This study is aimed to characterize Russian population of Usher patients.

This study is aimed to characterize Russian population of Usher patients.

Tasks:

Stage 1. Formation of the primary cohort of patients. Patients pre-recruiting will be performed based on Deaf-Blind Support Foundation "Con-nection" patient database analysis. Patients with clinically confirmed Usher syndrome will be evaluated according to available data of the clinical examination.

Stage 2. Clinical examination of patients.

Each patient will undergo the following diagnostic procedures according to the unified protocol:

• Visometry (with correction and without correction)
• Ophthalmoscopy
• Perimetry
• Optical coherence tomography
• Electroretinography
• Visually evoked potentials
• Refractometry
• Pneumotonometry
• Biomicroscopy
• Tonal audiometry
• Electronic audiometry (ASSR test)
• Acoustic impedance measurement
• Vestibulometry
• Electronystagmography
• Any additional examinations and consultations if necessary

Medical record will be developed and maintained for each patient consisting results of extended clinical examination.

Stage 3. Genetic study of patients. All enrolled patients will undergo single 4 ml peripheral venous blood sampling. DNA will be extracted from leucocytes. DNA samples will be analyzed and placed for long-term storage in liquid nitrogen. Statistical and bioinformatic analysis of detected genetic mutations in the study cohort will be performed.

Inclusion Criteria:

• Patient fulfill the clinical characteristics for Usher syndrome type I, II or III as defined by the Usher syndrome consortium
• According to the results of audiometry, hearing loss is moderate or severe (level of acoustic threshold of audibility is 41 decibel and higher).
• Results of perimetry for each eye show narrowing for 15 degrees or more.
• Patient is familiar with Participant information sheet
• Patient signed informed consent form

Non-inclusion Criteria:

• Participation in other clinical trials (or administration of investigational drugs) during 3 months prior inclusion
• Any conditions limiting compliance (dementia, neuropsychiatric disease, drug and alcohol abuse etc.)
• Medical history of traumatic injury of eyes, barotrauma, concussion, craniocerebral trauma, cerebrovascular accident

Exclusion Criteria:

• Patient's refusal from the further participation in the trial
• Decompensated diabetes mellitus
• Severe coronary artery disease
• Chronic infectious disease
• Patients with malignant tumors including postoperative period, patients receiving chemotherapy and/or radiotherapy

It is assumed that at least 28 patients of the Russian population of men and women aged 18 to 65 years, with verified diagnosis of Usher syndrome (type I, II or III as defined by the Usher syndrome consortium), will take part in this research study.