Clinical and Genetic Characterization of Individuals With Achromatopsia

Study Overview
=================
Brief Summary
-----------------
The purpose of this study is to identify individuals with achromatopsia caused by mutations in the CNGB3 gene and characterize their clinical condition using several tests of visual function every 6 months for up to 1.5 years.

Detailed Description
-----------------
Individuals with a clinical diagnosis of achromatopsia will be asked to provide informed consent and will then have a single 5 mL blood sample drawn for DNA sequence analysis of genes known to cause achromatopsia, including the CNGB3 gene. All participants will be informed of the results of testing for these mutations. Those with mutations in both alleles of the CNGB3 gene will be evaluated every 6 months for up to 1.5 years by using a variety of non-invasive visual function tests to more fully characterize their clinical condition. This testing will include routine ophthalmic examination and tests of visual acuity, color vision, reading speed, perimetry, nystagmus, light sensitivity, optical coherence tomography, adaptive optics retinal imaging, electroretinography, fundus photography and completion of a quality of life questionnaire.

Official Title
-----------------
Clinical and Genetic Characterization of Individuals With Achromatopsia

Conditions
-----------------
Achromatopsia

Participation Criteria
=================
Eligibility Criteria
-----------------
Inclusion Criteria: Clinical diagnosis of achromatopsia (screening portion of study); Molecular confirmation of mutations in the CNGB3 gene (main portion of study); At least 6 years of age; Willing and able to perform study procedures; Signed informed consent(s) obtained (and child assent where applicable). Exclusion Criteria: Not able to have a blood sample drawn; Pre-existing eye conditions that would interfere with interpretation of study endpoints (e.g. glaucoma, corneal or lenticular opacities, diabetic retinopathy, history of retinal detachment); Participating in an interventional research study of drugs or devices for treatment of achromatopsia or other retinal diseases; Use of medications that may impair color vision (e.g. hydroxychloroquine); Any condition which leads the investigator to believe that the participant cannot comply with the protocol requirements or that may place the participant at an unacceptable risk for participation.

Ages Eligible for Study
-----------------
Minimum Age: 6 Years

Sexes Eligible for Study
-----------------
All

Accepts Healthy Volunteers
-----------------
No

Study Plan
=================
How is the study designed?
-----------------
What is the study measuring?
-----------------
Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Visual acuity | Visual acuity will be measured by EVA or ETDRS methods | Annually for up to 1.5 years | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Color Vision | Color vision will be measured by Farnsworth D-15 test and anomaloscope | annually for up to 1.5 years | 
| Adaptive Optics Retinal Imaging | Adaptive optics retinal imaging will be performed using the method of Genead et al. (Invest Ophthalmol Vis Sci 2011;52:7298-308). | annually for up to 1.5 years | 

 Terms related to the study
=================
Keywords Provided by Centre Hospitalier Valida
-----------------
achromatopsia, CNGB3