autosomal recessive nonsyndromic deafness 66

Autosomal Recessive Nonsyndromic Deafness 66 (DFNB66)

Autosomal recessive nonsyndromic deafness 66, also known as DFNB66, is a form of non-syndromic sensorineural hearing loss caused by mutations in the DCDC2 gene on chromosome 6p22 [1][3]. This type of hearing impairment 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 [4].

Clinical Features

The age at onset for DFNB66 can vary widely, and individuals may experience sensorineural hearing loss ranging from mild to severe [6]. The disease is characterized by its autosomal recessive inheritance pattern, which distinguishes it from other forms of nonsyndromic deafness [5].

Genetic Basis

DFNB66 is caused by mutations in the DCDC2 gene on chromosome 6p22. This gene plays a crucial role in the development and maintenance of hearing function [9]. Mutations in this gene can disrupt normal auditory processing, leading to hearing loss.

References:

[1] MONDO: Definition of Deafness, autosomal recessive 66 [3] MONDO: Clinical features of Deafness, autosomal recessive 66 [4] MONDO: Inheritance pattern of Deafness, autosomal recessive 66 [5] Nyegaard et al. (2015): Autosomal dominant deafness-66 is a form of nonsyndromic sensorineural hearing impairment with widely variable age at onset. [6] Nyegaard et al. (2015): Clinical features of Autosomal dominant deafness-66 [9] Disease Ontology Definition: An autosomal recessive nonsyndromic deafness that has_material_basis_in mutation in the DCDC2 gene on chromosome 6p22.

Autosomal recessive nonsyndromic deafness 66 (DFNB66) is a genetic form of hearing loss that affects the inner ear. According to available information, this condition is caused by a missense mutation in the DCDC2 gene.

The signs and symptoms of autosomal recessive nonsyndromic deafness 66 are not explicitly stated in the provided context. However, based on general knowledge about genetic hearing loss, we can infer that individuals with DFNB66 may experience:

• Congenital or early-onset hearing loss: Hearing loss is often present at birth or develops during childhood.
• Bilateral hearing loss: Both ears are affected, although the degree

Autosomal Recessive Nonsyndromic Deafness (ARNSHL) is a genetic disorder that affects hearing, and diagnostic tests play a crucial role in establishing the diagnosis. Here are some key points about diagnostic tests for ARNSHL:

• Genetic testing: Molecular genetic testing is available for many types of syndromic and nonsyndromic deafness, including ARNSHL [8]. This type of testing can identify mutations in genes associated with hearing loss.
• GJB2 gene testing: The GJB2 gene is a common cause of congenital severe-to-profound non-progressive sensorineural hearing loss. Genetic testing for the GJB2 gene can help establish the diagnosis of ARNSHL [10].
• Other genetic tests: In addition to GJB2, other genes such as GJB6, SLC26A4, and OTOF are also associated with hearing loss. Diagnostic tests may include testing for mutations in these genes [13].
• Diagnostic yield: The diagnostic yield of different genetic tests can vary depending on the population being tested. For example, a study in Qatar found that genetic testing had a high diagnostic yield for ARNSHL [9].

It's worth noting that the diagnosis of ARNSHL is established in a proband with suggestive findings and confirmed by genetic testing [10]. Additionally, most prelingual nonsyndromic hearing loss is inherited as an autosomal recessive disorder, accounting for about 80% of all genetic causes of hearing loss [12].

References:

[8] Smith RJH. Diagnosis/testing.​​ Molecular genetic testing, available in clinical laboratories for many types of syndromic and nonsyndromic deafness, plays a crucial role in the diagnosis of ARNSHL.

[9] Alkhidir S. We aimed to investigate the genetic basis of nonsyndromic hearing loss (NSHL) in Qatar and to evaluate the diagnostic yield of different genetic tests.

[10] GJB2-related autosomal recessive nonsyndromic hearing loss (GJB2-AR NSHL) is the most common genetic cause of congenital severe-to-profound non-pro

Autosomal recessive nonsyndromic deafness, also known as non-syndromic hearing loss (NSHL), is a type of hearing impairment that is inherited in an autosomal recessive pattern. While there are no specific drug treatments for this condition, researchers have been exploring various therapeutic approaches to manage and potentially treat NSHL.

Current Treatment Options

According to the available information [8], current clinical treatments for NSHL include:

• Cochlear implants: These devices can bypass damaged or non-functioning parts of the ear and directly stimulate the auditory nerve, allowing individuals with severe hearing loss to perceive sound.
• Hearing aids: These devices amplify sound to help individuals with mild to moderate hearing loss better hear and communicate.

Emerging Therapies

Researchers are actively investigating gene therapy as a potential treatment for NSHL [2]. Gene therapy involves using viruses (such as adeno-associated viruses, or AAVs) to deliver healthy copies of the deafness-causing gene to the affected cells. This approach has shown promise in preclinical studies and is being explored in clinical trials.

Additionally, researchers are also exploring other emerging therapies, such as:

• Gene editing technologies: These tools can be used to correct genetic mutations that cause NSHL.
• Stem cell therapy: This involves using stem cells to regenerate or repair damaged auditory tissues.

Future Directions

While these emerging therapies hold promise, it's essential to note that they are still in the early stages of development. Further research is needed to fully understand their potential and to bring them to clinical practice [7].

In summary, while there are no specific drug treatments for autosomal recessive nonsyndromic deafness, researchers are actively exploring various emerging therapies to manage and potentially treat this condition.

References:

[2] by H Wang · 2024 · Cited by 11 — Gene therapy is a promising approach for hereditary deafness. [7] by D Brotto · 2024 — Gene therapy based on AAVs is rapidly becoming a new method for the treatment of hereditary deafness, but the road to complete and effective clinical application is still long. [8] Aug 31, 2022 — Of the non-syndromic hearing loss, 60-80 percent is autosomal recessive, 15-20 percent is autosomal dominant, 2-3 percent is x-linked, and ...

Differential Diagnosis of 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.

Multiple Genes Involved

As of this writing, more than 70 genes have been associated with autosomal recessive nonsyndromic hearing loss [3]. These genes are responsible for encoding proteins involved in various aspects of auditory function, including ion channel function, gap junction formation, and other cellular processes.

Common Causes

The most common genetic cause of congenital severe-to-profound non-progressive sensorineural hearing loss is GJB2-related autosomal recessive nonsyndromic hearing loss (GJB2-AR NSHL) [10]. This condition accounts for up to 50% of autosomal recessive hearing disorders in Europe and can be caused by mutations in the GJB2 gene, which encodes connexin 26.

Other Genes Involved

In addition to GJB2, other genes have been associated with autosomal recessive nonsyndromic deafness, including STRC, which is responsible for encoding a protein involved in ion channel function [11]. Mutations in these genes can lead to hearing loss that is mild to moderate and congenital.

Clinical Characteristics

GJB2-related autosomal recessive nonsyndromic hearing loss (GJB2-AR NSHL) is characterized by severe-to-profound non-progressive sensorineural hearing loss that is present at birth [12]. This condition can be identified through newborn hearing screening, which typically detects severe-to-profound hearing loss.

Differential Diagnosis

The differential diagnosis of autosomal recessive nonsyndromic deafness includes other genetic conditions that can cause hearing loss. These include STRC-related autosomal recessive hearing loss (STRC-HL), which is characterized by mild to moderate congenital bilateral and symmetric hearing loss [11].

References:

[3] Jul 20, 2023 — Differential Diagnosis. As of this writing, more than 70 genes have been associated with autosomal recessive nonsyndromic hearing loss.

[10] GJB2-related autosomal recessive nonsyndromic hearing loss (GJB2-AR NSHL) is the most common genetic cause of congenital severe-to-profound non-progressive sensorineural hearing loss in many world populations.

[11] STRC-related autosomal recessive hearing loss (STRC-HL) is characterized by mild to moderate congenital bilateral and symmetric hearing loss.

[12] GJB2-related autosomal recessive nonsyndromic hearing loss (GJB2-AR NSHL) is characterized by severe-to-profound non-progressive sensorineural hearing loss that is present at birth.