Novel mutations in MYO7A and USH2A in Usher syndrome

Area of Science:

• Genetics and Molecular Biology
• Ophthalmology
• Audiology

Background:

• Usher syndrome is an autosomal recessive disorder characterized by retinitis pigmentosa and neurosensory deafness.
• Three clinical types (USH1, USH2, USH3) and 11 mutated genes are known.
• MYO7A and USH2A mutations account for a significant proportion of Usher syndrome type 1 and type 2 cases, respectively.

Purpose of the Study:

• To screen for mutations in the MYO7A gene in patients with Usher syndrome type 1.
• To screen for mutations in the USH2A gene in patients with Usher syndrome type 2.
• To identify novel mutations contributing to Usher syndrome.

Main Methods:

• Single-strand conformation polymorphism (SSCP) screening was employed.
• MYO7A was screened in 12 unrelated patients with Usher syndrome type 1.
• USH2A was screened in 28 unrelated patients with Usher syndrome type 2.

Main Results:

• Six mutations in MYO7A were identified in five Usher syndrome type 1 patients, including two novel mutations (c.397C > G and 1244-2A > G).
• These MYO7A mutations accounted for 42% of the studied USH1 cohort.
• Twelve mutations in USH2A were found in 11 Usher syndrome type 2 patients, including four novel mutations (c.850delGA, c.1841-2A > G, c.3129insT, and c.3920C > G).
• These USH2A mutations accounted for 39% of the studied USH2 cohort.

Conclusions:

• The study identified novel mutations in MYO7A and USH2A, expanding the spectrum of known genetic causes for Usher syndrome.
• The findings confirm the significant role of MYO7A and USH2A in Usher syndrome types 1 and 2.
• This genetic information is crucial for accurate diagnosis and potential genetic counseling for Usher syndrome patients.