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Macular Corneal Dystrophy (Labrador Retriever Type)

Macular Corneal Dystrophy (MCD) (Labrador Retriever Type) is a hereditary eye disease that causes progressive corneal clouding and vision loss in Labrador Retrievers.

Affected Genes: CHST6

Inheritance: Autosomal Recessive

Variant(canFam6):
chr5:75256890: C>A

Breed: Australian Labradoodle
Lab/Golden Cross
Labradoodle
Labrador Retriever
Service/Assistance Lab/Golden Retriever cross
Service/Assistance Labrador Retriever
UK Breed Council Labrador Retriever

General Information: Macular Corneal Dystrophy (MCD) (Labrador Retriever Type) is an inherited eye disorder that typically affects Labrador Retrievers around 4 to 6 years of age. This condition is characterized by the accumulation of glycosaminoglycans, which leads to clouding of the cornea and the appearance of pinpoint white to gray spots. In some cases, affected dogs may also exhibit the growth of new blood vessels across the corneal surface. These changes gradually impair vision and can lead to significant visual deficits as the disease progresses. Early signs include a noticeable haze in the dog's eyes and reduced clarity, which may lead to further complications if left untreated.

How to Read Your Dog's Test Results for this Genetic Variant:

Two Variants Detected: Dog Likely Affected

One Variant Detected: Dog Unlikely Affected

No Variants Detected: No Effect

Gene / Testing Information: Genetic testing for Macular Corneal Dystrophy (Labrador Retriever Type) focuses on detecting mutations in the CHST6 gene. This disease is inherited in an autosomal recessive manner, meaning that a dog must inherit two copies of the mutated gene (one from each parent) to develop MCD. Carrier dogs, which have only one copy of the mutation, typically do not show symptoms but can pass the gene to their offspring. When two carriers are bred, each puppy has a 25% chance of being affected and a 50% chance of being a carrier. Genetic testing is crucial for responsible breeding practices, allowing breeders to identify carriers and avoid mating them with other carriers. By ensuring that at least one parent in a breeding pair is free from the mutation, breeders can help reduce the risk of producing puppies affected by MCD, thereby promoting healthier litters and maintaining the integrity of the breed.

References:
Tetas Pont R, Downs L, Pettitt L, Busse C, Mellersh CS. A Carbohydrate Sulfotransferase-6 (CHST6) gene mutation is associated with Macular Corneal Dystrophy in Labrador Retrievers. Vet Ophthalmol. 2016 19(6):488-492.