achromatopsia


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ach·ro·ma·top·si·a

, achromatopsy (ă-krō'mă-top'sē-ă, a-krō'mă-top-sē), [MIM*216900, MIM*262300 & MIM*603096]
The complete form of achromatopsia, characterized by severe deficiency of color perception, associated with nystagmus, photophobia, reduced visual acuity, and "day blindness"; is of autosomal recessive inheritance. One form, Achromatopsia type 1, maps to chromosome 14. Achromatopsia type 2 is caused by mutation in the cone photoreceptor cGMP-gated cation channel, alpha-subunit 3 gene (CNGA3) on chromosome 2q. Achromatopsia type 3 is caused by mutation in the CNGB3 on 8q.
[G. a- priv. + chrōma, color, + opsis, vision]

achromatopsia

The formal term for what is popularly termed colour blindness, for a number of clinical syndromes which may be acquired (colour agnosia and cerebral achromatopsia) or inherited (e.g., autosomal recessive), in which the retinal cones and neural fibres conducting the information are intact, but the signal does not process.
 
Clinical findings
Achromatopsia, nystagmus, amblyopia, photophobia, hemeralopia and pupillary irregularities.

Colour blindness/achromatopsia may be
(1) Complete (or total), or
(2) Partial (or incomplete), with a quantitative reduction of one or more attributes of the perception of colour—e.g., brightness, hue, saturation.

Achromatopsia

A generic term which encompasses a number of clinical syndromes which may be acquired—colour agnosia and cerebral achromatopsia—or inherited—autosomal recessive—and in which the retinal cones and neural fibres conducting the information are intact, but the processing of the signals is not.
Clinical findings Achromatopia, nystagmus, amblyopia, photophobia, hemeralopia and pupillary irregularities.

ach·ro·ma·top·si·a

, achromatopsy (ă-krō-mă-top'sē-ă, ă-krō'mă-top-sē)
A severe congenital deficiency in color perception, often associated with nystagmus and reduced visual acuity.
Synonym(s): achromatic vision, monochromatism (2) .
[G. a- priv. + chrōma, color, + opsis, vision]

achromatopsia

A rare but severe defect of colour vision in which the world is perceived almost in monochrome.

Achromatopsia

The inability to distinguish any colors.
Mentioned in: Color Blindness

Achromatopsia 

Total colour blindness. The majority of cases are autosomal recessively inherited and caused by a mutation in genes CNGA3, CNGB3 and CNAT2. There are two types of achromatopsia. Complete achromatopsia which results from having only rods and no functional cones (rod monochromat) have photophobia, poor acuity and nystagmus. Incomplete achromatopsia in which there are the same symptoms, but in a diminished form. Patients benefit from dark tinted lenses. Achromatopsia is non-progressive and very rare: one person in about 35 000 people. A few cases may be acquired resulting from a lesion in cortical area V4 (central achromatopsia). Syn. achromasia; achromatic vision; achromatism; acritochromacy; monochromatism. See defective colour vision; hemiachromatopsia; monochromat.

ach·ro·ma·top·si·a

, achromatopsy (ă-krō-mă-top'sē-ă, ă-krō'mă-top-sē) [MIM*216900, 262300 & 603096]
A severe congenital deficiency in color perception, often associated with nystagmus and reduced visual acuity.
Synonym(s): monochromatism (2) .
[G. a- priv. + chrōma, color, + opsis, vision]
References in periodicals archive ?
A type of achromatopsia previously identified as ACHM1 was later found to be the same as ACHM3 caused by cyclic nucleotide-gated channel beta-3 (CNGB3) gene (MIM 605080).8 Among other genes are included cyclic nucleotide-gated channel alpha-3 (CNGA3; MIM 600053) causing ACHM29, Guanine nucleotide-binding protein G subunit [alpha]-2 (GNAT2; MIM 139340) causing ACHM4, 10 phosphodiesterase 6C (PDE6C; MIM 613093) causing ACHM5, 11 cone inhibitory phosphodiesterase 6H (PDE6H; MIM 601190) causing ACHM612 and activating transcription factor 6 (ATF6; MIM 605537) causing ACHM7.13 The current study was planned to report two Pakistani families that were initially evaluated as having nystagmus phenotype.
* The report assesses Achromatopsia therapeutics based on drug target, mechanism of action (MoA), route of administration (RoA) and molecule type
Achromatopsia is a chronically debilitating inherited eye disorder that severely limits a person's sight.
The company had earlier initiated a Phase I/II clinical trial of its gene therapy product for the treatment of achromatopsia caused by mutations in the CNGB3 gene.
In our opinion, simple illusions like macropsia or micropsia, metamorphopsia, illumination, colour or clarity, dysmorphopsia, plagiopsia, and achromatopsia may be explained by the loss of balance of this longitudinal temporooccipital network.
Speaking to the Daily Post last night, she said: "I knew the signs of achromatopsia because two of my nephews already had it, and like Cameron, their problems began with nystagmus - an involuntary movement of the eyes.
(25) In most cases, colour perception is not completely abolished; hence the term dyschromatopsia is used to distinguish from the much rarer situation of cerebral achromatopsia. (26) Due to the close proximity of regions within the brain, patients with cerebral dyschromatopsia present comorbid with prosopagnosia in 72% of cases.
The alpha subunit of transducin is encoded by GNAT2 [23], and evidence shows that GNAT2 is involved in diseases such as achromatopsia [24] and oligocone trichromacy [25].
M2 PHARMA-October 20, 2016-AGTC files IND with US FDA for gene therapy product for treating achromatopsia
In conjunction, AGTC has a been granted orphan drug designation from the EC and the US Food and Drug Administration (FDA) for its gene therapy product candidates for the treatment of X-linked retinoschisis and for the treatment of achromatopsia caused by mutations in the CNGA3 and CNGB3 genes.
Diagnosed with achromatopsia at eight weeks old, the rare genetic condition means she is registered blind.
The schoolgirl from Kinmel Bay suffers from achromatopsia, a rare genetic condition that leaves her completely colourblind.