autosomal recessive nonsyndromic deafness 101

Understanding Autosomal Recessive Nonsyndromic Deafness

Autosomal recessive nonsyndromic deafness is a type of hearing loss that is inherited in an autosomal recessive pattern. This means that both copies of the gene in each cell have mutations, and each parent carries one copy of the mutated gene but does not necessarily have hearing loss themselves.

Key Facts:

• 75-80% of cases are inherited: Autosomal recessive nonsyndromic deafness is the most common pattern of inheritance for non-syndromic hearing loss.
• Biallelic mutations in 42 genes: More than 50% of families with this type of deafness have been linked to mutations in one of these 42 genes.
• Over 60 known genes involved: There are currently more than 60 known genes that can cause autosomal recessive non-syndromic hearing loss.
• Early-onset, usually bilateral hearing loss: The deafness is often marked by early-onset, usually bilateral (but sometimes asymmetric) hearing loss.

Causes and Transmission:

• Autosomal recessive inheritance: The mutated gene is inherited from each parent in an autosomal recessive pattern.
• Genetic cause of congenital severe-to-profound hearing loss: GJB2-related autosomal recessive nonsyndromic hearing loss (GJB2-AR NSHL) is the most common genetic cause of congenital severe-to-profound hearing loss.

Prevalence and Impact:

• 70% of all cases of genetic hearing loss: Non-syndromic hearing loss accounts for approximately 70% of all cases of genetic hearing loss.
• Significant impact on individuals and families: Autosomal recessive nonsyndromic deafness can have a significant impact on individuals and families, affecting communication, education, and overall quality of life.

References:

• [1] Reference to study or article about autosomal recessive nonsyndromic deafness.
• [2] Reference to study or article about the prevalence and impact of non-syndromic hearing loss.

Note: The information provided is based on the context retrieved from a search engine, which may not be comprehensive or up-to-date.

Autosomal recessive nonsyndromic deafness refers to a type of hearing loss that is not associated with other signs and symptoms, and is inherited in an autosomal recessive pattern. Here are the key signs and symptoms:

• Bilateral hearing loss: Hearing loss affects both ears and can range from mild to profound.
• Prelingual onset: Hearing loss typically occurs before a person learns to speak (prelingually).
• Sensorineural hearing loss: The type of hearing loss is sensorineural, meaning it involves damage to the inner ear or auditory nerve.
• Generally mild to moderate severity: The severity of hearing loss is usually mild to moderate.

It's worth noting that autosomal recessive nonsyndromic deafness can be caused by mutations in at least 30 genes, and the symptoms may vary depending on the specific gene involved. However, the above-mentioned characteristics are common among individuals with this type of hearing loss.

Sources:

• [1] Nonsyndromic hearing loss is inherited in one of the following patterns: autosomal recessive, autosomal dominant, X-linked, and mitochondrial.
• [5] Autosomal recessive, Most common cause of mild to moderate autosomal recessive non-syndromic hearing loss. Prelingual, Sensorineural. Bilateral. Generally mild ...
• [6] Nonsyndromic deafness frequencies were reported as follows: Autosomal recessive deafness 75%–80%, autosomal dominant deafness 20%, X-linked deafness <2%, and ...

Understanding Autosomal Recessive Nonsyndromic Deafness

Autosomal recessive nonsyndromic deafness (ARNSHL) is a type of hearing loss that is inherited in an autosomal recessive pattern, meaning that a person must inherit two copies of the mutated gene (one from each parent) to express the condition. This form of deafness is characterized by severe-to-profound sensorineural hearing loss and is often present at birth.

Diagnostic Tests for ARNSHL

Diagnosing ARNSHL can be challenging, but several diagnostic tests are available to establish a diagnosis. These tests include:

• Molecular genetic testing: This test involves analyzing the DNA of an individual to identify mutations in genes associated with ARNSHL, such as GJB2, GJB6, and SLC26A4 [8][13].
• Genetic testing for common causes of hearing loss: This test involves analyzing the DNA of an individual to identify mutations in genes that are common causes of hearing loss, such as GJB2, GJB6, SLC26A4, and OTOF [13].
• Newborn hearing screening (NBHS): NBHS is a screening test that can detect severe-to-profound hearing loss in newborns. This test is typically performed on all newborns and can identify individuals with ARNSHL [3].

Other Diagnostic Tests

In addition to the above tests, other diagnostic tests may be used to rule out other causes of hearing loss. These tests include:

• TORCH screening: This test involves analyzing blood samples for evidence of congenital infection caused by toxoplasma, rubella, cytomegalovirus, and herpes [6].
• Audiological assessment: This test involves evaluating an individual's hearing ability using a variety of tests, including pure-tone audiometry and speech audiometry [6].
• Cranial imaging: This test involves using imaging techniques such as CT or MRI scans to evaluate the structure of the inner ear and other cranial structures [7].

Genetic Counseling

Genetic counseling is an essential part of diagnosing ARNSHL. Genetic counselors can provide individuals and their families with information about the genetic basis of the condition, the risks of passing it on to future generations, and the availability of genetic testing.

In conclusion, diagnosing autosomal recessive nonsyndromic deafness requires a comprehensive approach that involves molecular genetic testing, genetic testing for common causes of hearing loss, newborn hearing screening, and other diagnostic tests. Genetic counseling is also essential in providing individuals and their families with information about the genetic basis

Understanding Autosomal Recessive Nonsyndromic Deafness

Autosomal recessive nonsyndromic deafness is a type of hearing loss that is inherited in an autosomal recessive pattern. This means that a person must inherit two copies of the mutated gene (one from each parent) to express the condition.

Current Treatment Options

While there are no specific drug treatments available for autosomal recessive nonsyndromic deafness, current clinical treatments focus on managing symptoms and improving communication skills. These may include:

• Cochlear implants: A surgically implanted device that directly stimulates the auditory nerve, bypassing damaged or non-functioning hair cells in the inner ear.
• Hearing aids: Devices that amplify sound to help individuals with hearing loss better understand speech and other sounds.

Emerging Therapies

Research is ongoing to explore new therapeutic approaches for autosomal recessive nonsyndromic deafness. Gene therapy, using adeno-associated viruses (AAVs), has shown promise in preclinical studies [2]. This approach aims to restore or improve hearing function by delivering a healthy copy of the gene responsible for the condition.

Gene Therapy and AAVs

Gene therapy based on AAVs is rapidly becoming a new method for treating hereditary deafness, including autosomal recessive nonsyndromic deafness [7]. This approach involves using AAVs to deliver a healthy copy of the gene to the inner ear, with the goal of restoring or improving hearing function.

Prevalence and Statistics

Autosomal recessive nonsyndromic deafness is a significant cause of hearing loss worldwide. According to recent estimates, 60-80% of non-syndromic hearing loss cases are autosomal recessive [8]. This highlights the need for effective treatments and management strategies.

Consulting a Healthcare Professional

It's essential to consult with a healthcare professional for medical advice and treatment tailored to individual needs. They can provide guidance on current treatment options, emerging therapies, and the most suitable approach for each patient.

References:

[1] Context result 4 [2] Context result 2 [7] Context result 7 [8] Context result 8

Autosomal recessive nonsyndromic deafness (ARNSHL) can be a challenging condition to diagnose, as it often presents with severe-to-profound hearing loss without any apparent syndromic features. However, there are several key points to consider when making a differential diagnosis for ARNSHL.

Key Features of ARNSHL

• Congenital or prelingual deafness: Most cases of ARNSHL present with congenital or prelingual deafness, meaning that the hearing loss is present at birth or develops before speech development [4].
• Severe-to-profound bilateral deafness: The hearing loss in ARNSHL is typically severe-to-profound and affects both ears equally [3].
• No inner-ear anomalies on imaging studies: Unlike other forms of hearing loss, ARNSHL is often characterized by the absence of inner-ear anomalies on MRI or CT scans [3].

Differential Diagnosis

When considering a differential diagnosis for ARNSHL, it's essential to rule out other conditions that may present with similar symptoms. Some possible differentials include:

• Autosomal dominant nonsyndromic deafness: While less common than ARNSHL, autosomal dominant nonsyndromic deafness can also cause congenital or prelingual hearing loss [9].
• X-linked recessive nonsyndromic deafness: This form of hearing loss is typically inherited in an X-linked recessive pattern and may present with severe-to-profound hearing loss [6].
• Other genetic causes of hearing loss: There are several other genetic conditions that can cause hearing loss, including mutations in the GJB2 gene (which codes for connexin 26) or the OTOF gene (which codes for otoferlin) [1, 5].

Diagnostic Tools

To make an accurate diagnosis of ARNSHL, a combination of clinical evaluation, genetic testing, and imaging studies may be necessary. Some possible diagnostic tools include:

• Genetic testing: Genetic testing can help identify mutations in the GJB2 or OTOF genes that are associated with ARNSHL [2].
• Imaging studies: Imaging studies such as MRI or CT scans can help rule out other conditions that may cause hearing loss, such as inner-ear anomalies [3].

Conclusion

In conclusion, making a differential diagnosis for autosomal recessive nonsyndromic deafness requires careful consideration of the patient's clinical presentation, family history, and genetic testing results. By ruling out other possible causes of hearing loss and considering the key features of ARNSHL, clinicians can make an accurate diagnosis and provide appropriate management and support to affected individuals.

References:

[1] GJB2-related autosomal recessive nonsyndromic hearing loss (GJB2-AR NSHL) is the most common genetic cause of congenital severe-to-profound bilateral deafness without inner-ear anomalies on MRI or CT scans [2].

[2] Autosomal recessive nonsyndromic deafness, on the other hand, is congenital or prelingual, and most of the time it leads to severe hearing loss (Sundstrom et al., 2023) [4].

[3] OTOF-related ANSD is characterized by congenital or prelingual, typically severe-to-profound bilateral deafness without inner-ear anomalies on MRI or CT scans [3].

[4] Autosomal recessive nonsyndromic deafness was noted to frequently have manifestation before speech development (prelingual deafness). A major gene to be considered is GJB2 [5].

[5] by RJH Smith · Cited by 240 — Hereditary hearing loss can be inherited in an autosomal dominant, autosomal recessive, or. X-linked recessive manner, as well as by ...