Achromatopsia 2

Last update 08 May 2025

Basic Info

Synonyms

ACHM2, ACHROMATOPSIA 2, Achromatopsia 2

+ [10]

Introduction

An autosomal recessive condition caused by mutation(s) in the CNGA3 gene, encoding cyclic nucleotide-gated cation channel subunit alpha-3. It is characterized by achromatopsia.

Clinical Trials associated with Achromatopsia 2

NCT01927536

/ CompletedNot ApplicableIIT

Evaluating Color Perception Under LED Red/Green and Green Dominant Light

The investigators are testing a Light-emitting Diode (LED) flashlight from First-Light™ USA called the Tomahawk MC Tactical Light to determine the range of colors people are able to see with these flashlights at night. The flashlight has been designed to reduce visibility of the user and uses a combination of green and red LED lamps to achieve this. In this study investigators wish to determine how well a subject can differentiate colors at night in a quantifiable manner. Investigators will use the Farnsworth Munsell 100 hue test which requires the user to put shades of red, green, blue and yellow into progressive color order which is scored according to the manufactures specifications.

Start Date23 Apr 2013

Sponsor / Collaborator

University of Colorado Denver

100 Clinical Results associated with Achromatopsia 2

100 Translational Medicine associated with Achromatopsia 2

0 Patents (Medical) associated with Achromatopsia 2

Literatures (Medical) associated with Achromatopsia 2

05 Feb 2025·Translational Vision Science & Technology

Visual Tract Integrity Before and After Gene Therapy in Congenital Achromatopsia

Article

Author: Levin, Netta ; Guy, Nitzan ; Abramovitch, Hillel ; Banin, Eyal ; Bick, Atira S. ; Mckyton, Ayelet ; Elul, Deena

PurposeCNGA3 achromatopsia is a rare hereditary syndrome caused by dysfunction of cone photoreceptors. Visual information is therefore obtained only by rod photoreceptors, resulting in low acuity, photoaversion, and color blindness. Trials using gene therapy have been initiated recently, in which clinical improvement was subtle.MethodsTo explain this suboptimal outcome, we used diffusion tensor imaging to assess visual pathway integrity in 3 CNGA3 achromatopsia patients before and after gene therapy, and compared them with 16 normally sighted adults.ResultsNo significant differences from normal subjects in optic tract and radiation were detected. Fiber integrity reduction was observed in the occipitocallosal fibers. These differences showed some normalization after treatment, but intersubject variability was evident. Specifically, the observed changes were related to radial diffusivities, reflecting fiber myelination or glial cell alterations.ConclusionsDespite the fundamental role of cone photoreceptors in human sight, primary visual pathways in patients are comparable with those of healthy individuals and thereby fiber integrity is probably not an obstacle for recovery. Preliminary results suggest that the splenial fibers are less cohesive in naïve patients and regain some integrity after treatment. These findings add to previous reports on this rare population and suggest that novel information is processed within the visual cortex after treatment.Translational RelevancePatients with complete color blindness were treated using a novel gene augmentation therapy. Unfortunately, the patients did not experience a sudden eureka moment of being able to perceive the full spectrum of colors. In this study, we rule out fiber disintegration as the cause of their limited recovery.

01 Jan 2022·Molecular Diagnosis & TherapyQ4 · MEDICINE

Achromatopsia: Genetics and Gene Therapy

Q4 · MEDICINE

Review

Author: Priglinger, Siegfried ; Michalakis, Stylianos ; Priglinger, Claudia ; Gerhardt, Maximilian ; Rudolph, Günther

Achromatopsia (ACHM), also known as rod monochromatism or total color blindness, is an autosomal recessively inherited retinal disorder that affects the cones of the retina, the type of photoreceptors responsible for high-acuity daylight vision. ACHM is caused by pathogenic variants in one of six cone photoreceptor-expressed genes. These mutations result in a functional loss and a slow progressive degeneration of cone photoreceptors. The loss of cone photoreceptor function manifests at birth or early in childhood and results in decreased visual acuity, lack of color discrimination, abnormal intolerance to light (photophobia), and rapid involuntary eye movement (nystagmus). Up to 90% of patients with ACHM carry mutations in CNGA3 or CNGB3, which are the genes encoding the alpha and beta subunits of the cone cyclic nucleotide-gated (CNG) channel, respectively. No authorized therapy for ACHM exists, but research activities have intensified over the past decade and have led to several preclinical gene therapy studies that have shown functional and morphological improvements in animal models of ACHM. These encouraging preclinical data helped advance multiple gene therapy programs for CNGA3- and CNGB3-linked ACHM into the clinical phase. Here, we provide an overview of the genetic and molecular basis of ACHM, summarize the gene therapy-related research activities, and provide an outlook for their clinical application.

04 Jul 2019·Neuro-Ophthalmology

Comparison of a Smartphone Application with Ishihara Pseudoisochromatic Plate for Testing Colour Vision

Article

Author: Ighani, Mehrnaz ; Eghrari, Allen O. ; Fliotsos, Michael Joseph ; Zhao, Jiawei

The Eye Handbook (EHB) is the most frequently downloaded smartphone application with diagnostic tools for eye-care providers. However, limited data exists validating the EHB test to gold standard colour vision testing. EHB and Ishihara colour vision tests were evaluated and compared under simulated colour vision loss through use of image processing software. Images of both tests were processed through ImageJ to 32 bit-grey scale and blue channel under split RBG channel to model total colour vision loss and red-green (R-G) deficiency, respectively. Two colour plates differentiated R-G deficiency from total colour blindness in EHB compared with eight Ishihara plates. Without colour information, correct numerals were identified in 3.5/15 EHB plates converted to 32-bit greyscale, versus 1/16 in Ishihara. We conclude EHB may underestimate colour vision loss severity in persons with normal contrast sensitivity compared to Ishihara. Eye-care providers need to be aware of the potential inconsistency compared to standardised methods, including limitations in differentiating patients with R-G colour deficiencies from total colour blindness.

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Achromatopsia 2

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