Achromatopsy 2 (ACHM2 Labrador)

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

• Achromatopsia (ACHM2) is caused by a regression of the cone cells responsible for colour vision.
• Affected puppies show day blindness.
• The first symptoms appear after 8-12 weeks.
• The condition remains the same throughout life, but is usually not detected during eye examinations.

This mutation test detects a deletion of 3 base pairs in exon 7 of the CNGA3 gene.

Inheritance: autosomal recessive.

→ The hereditary disease only occurs if 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.

Genotypes:

N/N = genetically normal

The dog has no predisposition for ACHM2 and therefore cannot pass it on to its offspring.

N/achm2 = a 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 is passed on 100% to the offspring. The offspring are carriers or affected.

• 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.

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

Further information is available at: Online Mendelian Inheritance in Animals verfügbar