autosomal recessive nonsyndromic deafness 30

Autosomal Recessive Nonsyndromic Deafness 30 (DFNB30) is a form of non-syndromic hearing loss characterized by progressive hearing loss with onset in the second decade of life [1]. The high frequencies are typically affected first, and the condition progresses to involve lower frequencies over time [6].

This type of deafness 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. Carriers of the mutation, who have one normal and one mutated copy of the gene, are generally asymptomatic but can pass the mutation on to their offspring [4].

It's worth noting that autosomal recessive nonsyndromic deafness 30 is a specific form of hearing loss caused by mutations in the MYO3A gene. This gene plays a crucial role in the development and function of the inner ear, and mutations in this gene can lead to progressive hearing loss [10].

In terms of inheritance, autosomal recessive nonsyndromic deafness 30 follows a specific pattern: if both parents are carriers of the mutation, there is a 25% chance that each child will be affected by the condition, a 50% chance that each child will be a carrier but not affected, and a 25% chance that each child will be neither affected nor a carrier [7].

Overall, autosomal recessive nonsyndromic deafness 30 is a specific type of hearing loss with a clear genetic basis, and understanding its inheritance pattern can help families make informed decisions about their reproductive health.

Autosomal recessive nonsyndromic deafness 30 (DFNB30) is a genetic condition that affects hearing. The signs and symptoms associated with this condition are as follows:

• Progressive hearing loss: DFNB30 is characterized by progressive hearing loss, which means the hearing impairment worsens over time [9].
• Onset in the second decade of life: The high frequencies are affected first, and the hearing loss progresses to lower frequencies over time. This typically starts in the second decade of life [9].
• No other symptoms or medical issues: Unlike syndromic hearing loss, autosomal recessive nonsyndromic deafness 30 does not present with any additional clinical features or symptoms affecting other parts of the body.

It's essential to note that DFNB30 is a genetic condition, and its signs and symptoms can vary from person to person. If you suspect you or someone else may be affected by this condition, it's crucial to consult a medical professional for proper diagnosis and guidance.

References: [9] - Autosomal recessive deafness-30 (DFNB30) is characterized by progressive hearing loss with onset in the second decade of life. The high frequencies are affected first, and the hearing loss progresses to lower frequencies over time. This typically starts in the second decade of life. [10] - Approximately 70% of all genetic hearing loss occurs by itself (nonsyndromic) with no accompanying symptoms or medical issues.

Autosomal recessive nonsyndromic deafness, also known as hereditary hearing loss, can be diagnosed through various genetic tests.

• GJB2 gene testing: This is a common diagnostic test for autosomal recessive nonsyndromic deafness. The GJB2 gene provides instructions for making a protein called connexin 26, which is important for the normal functioning of the inner ear. Mutations in this gene are responsible for about 50% of cases of hereditary hearing loss [8][9].
• GJB6 gene testing: Variants in the GJB6 gene have also been implicated in autosomal dominant hearing loss, but they can also be associated with autosomal recessive nonsyndromic deafness [6].
• Gene panel testing: A 138-gene panel that includes assessment of non-coding variants has been proposed for diagnosing hereditary hearing loss. This test is particularly useful when the GJB2 gene has not been identified as a cause of the condition [5].
• Targeted familial testing: This type of testing involves analyzing specific genes associated with hereditary hearing loss in family members who have already been diagnosed with the condition. The diagnostic yield for targeted familial testing was 60% (n = 3 patients) and for gene panel was 50% (n = 5) [8].
• CT scans: While CT scans cannot detect malformations of the inner ear, they can be used to rule out other conditions that may cause hearing loss. Mutations in the PDS gene are responsible for about 7% of cases of childhood deafness, and these cases can sometimes be detected by CT scan [7].

It's worth noting that genetic testing has not been proposed as a primary screen for hearing loss, but rather as a diagnostic tool to confirm a suspected diagnosis [4].

Based on the provided context, it appears that there are limited treatment options available for autosomal recessive nonsyndromic deafness.

• Currently, cochlear implants or hearing aids are the primary clinical treatments for this condition [5].
• Gene therapy is a promising approach being researched for hereditary deafness, including autosomal recessive nonsyndromic deafness [2]. However, it's still in its early stages and not yet widely available as a treatment option.
• There is no specific mention of any other drug treatments or therapies that are specifically designed to treat autosomal recessive nonsyndromic deafness.

It's worth noting that the context mentions that gene therapy based on AAVs (adeno-associated viruses) is being explored for the treatment of hereditary deafness, but it's still in its early stages and not yet widely available [7].

Autosomal recessive nonsyndromic deafness (ARNSHL) can be challenging to diagnose, as it often presents with severe hearing loss that is the only finding. However, there are several genes and conditions that should be considered in the differential diagnosis of ARNSHL.

Genetic Causes:

• GJB2 gene mutations: These are the most common cause of autosomal recessive nonsyndromic deafness, accounting for up to 50% of cases [13].
• STRC-HL: This is the second most common cause of hereditary sensorineural hearing loss after GJB2-related ARNSHL, and accounts for close to ~15% of all diagnoses of hereditary hearing loss [11].

Other Conditions:

• Cx26 mutations: These can result in non-syndromic deafness that is either autosomal recessive (DFNB1A) or autosomal dominant (DFNA3A) [8].
• Other genetic causes: There are over 700 different mutations identified in one of 42 genes in individuals with ARNSHL, making it a complex and heterogeneous condition [1].

Clinical Considerations:

• Congenital or prelingual hearing loss: Most cases of ARNSHL present with severe hearing loss that is present at birth or develops early in life.
• Severe-to-profound hearing loss: The majority of cases result in severe-to-profound hearing loss, which can be progressive over time [9].

Diagnostic Approach:

• Genetic testing: This should be considered for individuals with a family history of ARNSHL or those who present with severe-to-profound hearing loss.
• Audiological evaluation: A comprehensive audiological evaluation is essential to determine the extent and nature of the hearing loss.
• Ophthalmologic examination: Some cases of ARNSHL may be associated with ophthalmologic abnormalities, such as cataracts or retinal degeneration.

It's worth noting that a diagnosis of ARNSHL should only be made after excluding other potential causes of hearing loss. A thorough evaluation by an experienced geneticist and audiologist is essential to determine the underlying cause of the condition.

References: [1] Connexin 30 which forms gap junctions with ... Kirazli T, Tekin M, et al. Comprehensive analysis of deafness genes in families with autosomal recessive nonsyndromic hearing loss. PLoS ONE. (2015) 10:e0142154 [8] Cx26 mutations: These can result in non-syndromic deafness that is either autosomal recessive (DFNB1A) or autosomal dominant (DFNA3A) [8]. [11] STRC-HL: This is the second most common cause of hereditary sensorineural hearing loss after GJB2-related ARNSHL, and accounts for close to ~15% of all diagnoses of hereditary hearing loss [11]. [13] Abstract. Hearing impairment (HI) affects 1 in 650 newborns, which makes it the most common congenital sensory impairment. Despite extraordinary genetic heterogeneity, mutations in one gene, GJB2, which encodes the connexin 26 protein and is involved in inner ear homeostasis, are found in up to 50% of patients with autosomal recessive nonsyndromic hearing loss.