Usher syndrome type 2A

Usher Syndrome Type 2A: A Rare Genetic Condition

Usher syndrome type 2A is a rare genetic condition characterized by hearing loss from birth and progressive vision loss that usually begins in adolescence or adulthood. This condition is caused by mutations in the USH2A gene, which affects the development of the inner ear and retina.

Key Features:

• Hearing Loss: Hearing loss is present at birth and can range from mild to severe.
• Vision Loss: Vision loss typically begins in adolescence or adulthood and progresses over time. Night vision loss often occurs first, followed by blind spots in the side (peripheral) vision.
• Retinitis Pigmentosa: The condition is associated with retinitis pigmentosa, a degenerative eye disease that affects the retina.

Prevalence:

Usher syndrome type 2A is one of the most common forms of Usher syndrome, accounting for up to 95% of cases in the United States. It is an autosomal recessive condition, meaning that a person must inherit two copies of the mutated gene (one from each parent) to develop the condition.

Genetic Counseling:

Individuals with Usher syndrome type 2A have a 25% chance of passing the mutated gene to their offspring in each subsequent pregnancy. Genetic counseling can help families understand the risks and make informed decisions about reproduction.

References:

• [5] Usher syndrome is a genetic condition that causes hearing loss, vision loss, and sometimes balance/vestibular problems.
• [10] Usher syndrome type 2A is a genetic condition characterized by hearing loss from birth and progressive vision loss that usually begins in adolescence or adulthood.
• [15] Usher syndrome type II (USH2) is characterized by congenital, bilateral sensorineural hearing loss and retinitis pigmentosa.

Common Signs and Symptoms of Usher Syndrome Type 2A

Usher syndrome type 2A is a genetic disorder that primarily affects hearing and vision. The main symptoms of this condition are:

• Hearing Loss: People with Usher syndrome type 2A experience varying degrees of hearing loss, which can range from mild to severe.
• Retinitis Pigmentosa (RP): RP is a condition that affects the retina, leading to progressive vision loss. In people with Usher syndrome type 2A, RP typically develops during late adolescence or early adulthood.
• Normal Balance: Unlike other forms of Usher syndrome, individuals with type 2A do not experience difficulties with balance caused by inner ear problems.

Other Possible Symptoms

While the primary symptoms of Usher syndrome type 2A are hearing loss and RP, some people may also experience:

• Night Blindness: Difficulty seeing in low light conditions
• Constricted Visual Field (Tunnel Vision): A narrowed field of vision
• Decreased Visual Acuity: Gradual decline in visual sharpness

Important Note

It's essential to note that the severity and progression of symptoms can vary significantly among individuals with Usher syndrome type 2A. DNA testing is the only reliable way to determine the true genetic type, which can help guide treatment and management decisions.

References:

• [1] Type 2A does not have difficulties with balance caused by inner ear problems.
• [10] The degree of hearing loss varies within and among families with this condition.
• [14] Symptoms depend on the type of Usher syndrome. But they often include problems with hearing or deafness, balance, and eyesight or blindness.

Diagnostic Tests for Usher Syndrome Type 2A

Usher syndrome type 2A is a genetic condition characterized by hearing loss from birth and progressive vision loss that usually begins in adolescence or adulthood. To diagnose this condition, several diagnostic tests can be performed.

• Electronystagmography (ENG): This test measures the response of the retina cells to light and is commonly utilized in the diagnosis of Usher syndrome type 2A [5].
• Electroretinogram (ERG): An ERG measures the response of the retina cells to light and can help confirm a diagnosis of Usher syndrome type 2A [6].
• Eye tests: Tests such as visual function tests, dilated eye exams, ocular photography, and ERGs can be used to check for retinitis pigmentosa, which is a hallmark of Usher syndrome type 2A [10][15].
• Hearing tests: Hearing tests are also essential in diagnosing Usher syndrome type 2A, as hearing loss from birth is a characteristic symptom [8][9].
• Genetic testing: Genetic testing can help confirm the diagnosis by identifying mutations in one of the genes associated with Usher syndrome type 2A, such as USH2A or PDZD7 [4][14].

These diagnostic tests can be performed by a healthcare provider to diagnose Usher syndrome type 2A. It's essential to note that a comprehensive evaluation by a specialist is necessary for an accurate diagnosis.

References: [1] - Not relevant [2] - Not directly relevant, but provides general information about Usher syndrome. [3] - Provides information about Usher syndrome type 2, which is related to Usher syndrome type 2A. [4] - Mentions genetic testing as a diagnostic tool for Usher syndrome. [5] - Describes Electronystagmography (ENG) as a test used in the diagnosis of Usher syndrome type 2A. [6] - Discusses Electroretinogram (ERG) and its use in diagnosing Usher syndrome type 2A. [7] - Not relevant [8] - Lists hearing tests as part of the diagnostic process for Usher syndrome type 2A. [9] - Mentions hearing tests as a diagnostic tool for Usher syndrome. [10] - Describes the symptoms and diagnosis of Usher syndrome type 2A, including retinitis pigmentosa. [11] - Discusses the diagnosis of USH2 using electrophysiologic and subjective tests. [12] - Not directly relevant, but provides general information about healthcare providers and diagnostic testing. [13] - Describes a scenario where a person has two Usher genes but does not exhibit all symptoms. [14] - Provides general information about Usher syndrome, including genetic testing as a diagnostic tool. [15] - Lists the requirements for participating in a study on rod-cone degeneration and mentions visual function tests, dilated eye exams, ocular photography, and ERGs.

Current Status of Drug Treatment for Usher Syndrome Type 2A

Usher syndrome type 2A (USH2A) is a genetic disorder that affects the eyes and ears, leading to progressive vision loss and hearing impairment. Currently, there is no cure or effective treatment available for USH2A.

• According to search result [6], Usher syndrome (USH) is the most common form of deaf-blindness, with an estimated prevalence of 4.4 to 16.6 per 100000 people worldwide.
• As stated in search results [8] and [9], there is no effective treatment available for USH2A.
• Search result [10] also confirms that currently, no treatment exists for USH2A.

Research and Development of New Therapies

However, researchers are actively exploring new therapeutic approaches to address the underlying causes of Usher syndrome. For example:

• A study published in search result [2] provides novel data on the read-through efficacy of Ataluren on a nonsense mutation in the USH2A gene.
• Search result [4] mentions preclinical evidence suggesting AAV-based gene replacement therapies or AO strategies may be applicable in the inner ear as well as the eye, which could provide potential therapeutic options for Usher syndrome.

Investigational Therapies

Several investigational RNA-based oligonucleotides and gene therapies are being developed to address the underlying cause of vision loss associated with Usher syndrome. For example:

• QR-421a is a first-in-class investigational RNA-based oligonucleotide designed to address the underlying cause of the vision loss associated with Usher syndrome (search result [1]).
• Editas Medicine, as mentioned in search result [3], has announced the utilization of a new therapeutic, EDIT-102, to target Usher type 2A.

While these investigational therapies hold promise, it is essential to note that they are still in the experimental stages and have not yet been proven effective in humans. Further research and clinical trials are necessary to determine their safety and efficacy.

Conclusion

In summary, there is currently no effective treatment available for Usher syndrome type 2A. However, researchers are actively exploring new therapeutic approaches, including investigational RNA-based oligonucleotides and gene therapies, which may potentially address the underlying causes of vision loss associated with this condition.

Differential Diagnoses for Usher Syndrome Type 2A

Usher syndrome type 2A (USH2A) is a genetic condition characterized by hearing loss from birth and progressive vision loss that usually begins in adolescence or adulthood. When diagnosing USH2A, it's essential to consider other conditions that may present with similar symptoms.

Conditions to Consider:

• Oculo-acoustic syndromes associated with peroxysomal gene alterations (Heimler syndrome with enamel dysplasia): This condition is characterized by hearing loss and eye abnormalities, but it also involves enamel dysplasia, which is not typically seen in USH2A.
• Metabolic disorders: Certain metabolic disorders can cause hearing loss and vision problems, but they are usually associated with other systemic symptoms.
• Nonsyndromic Hearing Loss; Deafness-Dystonia: This condition presents with hearing loss and dystonia (involuntary muscle contractions), which is not typically seen in USH2A.

Key Points to Consider:

• Genetic testing: Genetic testing can help confirm the diagnosis of USH2A by identifying mutations in the USH2A gene.
• Clinical features: The clinical features of USH2A, such as congenital hearing loss and progressive vision loss, should be carefully evaluated to rule out other conditions.

References:

• [3] Usher syndrome type II can result from mutations in three genes; USH2A gene mutations account for most cases of type II.
• [4] Differential diagnoses include oculo-acoustic syndromes associated with peroxysomal gene alterations (Heimler syndrome with enamel dysplasia), metabolic disorders, and nonsyndromic Hearing Loss; Deafness-Dystonia.
• [14] An Usher syndrome multigene panel or a more comprehensive multigene panel that includes the genes listed in Table 1 and other genes of interest is most likely to identify the genetic cause of the condition while limiting identification of benign variants.