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

• Connexin 26 Deafness 
• Deafness Nonsyndromic,Connexin 26 Linked
• GJB2-Related Deafness

What is Non-Syndromic Hearing Loss and Deafness? (Definition/Background Information)

• Non-Syndromic Hearing Loss and Deafness (DFNB1) is an inherited deafness, caused by mutation(s) in GJB2 and GJB6 genes
• The disorder is inherited in an autosomal recessive manner

Who gets Non-Syndromic Hearing Loss and Deafness? (Age and Sex Distribution)

• Non-Syndromic Hearing Loss and Deafness is a rare congenital disorder. The presentation of symptoms may begin in infancy 
• Both males and females may be affected
• Worldwide, individuals of all racial and ethnic groups may be affected

What are the Risk Factors for Non-Syndromic Hearing Loss and Deafness? (Predisposing Factors)

• A positive family history may be an important risk factor, since Non-Syndromic Hearing Loss and Deafness can be inherited
• Currently, no other risk factors have been clearly identified for DFNB1

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 Non-Syndromic Hearing Loss and Deafness? (Etiology)

• Non-Syndromic Hearing Loss and Deafness is caused by mutation(s) in GJB2 or GJB6 genes, which code for connexin 26 and connexin 30 proteins, respectively
• GJB2 and GJB6 gene mutations are inherited in an autosomal recessive manner

Autosomal recessive: Autosomal recessive conditions are traits or disorders that occur when two copies of an abnormal gene have been inherited on a non-sex chromosome. If both parents have an autosomal recessive condition, there is a 100% likelihood of passing on the mutated genes to their children. If, however, only one mutant copy of the gene is inherited, the individual will be a carrier of the condition, but will not be present with any symptoms. Children born to two carriers, have a 25% chance of being homozygous dominant (unaffected), a 50% chance of being heterozygous (carrier), and a 25% chance of being homozygous recessive (affected).

What are the Signs and Symptoms of Non-Syndromic Hearing Loss and Deafness?

The signs and symptoms of Non-Syndromic Hearing Loss and Deafness may include:

• Vestibular dysfunction (present in 5-29% of the cases)
• Sensorineural hearing loss

(Source: DFNB1; Genetic and Rare Diseases Information Center (GARD) of National Center for Advancing Translational Sciences (NCATS), USA.)

How is Non-Syndromic Hearing Loss and Deafness Diagnosed?

Non-Syndromic Hearing Loss and Deafness is diagnosed on the basis of the following information:

• Complete physical examination
• Thorough medical history evaluation
• Assessment of signs and symptoms
• Hearing (audiometry) 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 Non-Syndromic Hearing Loss and Deafness?

• The most significant complication of Non-Syndromic Hearing Loss and Deafness includes 
• Complications may occur with or without treatment, and in some cases, due to treatment also

How is Non-Syndromic Hearing Loss and Deafness Treated?

There is no cure for Non-Syndromic Hearing Loss and Deafness, 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 Non-Syndromic Hearing Loss and Deafness be Prevented?

Currently, Non-Syndromic Hearing Loss and Deafness (DFNB1) 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 Non-Syndromic Hearing Loss and Deafness? (Outcomes/Resolutions)

• The prognosis of Non-Syndromic Hearing Loss and Deafness 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 Non-Syndromic Hearing Loss and Deafness:

• Non-Syndromic Hearing Loss and Deafness is also known by the following additional name(s): Connexin 26 Linked Deafness

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

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