Nonsyndromic Deafness, Autosomal Recessive

What is nonsyndromic deafness, autosomal recessive?

Nonsyndromic deafness is hearing loss that is not associated with other signs and symptoms. In contrast, syndromic deafness involves hearing loss that occurs with abnormalities in other parts of the body.

Nonsyndromic deafness is often genetic and can be described by its pattern of inheritance. An autosomal recessive inheritance pattern means that two copies of an altered gene are present in each cell. Autosomal recessive deafness is designated DFNB. Each type is numbered in the order in which it was described. For example, DFNB1, DFNB2, and DFNB3 are particular forms of autosomal recessive deafness.

Nonsyndromic deafness, autosomal recessive is a subtype of nonsyndromic deafness.

Most forms of autosomal recessive deafness are characterised by hearing loss from birth. The level of hearing loss varies within and among families.

Autosomal recessive deafness is typically caused by changes to structures in the inner ear. The inner ear consists of three parts: a snail-shaped structure called the cochlea that helps process sound, nerves that send information from the cochlea to the brain, and structures involved with balance. Hearing loss caused by changes in the inner ear is called sensorineural deafness.

How common is nonsyndromic deafness, autosomal recessive?

Between 75 percent and 80 percent of all nonsyndromic deafness is inherited in an autosomal recessive pattern. In many populations, mutations in the GJB2 gene cause most cases of nonsyndromic deafness. Certain mutations in this gene are most common in particular ethnic groups, such as people of Ashkenazi (eastern or central European) Jewish, Asian, or Caucasian (white) ancestry.

What genes are related to nonsyndromic deafness, autosomal recessive?

Mutations in the CDH23, CLDN14, ESPN, GJB2, GJB6, MYO15A, MYO6, MYO7A, OTOF, PCDH15, SLC26A4, STRC, TECTA, TMC1, TMIE, TMPRSS3, and USH1C genes cause nonsyndromic deafness, autosomal recessive.

The GJB3 gene is associated with nonsyndromic deafness, autosomal recessive.

Mutations in the GJB2 gene cause more than half of all autosomal recessive deafness in many populations. This gene provides instructions for making a protein called connexin 26. The GJB6 gene also provides instructions for making a connexin protein, connexin 30. These proteins form parts (subunits) of channels called gap junctions, which allow communication between neighboring cells. Mutations in connexin proteins that make up gap junctions may affect the function or survival of cells that are needed for hearing.

Other genes related to nonsyndromic deafness affect the structure or function of components of the inner ear. The function of several of these genes (such as TMC1 and STRC) is not known. Different mutations in the same gene can cause different types of hearing loss, and some genes are associated with both nonsyndromic and syndromic forms of deafness.

In some families, deafness is believed to be caused by an altered gene, but the gene has not been identified.

How do people inherit nonsyndromic deafness, autosomal recessive?

A person with this form of nonsyndromic deafness has two altered copies of a gene in each cell, one copy inherited from each parent. Usually, the parents of an individual with autosomal recessive deafness are both carriers of one copy of the altered gene. These carriers do not have hearing loss.

What other names do people use for nonsyndromic deafness, autosomal recessive?

  • ARNSHL
  • Autosomal recessive nonsyndromic hearing loss

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