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Mutational spectrum in Usher syndrome type II
X M Ouyang1, D Yan, J F Hejtmancik
1Department of Otolaryngology, University of Miami, Miami, FL 33136, USA.
Clinical Genetics
|March 18, 2004
Summary
The USH2A gene mutation screening in Usher syndrome type II identified the 2299delG mutation as the most common cause. This study found USH2A mutations in 35% of patients with this genetic disorder.
Area of Science:
- Genetics
- Ophthalmology
- Audiology
Background:
- Usher syndrome type II is an inherited disorder causing hearing loss and retinitis pigmentosa (RP).
- The USH2A gene is a primary genetic cause of Usher syndrome type II.
- Understanding USH2A mutation frequency is crucial for genetic diagnosis and counseling.
Purpose of the Study:
- To determine the frequency and spectrum of USH2A gene mutations in patients with Usher syndrome type II.
- To identify the most prevalent mutations within the USH2A gene.
- To characterize novel mutations and polymorphisms in the USH2A gene.
Main Methods:
- Mutation screening of the USH2A gene in 88 probands diagnosed with Usher syndrome type II.
- Identification and characterization of pathogenic mutations and polymorphisms.
- Genotyping to determine homozygous and compound heterozygous states.
Main Results:
- USH2A mutations were identified in 35% (31/88) of the probands.
- The 2299delG mutation was the most frequent, accounting for 16.5% of alleles and 77.5% of pathogenic alleles.
- Six distinct mutations and eight polymorphisms (five novel) were identified, including a new missense mutation (N357T).
Conclusions:
- USH2A mutations are a significant cause of Usher syndrome type II.
- The 2299delG mutation is the predominant mutation in the USH2A gene for this condition.
- Further genetic studies are warranted to fully elucidate the role of USH2A in Usher syndrome type II.