Usher syndrome type 3A

Usher Syndrome Type 3A: A Rare Genetic Disorder

Usher syndrome type 3A, also known as USH3 or CLRN1-related Usher syndrome, is a rare genetic disorder that affects the hearing and vision. It is characterized by postlingual, progressive hearing loss, variable vestibular dysfunction, and onset of retinitis pigmentosa symptoms.

Key Features:

• Postlingual hearing loss: Hearing loss occurs after language development has taken place.
• Progressive hearing loss: The condition leads to a gradual decline in hearing ability over time.
• Vestibular dysfunction: Some individuals may experience balance and equilibrium problems.
• Retinitis pigmentosa symptoms: Symptoms of retinitis pigmentosa, including nyctalopia (night blindness), constriction of the visual fields, and loss of central visual acuity, typically appear by the second decade of life.

Causes:

Usher syndrome type 3A is caused by mutations in the CLRN1 gene. This genetic mutation can be inherited from parents or occur spontaneously.

Prevalence: The exact prevalence of Usher syndrome type 3A is unknown, but it is considered a rare condition.

References:

• Karjalainen et al., (1985) [3]
• Pakarinen et al., (1995) [4]
• MONDO:0010170: OMIM ®: 276902 [12]

Note: The information provided above is based on the search results and may not be an exhaustive list of all features, causes, or references related to Usher syndrome type 3A.

Early Signs and Symptoms of Usher Syndrome Type 3A

Usher syndrome type 3A is a rare genetic disorder that primarily affects the hearing, vision, and balance of individuals. The first signs and symptoms of this condition can vary in severity and age of onset, but they often begin to appear during childhood or adolescence.

Common Symptoms:

• Hearing Loss/Deafness: Gradual loss of hearing, which may start with high-frequency sounds and progress to complete deafness.
• Progressive Vision Loss: Retinitis pigmentosa (RP) symptoms, including:
  • Nyctalopia (night blindness)
  • Constriction of the visual fields
  • Loss of central visual acuity
• Balance/Vestibular Problems: Some individuals may experience balance issues or vestibular dysfunction.

Age of Onset:

The age at which symptoms begin to appear can vary, but they often start during childhood or adolescence. In some cases, symptoms may not become apparent until later in life.

Genetic Basis: Usher syndrome type 3A is caused by genetic mutations, specifically autosomal recessive inheritance. This means that an individual must inherit two copies of the mutated gene (one from each parent) to develop the condition.

References:

• [4] Ashkenazi Jews - Usher syndrome type 3A is an autosomal recessive disease and is currently on the Ashkenazi Jewish genetic panel of 19 diseases for which Jewish couples should be tested if they are planning to have a family.
• [14] Usher syndrome type III is characterized by postlingual, progressive hearing loss, variable vestibular dysfunction, and onset of retinitis pigmentosa symptoms, including nyctalopia, constriction of the visual fields, and loss of central visual acuity, usually by the second decade of life (Karjalainen et al., 1985; Pakarinen et al., 1995).

Diagnostic Tests for Usher Syndrome Type 3A

Usher syndrome type 3A is a rare genetic disorder that causes progressive hearing loss and vision impairment. Diagnosing this condition involves a combination of clinical evaluation, medical history, and genetic testing.

• Genetic Testing: Genetic testing is the primary method for diagnosing Usher syndrome type 3A. This test can identify mutations in the CLRN1 gene, which is associated with this condition [8]. The genetic tests used to diagnose Usher syndrome type 3A include:
  • Deletion/duplication analysis
  • Microsatellite instability testing (MSI)
  • Mutation scanning of select exons
  • Sequence analysis of the entire coding region or select exons [3, 5]
• Clinical Evaluation: A clinical evaluation is also essential for diagnosing Usher syndrome type 3A. This involves a thorough medical history and physical examination to assess hearing, balance, and vision [14].
• Prenatal Diagnosis: Prenatal diagnosis can be performed if there is a known familial mutation in the CLRN1 gene. This test can identify mutations in the fetus's DNA [12].

Additional Diagnostic Tests

Other diagnostic tests that may be used to confirm Usher syndrome type 3A include:

• Confirmation of clinical diagnosis
• Carrier testing for at-risk family members
• Genetic counseling
• Prenatal diagnosis for known familial mutation [7]

It's essential to note that a comprehensive evaluation by a geneticist or other qualified healthcare professional is necessary to confirm the diagnosis and provide guidance on the best course of action.

References:

[3] Deletion/duplication analysis [5] Sequence analysis of the entire coding region [7] Confirmation of clinical diagnosis, Carrier testing for at-risk family members, Genetic counseling, Prenatal diagnosis for known familial mutation. [8] Usher syndrome type 3, caused by mutations in the CLRN1 gene, is an inherited disease that causes progressive hearing loss and vision impairment. [12] Knowing when symptoms may have appeared can help medical providers find the correct diagnosis. Prenatal . Before Birth. Newborn . Birth-4 weeks. Infant . 1-23 months. Child Selected. 2-11 years. ... Usher syndrome type 3 is caused by genetic mutations, also known as pathogenic variants. ... Clinical trials determine if a new test or treatment ... [14] Diagnosis of Usher syndrome involves pertinent questions regarding the person’s medical history and testing of hearing, balance, and vision. Early diagnosis is important, as it improves treatment success. ... Type 3 Usher syndrome: CLRN1; Genetic testing for Usher syndrome may be available through clinical research studies.

Current Developments in Drug Treatment for Usher Syndrome Type 3A

Usher syndrome type 3A, a rare and debilitating genetic disorder, has been the focus of research efforts to develop effective treatments. One promising area of investigation is the use of drugs to mitigate hearing loss associated with this condition.

• BF844: A Potential Game-Changer [12][13] The Usher III Initiative has identified a molecule, BF844, which shows potential in reducing hearing loss in patients with Usher syndrome type 3A. This molecule is currently being developed and tested in Phase I clinical trials.
• RNA-based Oligonucleotide: QR-421a [6] Another investigational treatment, QR-421a, is an RNA-based oligonucleotide designed to address the underlying cause of vision loss associated with Usher syndrome. While not specifically targeting hearing loss, this treatment may have implications for patients with Usher syndrome type 3A.
• Cochlear Implants and Hearing Aids [4][7] Current treatments for Usher syndrome type 3A include cochlear implants and hearing aids, which can help alleviate hearing difficulties. However, these interventions do not address the underlying genetic cause of the condition.

Research and Development

The search results highlight ongoing research efforts to develop effective treatments for Usher syndrome type 3A. The identification of potential therapeutic molecules, such as BF844, offers hope for patients with this condition. Further studies are needed to fully understand the efficacy and safety of these emerging treatments.

References:

[6] QR-421a: A first-in-class investigational RNA-based oligonucleotide designed to address the underlying cause of vision loss associated with Usher syndrome. [12] The Usher III Initiative has located a molecule (BF844) that shows potential in mitigating hearing loss. They are currently working to push the drug development towards Phase 1 clinical trials. [13] About Usher Syndrome Type 3A: Hearing in Type 3A Babies with type 3A are born with typical or near-typical hearing. Hearing loss continues through childhood and adolescence and typically progresses to profound deafness.

Based on the context provided, here's an informative response to the user's query:

Usher Syndrome Type III: A Rare Genetic Disorder

Usher syndrome type III is a rare genetic disorder characterized by postlingual, progressive hearing loss, variable vestibular dysfunction, and onset of retinitis pigmentosa symptoms. This condition typically affects individuals with normal hearing at birth, but hearing loss begins during late childhood or adolescence.

Key Features:

• Postlingual, progressive hearing loss [1]
• Variable vestibular dysfunction [2]
• Onset of retinitis pigmentosa symptoms, including nyctalopia, constriction of the visual fields, and loss of central visual acuity [1]
• Hearing loss typically begins during late childhood or adolescence [2]

Differential Diagnosis:

Usher syndrome type III can be misdiagnosed as having Usher syndrome types I or II due to its gradual progression of hearing loss. However, it is essential to consider differential diagnoses such as oculo-acoustic syndromes associated with peroxysomal gene alterations (Heimler syndrome with enamel dysplasia) and metabolic disorders.

Treatment:

Hearing aids are often used successfully in individuals with Usher syndrome type III due to the gradual progression of hearing loss. However, there is no cure for this condition, and treatment focuses on managing symptoms and improving quality of life.

References:

• Karjalainen et al., 1985 [1]
• Pakarinen et al., 1995 [1]
• Bolz, HJ (2020) [7]
• Mathur, P (2015) [9]

Note that the citations refer to the numbers assigned to each search result in the context provided.