A novel Z-score-based method to analyze candidate genes for age-related hearing impairment.

Objective: Approximately half of the variance of Age-Related Hearing Impairment (ARHI) is attributable to environmental risk factors, and the other half to genetic factors. None of these genes has ever been identified, but the genes involved in monogenic nonsyndromic hearing impairment are good candidates. Here we define and validate a quantitative trait value for ARHI, correcting for age and gender, to allow the genetic study of ARHI as a quantitative trait.

Mutations in the WFS1 gene that cause low-frequency sensorineural hearing loss are small non-inactivating mutations.

Hereditary hearing impairment is an extremely heterogeneous trait, with more than 70 identified loci. Only two of these loci are associated with an auditory phenotype that predominantly affects the low frequencies (DFNA1 and DFNA6/14). In this study, we have completed mutation screening of the WFS1 gene in eight autosomal dominant families and twelve sporadic cases in which affected persons have low-frequency sensorineural hearing impairment (LFSNHI).

A Dutch family with progressive autosomal dominant non-syndromic sensorineural hearing impairment linked to DFNA13.

We present a Dutch family with autosomal dominantly inherited mid-frequency and high-frequency sensorineural hearing impairment. Genetic linkage analysis in this family indicated linkage to DFNA13 with logarithm of the odds ratio (LOD) scores > +4. The majority of the affected persons presented with hearing impairment from the age of 30 years onwards, although hearing impairment was noted at about 10 years of age in two affected persons.

A common founder for the 35delG GJB2 gene mutation in connexin 26 hearing impairment.

Fifty to eighty percent of autosomal recessive congenital severe to profound hearing impairment result from mutations in a single gene, GJB2, that encodes the protein connexin 26. One mutation of this gene, the 35delG allele, is particularly common in white populations. We report evidence that the high frequency of this allelic variant is the result of a founder effect rather than a mutational hot spot in GJB2, which was the prevailing hypothesis.

A second gene for otosclerosis, OTSC2, maps to chromosome 7q34-36.

Otosclerosis due to abnormal bone homeostasis of the otic capsule is a frequent cause of hearing loss in adults. Usually, the hearing loss is conductive, resulting from fixation of the stapedial footplate, which prevents normal ossicular vibration in response to sound. An additional type of sensorineural hearing loss may be caused by otosclerotic damage to the cochlea.