chromosome 7q32, involving the study of a Spanish family with postlingual and progressive hearing loss affecting all frequencies. ### Family data A five generation family (S403) with a history of ADNSSHI was identified through the Hospital Universitario de Valladolid, Spain. The pedigree consisted of 74 members, 37 of whom were affected (fig 1). Appropriate informed consent was obtained from all participants of the study and from parents of subjects younger than 18 years. Clinical evaluation was carried out, blood samples were collected from 55 family members, and DNA was extracted by standard techniques. Environmental factors were excluded as causes of hearing impairment. No syndromic features were present. Tympanometry with acoustic reflex testing indicated proper functioning of the middle ear, and pure tone audiometry was performed to test …