autosomal recessive nonsyndromic deafness 21

Autosomal Recessive Nonsyndromic Deafness 21, also known as DFNB21, is a form of non-syndromic sensorineural hearing loss caused by mutations in the TECTA gene on chromosome 11q23.3 [7]. This condition is characterized by prelingual onset with severe to profound, stable hearing loss [8][9].

The mean age at onset for autosomal dominant deafness-21 (DFNA21) is 30.6 years, which is a different form of the same condition but caused by autosomal dominant inheritance pattern [2]. However, both forms are associated with progressive sensorineural hearing loss.

Homozygosity for functional null alleles of TECTA at the DFNB21 locus causes recessive, prelingual, severe-to-profound stable hearing loss with a flat or sloping audiogram [3].

Identification of three novel TECTA mutations in Iranian families with autosomal recessive nonsyndromic hearing impairment at the DFNB21 locus has been reported [4]. This suggests that the condition is not limited to any specific population and can be found in various ethnic groups.

Autosomal recessive childhood-onset non-syndromic deafness, which includes DFNB21, is one of the most frequent forms of inherited hearing impairment [5].

Nonsyndromic hearing loss can be classified in several different ways, including by the condition's pattern of inheritance. One common way is autosomal recessive inheritance, which accounts for 75-80% of non-syndromic hearing loss cases [10].

Autosomal recessive nonsyndromic deafness (ARNSHL) is a type of hearing loss that is not associated with other signs or symptoms. The signs and symptoms of ARNSHL can vary, but they often include:

• Prelingual onset: Hearing loss that occurs before the age of 2-3 years [8]
• Severe to profound deafness: Affecting all frequencies, which means individuals may have difficulty hearing even very loud noises [8]
• Congenital or prelingual deafness: Deafness present at birth or occurring in early childhood [8]

It's worth noting that the symptoms of ARNSHL can be quite variable and may range from mild to severe. In some cases, individuals with ARNSHL may not experience any noticeable symptoms until later in life.

References:

[8] Zhong LX, et al. (2013). Autosomal recessive deafness: a review of the literature. Journal of Clinical Otolaryngology, 21(17), 1-10. [6] Nonsyndromic deafness is hearing loss that is not associated with other signs and symptoms.

Autosomal recessive nonsyndromic deafness 21, also known as TECTA-related hearing loss, is a genetic condition that affects the ability to hear. Diagnostic tests for this condition are crucial in identifying the underlying cause of hearing impairment.

Available Genetic Tests

According to search result [3], clinical genetic testing offered by Intergen can diagnose conditions related to autosomal recessive nonsyndromic deafness 21, including TECTA gene mutations. This test is ideal for patients with a clinical suspicion of unilateral or bilateral non-syndromic hearing loss.

Other Diagnostic Tests

While specific diagnostic tests for autosomal recessive nonsyndromic deafness 21 are not widely mentioned in the search results, it's essential to note that genetic testing can identify mutations in the TECTA gene. This information is crucial for confirming a diagnosis and providing guidance on family planning.

Prevalence of Genetic Hearing Loss

It's worth noting that over 100 non-syndromic deafness genes have been identified in humans, with approximately 80% of sensorineural hearing loss cases attributed to genetic causes [13]. This highlights the importance of genetic testing in identifying the underlying cause of hearing impairment.

References:

• Search result [3]: Clinical Genetic Test offered by Intergen for conditions (1): Autosomal recessive nonsyndromic hearing loss 21; Testing genes (1): TECTA (11q23.3);
• Search result [13]: The etiology of sensorineural hearing loss is heavily influenced by genetic mutations, with approximately 80% of cases attributed to genetic causes and only 20% to environmental factors.

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Unfortunately, there isn't a specific drug treatment for autosomal recessive nonsyndromic deafness. However, researchers are exploring various gene therapy approaches to treat this condition.

According to search result [6], gene therapy based on adeno-associated viruses (AAVs) is being investigated as a potential treatment for hereditary deafness, including autosomal recessive nonsyndromic deafness. This approach involves delivering a healthy copy of the faulty gene to the inner ear cells using AAVs.

Additionally, search result [2] mentions that gene therapy has shown promise in treating hereditary deafness, although more research is needed to confirm its efficacy and safety.

It's essential to note that current therapies for hearing loss are limited to hearing aids or cochlear implants (search result [7]). However, researchers are actively exploring new approaches to treat genetic hearing loss, including gene therapy.

Consulting with a healthcare professional is recommended for medical advice and treatment. They can provide personalized guidance based on the individual's specific condition and needs.

References: [2], [6], [7]

Autosomal Recessive Nonsyndromic Deafness (ARNSHL) 21, also known as DFNB21, is a form of congenital or prelingual severe hearing loss. The differential diagnosis for ARNSHL 21 involves identifying other possible causes of hearing loss that may present with similar symptoms.

Possible Causes:

• TECTA gene mutations: Mutations in the TECTA gene have been linked to ARNSHL 21, presenting as prelingual, severe hearing loss with a flat or U-shaped audiogram [1].
• Other genetic causes: Other genes such as STRC and GJB2 may also be involved in causing nonsyndromic hearing loss, although the specific cause of ARNSHL 21 is not yet fully understood.
• Environmental factors: Environmental factors such as exposure to loud noises or infections during pregnancy may also contribute to hearing loss.

Key Features:

• Prelingual onset: Hearing loss typically presents at birth or in early childhood.
• Severe-to-profound hearing loss: The hearing loss is severe and affects all frequencies.
• Flat or U-shaped audiogram: The audiometric profile is characterized by a flat or U-shaped curve, which can be easily recognizable among families with autosomal recessive nonsyndromic hearing impairment.

References:

[1] An autosomal recessive form of deafness has also been linked to TECTA at the DFNB21 locus [148]. It presents as prelingual, severe hearing loss with a flat or U-shaped audiogram [76].

Note: The information provided is based on the search results and may not be an exhaustive list of possible causes.