What are the other Names for this Condition? (Also known as/Synonyms)

• Deafness, X-Linked, DFN
• X-Linked Isolated Sensorineural Deafness Type DFN
• X-Linked Non-Syndromic Neurosensory Hearing Loss Type DFN

What is X-Linked Isolated Neurosensory Deafness Type DFN? (Definition/Background Information)

• X-Linked Isolated Neurosensory Deafness Type DFN is a hearing disorder inherited in a sex-linked manner. Only 1% of heritable deafness cases are inherited as an X-linked trait (DFN type)
• The majority of cases presenting at birth concern perceptive deafness (with a neurosensory origin associated with the inner ear) rather than conductive deafness (anomalies in the amplification of sound waves between the middle ear - tympanum and auditory ossicles - and the outer ear)

(Source: X-Linked, Non-Syndromic Sensorineural Deafness Type DFN; Orphanet, National Institute of Health and Medical Research (INSERM), Paris.)

Who gets X-Linked Isolated Neurosensory Deafness Type DFN? (Age and Sex Distribution)

• X-Linked Isolated Neurosensory Deafness Type DFN is a rare congenital disorder, constituting about 1% of all inherited cases of deafness. The presentation of symptoms may occur at birth
• The disorder predominantly affects males
• Worldwide, individuals of all racial and ethnic groups may be affected

What are the Risk Factors for X-Linked Isolated Neurosensory Deafness Type DFN? (Predisposing Factors)

• A positive family history may be an important risk factor, since X-Linked Isolated Neurosensory Deafness Type DFN can be inherited
• Belonging to the male gender is a risk factor for the disorder

It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases one’s chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others.

Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your healthcare provider.

What are the Causes of X-Linked Isolated Neurosensory Deafness Type DFN? (Etiology)

• X-Linked Isolated Neurosensory Deafness Type DFN is predominantly caused by mutation(s) in the POU3F4 gene
• Mutation(s) in 3 other genes may also cause X-Linked Isolated Neurosensory Deafness Type DFN. The disorder is inherited in an X-linked recessive pattern

The gene associated with this condition is located on the X chromosome, which is one of the two sex chromosomes. In males (who have only one X chromosome), one altered copy of the gene in each cell is sufficient to cause the condition. In females (who have two X chromosomes), a mutation would have to occur in both copies of the gene to cause the disorder. Because it is unlikely that females will have two altered copies of this gene, males are affected by X-linked recessive disorders much more frequently than females. A characteristic of X-linked inheritance is that fathers cannot pass X-linked traits to their sons.

What are the Signs and Symptoms of X-Linked Isolated Neurosensory Deafness Type DFN?

The signs and symptoms of X-Linked Isolated Neurosensory Deafness Type DFN may include:

• Mild, moderate or severe hearing loss
• The severity may vary from one individual to another

How is X-Linked Isolated Neurosensory Deafness Type DFN Diagnosed?

X-Linked Isolated Neurosensory Deafness Type DFN is diagnosed on the basis of the following information:

• Complete physical examination
• Thorough medical history evaluation
• Assessment of signs and symptoms
• Hearing tests
• Laboratory tests
• Imaging studies
• Biopsy studies, if necessary

Many clinical conditions may have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis.

What are the possible Complications of X-Linked Isolated Neurosensory Deafness Type DFN?

The complications of X-Linked Isolated Neurosensory Deafness Type DFN may include:

• Permanent loss of hearing
• Isolation from society and depression

Complications may occur with or without treatment, and in some cases, due to treatment also.

How is X-Linked Isolated Neurosensory Deafness Type DFN Treated?

There is no cure for X-Linked Isolated Neurosensory Deafness Type DFN, since it is a genetic condition. The treatment is usually given to manage the signs and symptoms and any complication that may develop.

How can X-Linked Isolated Neurosensory Deafness Type DFN be Prevented?

X-Linked Isolated Neurosensory Deafness Type DFN may not be preventable, since it is a genetic disorder.

• Genetic testing of the expecting parents (and related family members) and prenatal diagnosis (molecular testing of the fetus during pregnancy) may help in understanding the risks better during pregnancy
• If there is a family history of the condition, then genetic counseling will help assess risks, before planning for a child
• Active research is currently being performed to explore the possibilities for treatment and prevention of inherited and acquired genetic disorders

Regular medical screening at periodic intervals with tests and physical examinations are recommended.

What is the Prognosis of X-Linked Isolated Neurosensory Deafness Type DFN? (Outcomes/Resolutions)

• The prognosis of X-Linked Isolated Neurosensory Deafness Type DFN is dependent upon the severity of the signs and symptoms and associated complications, if any
• Individuals with mild conditions have better prognosis than those with severe symptoms and complications
• Typically, the prognosis may be assessed on a case-by-case basis

Additional and Relevant Useful Information for X-Linked Isolated Neurosensory Deafness Type DFN:

X-Linked Isolated Neurosensory Deafness Type DFN is also known by the following names: 

• X-Linked Isolated Neurosensory Hearing Loss Type DFN
• X-Linked Isolated Sensorineural Hearing Loss Type DFN
• X-Linked Non-Syndromic Neurosensory Deafness Type DFN
• X-Linked Non-Syndromic Sensorineural Hearing Loss Type DFN

The following DoveMed website link is a useful resource for additional information:

http://www.dovemed.com/diseases-conditions/rare-disorders/