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Achromatopsia type 2 in German Shepherds        ACHM2-GS Test      Code 201

For breeds: German Shepherd

A collaborative research effort by a team of investigators at the University of Pennsylvania, veterinary ophthalmologist Dr. Chris Dixon and the OptiGen Research Program, has lead to the discovery of a novel mutation in the CNGA3 gene that causes Day Blindness in German Shepherd (1). This condition, also known as Achromatopsia, or color blindness, is characterized by cone photoreceptor dysfunction, severely reduced visual acuity or complete vision loss during daylight hours, and photophobia. The disease is present at birth (i.e. it is congenital) and is manifested clinically when dogs are approximately 8-10 weeks of age.

The mutation identified in the German Shepherd breed is analogous to the mutation in the CNGA3 gene that causes Achromatopsia type 2 (ACHM2) disease with similar clinical representation in humans. So far this particular mutation has not been observed in dog breeds besides the German Shepherd, and OptiGen currently offers the ACHM2-GS test only for this breed.

Note: A different mutation in the same CNGA3 gene causes a similar form of day blindness/Achromatopsia in Labrador Retrievers (1). OptiGen offers the ACHM2-LR test for Achromatopsia in Labrador Retrievers.

Testing/Breeding strategies:

ACHM2 in the German Shepherd is inherited as an autosomal recessive trait, meaning that two copies of the mutation are required in order for the ACHM2 disease to occur.

In order to avoid producing ACHM2 affected offspring, at least one parent of any litter should be DNA tested and shown to be Normal/Clear of the CNGA3 mutation.

 

Expected results for breeding strategies using the
mutation test for ACHM2-GS
Parent 1
Genotype
Parent 2 Genotype
Normal/ClearCarrierAffected
Normal/ClearAll = Normal/Clear1/2 = Normal/Clear
1/2 = Carrier
All = Carrier
Carrier1/2 = Normal
1/2 = Carrier
1/4 = Normal/Clear
1/2 = Carrier
1/4 = Affected
1/2 = Carrier
1/2 = Affected
Affected All = Carrier
1/2 = Carrier
1/2 = Affected

All = Affected

 

References:

1.Tanaka N, Dutrow EV, Miyadera K, Delemotte L, MacDermaid CM, Reinstein SL, et al. (2015) Canine CNGA3 Gene Mutations Provide Novel Insights into Human Achromatopsia - Associated Channelopathies and Treatment. PLoS ONE 10(9): e0138943

 

 


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