autosomal dominant nonsyndromic deafness 77

Autosomal dominant nonsyndromic deafness 77 (ADND77) is a form of hearing loss that affects high frequencies, typically beginning in the second to third decades of life [1]. This condition is characterized by progressive hearing loss, which means it worsens over time [2].

The symptoms of ADND77 include bilateral, postlingual, mild-to-severe sensorineural hearing loss, meaning that both ears are affected and the hearing loss occurs after language development has taken place [3]. The hearing loss in ADND77 is typically moderate to profound, indicating a significant reduction in hearing ability [4].

ADND77 is caused by a heterozygous mutation in the ABCC1 gene on chromosome 16p13.11 [5][6]. This genetic mutation leads to the development of hearing loss, but it does not cause any other signs or symptoms, making it a nonsyndromic condition [7].

It's worth noting that ADND77 is inherited in an autosomal dominant pattern, meaning that if one parent has the condition, each child has a 50% chance of inheriting it [8].

Autosomal dominant nonsyndromic deafness 77 (DFNA77) is a form of progressive neurosensory hearing loss that affects high frequencies, typically beginning in the second to third decade of life [4]. The symptoms and signs associated with this condition are as follows:

• Progressive hearing loss: DFNA77 is characterized by a gradual decline in hearing ability, particularly affecting high-frequency sounds [4].
• High-frequency hearing loss: The condition

Autosomal dominant nonsyndromic hearing loss (ADNSHL) can be diagnosed through various genetic tests. Here are some diagnostic tests that may be used to identify the condition:

• Targeted mutation analysis: This test involves analyzing specific genes known to be associated with ADNSHL, such as GJB2 and MYO6 [7].
• Mutation scanning/screening and sequence analysis of selected exons: This test is used to detect mutations in specific regions of genes that are known to cause ADNSHL [7].
• Sequence analysis: entire coding region: This test involves analyzing the entire coding region of a gene to identify any mutations that may be causing ADNSHL [7].

It's worth noting that the diagnostic yield of these tests can vary depending on the specific genetic basis of the condition. For example, a study found that targeted mutation analysis had a diagnostic yield of 66% for DFNB1-associated hearing impairment [8].

In addition to these genetic tests, clinical evaluation by an expert in genetics and hearing loss is also essential for diagnosing ADNSHL [2]. This may involve a comprehensive medical history, physical examination, and auditory testing.

References: [7] - Targeted mutation analysis [8] - Diagnostic testing for DFNB1-associated hearing impairment

Based on the provided context, it appears that there are currently no specific drug treatments available for autosomal dominant nonsyndromic deafness.

However, researchers are exploring gene therapy as a potential treatment option. Gene replacement, in particular, is being investigated as a strategy to treat autosomal dominant hearing loss. This approach involves delivering exogenous genes to provide sufficiently functional protein and has shown promise in treating recessive genetic diseases and dominant genetic diseases with insufficient single allele dosage.

For example, an interim analysis of a single-arm trial in 5 children with hereditary deafness shows that binaural AAV gene therapy is safe and leads to hearing improvement up to 13–26 weeks of follow-up [12]. Additionally, research on using adeno-associated virus (AAV)-mediated editing to treat human autosomal dominant hearing loss has shown promising results [13].

It's essential to note that these findings are still in the early stages of research and more studies are needed to confirm their efficacy. Furthermore, gene therapy is not yet a widely available treatment option for autosomal dominant nonsyndromic deafness.

References:

• [12] An interim analysis of a single-arm trial in 5 children with hereditary deafness shows that binaural AAV gene therapy is safe and leads to hearing improvement up to 13–26 weeks of follow-up.
• [13] Research on using adeno-associated virus (AAV)-mediated editing to treat human autosomal dominant hearing loss has shown promising results.

Autosomal dominant nonsyndromic deafness 77 (DFNA2) is a form of hearing loss that is inherited in an autosomal dominant pattern, meaning that only one copy of the mutated gene is necessary to express the condition. The differential diagnosis for DFNA2 involves considering other forms of autosomal dominant non-syndromic hearing loss.

Key Features:

• Postlingual onset: Hearing loss typically occurs after language development has taken place.
• Progressive and high-frequency: Hearing loss tends to progress over time, with higher frequencies being affected first.
• Bilateral and symmetric: Hearing loss is usually present in both ears and affects both sides equally.

Differential Diagnosis:

• Other forms of autosomal dominant non-syndromic hearing loss: These include DFNA8/12 (TECTA gene), DFNA22 (MYO6 gene), and others, which may have similar clinical features.
• Autosomal recessive non-syndromic hearing loss: This form of hearing loss is typically prelingual and more severe than autosomal dominant non-syndromic hearing loss.

Diagnostic Considerations:

• Family history: A positive family history of hearing loss, particularly in a first-degree relative, increases the likelihood of an autosomal dominant inheritance pattern.
• Genetic testing: Genetic testing for specific genes associated with autosomal dominant non-syndromic hearing loss (e.g., KCNQ4) may be necessary to confirm the diagnosis.

References:

• [7] Deafness, autosomal recessive 77 is a form of non-syndromic deafness that typically presents with preserved low-frequency hearing in childhood, progressing to ...
• [11] In general, autosomal dominant nonsyndromic hearing loss is postlingual, progressive, and high frequency. Exceptions to this generalization and/or distinctive features associated with selected genes are summarized in Table 4.
• [14] An estimated 70% of genetic hearing loss is nonsyndromic. Nonsyndromic hearing loss may be transmitted as an autosomal recessive (~80%), autosomal dominant (~15%), or X-linked trait (~1%).