Skip to main content
« Back to the lexicon overview

Achromatopsia 2 (ACHM2 German Shepherd Dog)

Achromatopsia develops as a result of degeneration of the cone cells responsible for color vision. The symptoms are day blindness and impaired vision. The causative mutation for achromatopsia 2 is found in German Shepherds. It is autosomal recessive.


  • Severely impaired vision in bright daylight.
  • Avoids bright light
  • Vision is unimpaired in normal to dim light conditions

Allgemeine Information

  • Affected puppies show day blindness with the first symptoms appearing after 8-12 weeks.
  • The condition remains the same throughout life, but is usually not detected during eye examinations.

Affected breeds

German Shepherd Dog

Genotype and Lab Report

Inheritance: autosomal recessive

The disease only occurs when both alleles of the gene are affected by the mutation (achm2/achm2). Dogs that have only one allele with the causative mutation (N/achm2) are clinically healthy carriers.


N/N = genetically normal

The dog has no variants for ACHM2 and thus cannot pass it on to offspring.

N/achm2 = carrier

The dog is a clinically healthy carrier. The variation is passed on 50% to the offspring, which are also carriers.

achm2/achm2 = affected

The variation will be passed on to 100% to the offspring.


  • Carrier animals can be bred to normal animals (N/achm2 x N/N). Before using the offspring in breeding, it should be tested whether they are normal or carriers.
  • Mating two carrier animals (N/achm2 x N/achm2) should be avoided because there is a 25% chance that the offspring will be affected.
  • Affected animals (achm2/achm2) should be excluded from breeding.

Test Information

This mutation test detects the c.C1270T mutation in the CNGA3 gene.



Tanaka, N., Dutrow, E.V., Miyadera, K., Delemotte, L., MacDermaid, C.M., Reinstein, S.L., Crumley, W.R., Dixon, C.J., Casal, M.L., Klein, M.L., Aguirre, G.D., Tanaka, J.C., Guziewicz, K.E.: Canine CNGA3 Gene Mutations Provide Novel Insights into Human Achromatopsia-Associated Channelopathies and Treatment. PLoS One 10:e0138943, 2015. Pubmed reference: 26407004. DOI: 10.1371/journal.pone.0138943


More Information can be found on the website: Online Mendelian Inheritance in Animals.

« Back to the lexicon overview