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GENATLAS PHENOTYPE
last update : 21-06-2016
Symbol ACHM2
Location 2q11.2
Name achromatopsia 2
Corresponding gene CNGA3
related resource Retinal Information Network
Other symbol(s) RMCH2
Main clinical features
  • complete, congenital, total color blindness, photophobia, nystagmus, normal fundi and non recordable phototic electroretinogram, rod monochromatism
  • retinal disorder characterized by lack of color discrimination, reduced visual acuity, nystagmus, and photophobia
  • absent foveal reflex or nonspecific retinal pigment epithelium mottling to mild hypopigmentary changes on fundus examination, atrophic-appearing macular lesion, disruption or loss of the macular inner/outer segments junction of the photoreceptors (PMID:21778272))
    • Genetic determination autosomal recessive
    Related entries . including other cone disorders with incomplete achromatopsia
    Function/system disorder eye
    Type disease
    Mechanism(s)
    Gene mutationChromosome rearrangementEffectComments
    missense   abnormal protein/loss of function impaired cellular trafficking of the cone CNG channel
    Remark(s)
  • four mutations (R227C, R283W, R436W, and F547L) account for approximately 40p100 of all mutant
  • mutations in CNGA3 impair trafficking or function of cone cyclic nucleotide-gated channels
  • the R377W and F488L mutations abolish channel activity while not affecting relative expression levels, and exhibited an enhanced cytosolic aggregation.(Matveev 2010)
  • CNGA3 achromatopsia-associated mutation potentiates the phosphoinositide sensitivity of cone photoreceptor CNG channels by altering intersubunit interactions (PMID: 23552282))
    • Genotype/Phenotype correlations T565M and E593K mutations alter the apparent affinity for cGMP of the channels to cause cone dysfunction, resulting in rod monochromacy