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POU3F4 gene
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Gene

POU3F4 gene

The POU3F4 gene provides instructions for a transcription factor that plays a vital role in the development of the inner ear, specifically the cochlea.

Normal Function

The POU3F4 gene provides instructions for making a protein that helps regulate the activity of other genes. Proteins that perform this role are called transcription factors. The POU3F4 gene is part of a larger family of transcription factor genes called POU domain genes. These genes play a role in determining cell types in the brain and spinal cord (the central nervous system) during early development.

The POU3F4 protein is involved in the development of cells within a snail-shaped structure called the cochlea in the inner ear. The cochlea converts sound waves into electrical nerve impulses, which are then transmitted to the brain. This process is critical for normal hearing.

Health Conditions Related to Genetic Changes

Nonsyndromic hearing loss

Genetic changes that cause disease are called pathogenic variants. Pathogenic variants involving the POU3F4 gene cause nonsyndromic hearing loss, which is a partial or total loss of hearing that is not associated with other signs and symptoms.

Pathogenic variants in the POU3F4 gene cause a form of nonsyndromic hearing loss called DFNX2. DFNX2 is the most common type of X-linked nonsyndromic hearing loss, accounting for about half of all cases. X-linked conditions are caused by variants in genes on the X chromosome.

The signs and symptoms of DFNX2 differ in boys and girls:

  • In boys: Hearing loss begins before the child learns to speak (prelingual), worsens over time, and usually involves abnormalities of both the inner ear and the middle ear (mixed hearing loss).
  • In girls: Affected individuals tend to be less severely affected, with hearing loss usually beginning after the child learns to speak (postlingual).

The pathogenic variants in the POU3F4 gene that cause DFNX2 typically delete part of the gene or lead to the substitution of one amino acid for another in the POU3F4 protein. These variants prevent cells from producing any POU3F4 protein or cause cells to produce an altered version of the protein. The lack of functional POU3F4 protein disrupts the development of structures in the ear, particularly the cochlea, leading to hearing loss.

Other Names for This Gene

  • BRAIN-4
  • Brn-4
  • BRN4
  • DFN3
  • DFNX2
  • OTF9

Frequently Asked Questions

Hearing aids are often the first line, but many boys benefit from cochlear implantation, especially when the inner ear malformation is severe. Early fitting of hearing aids and enrollment in speech‑language therapy improve language outcomes.
Newborn hearing screening followed by a diagnostic audiogram can reveal conductive or mixed hearing loss. If hearing loss is detected, a high‑resolution CT or MRI of the temporal bone is performed to look for inner ear malformations characteristic of DFNX2, and a targeted genetic test for POU3F4 variants is ordered.
Yes, female carriers can experience mild to moderate hearing loss that may appear in adolescence or adulthood. The severity varies widely because of X‑inactivation patterns; some women remain asymptomatic while others have significant deficits.
Counselors assess the 50 % transmission risk to sons and 50 % carrier risk to daughters. They discuss options such as carrier testing for at‑risk relatives, prenatal diagnosis via chorionic villus sampling or amniocentesis, and preimplantation genetic testing if families choose IVF. They also provide information on early intervention services and support resources.===
Source: MedlinePlus, National Library of Medicine

MedlinePlus brings together authoritative health information from the National Library of Medicine (NLM), the National Institutes of Health (NIH), and other government agencies and health-related organizations.

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