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Juvenile Myoclonic Epilepsy (Rhodesian Ridgeback Type)

Juvenile myoclonic epilepsy (Rhodesian ridgeback type) is an inherited neurological disorder in dogs that causes frequent, uncontrolled muscle movements, known as myoclonic jerks, typically occurring between 6 weeks and 1.5 years of age, and can progress to generalized seizures.




Affected Genes: DIRAS1

Inheritance: Autosomal Recessive

Variant(canFam6):
chr20:56270904-56270907: 4 bp deletion AGAC

Breed: Rhodesian Ridgeback

General Information: Juvenile myoclonic epilepsy (Rhodesian ridgeback type) is a neurological disorder in dogs that manifests between 6 weeks and 1.5 years of age with frequent, uncontrolled muscle movements known as myoclonic jerks. These jerks, which may resemble electric shocks, typically occur in the limbs, head, eyelids, and jaw, ranging from mild to severe. They are most common when dogs are relaxed or in the early stages of sleep and can increase after vaccinations or exposure to certain stimuli. Affected dogs generally appear normal between episodes but may be disoriented or agitated immediately afterward. In some cases, the disease can progress to generalized seizures.

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 of the DIRAS1 gene can identify carriers of juvenile myoclonic epilepsy (Rhodesian ridgeback type), an autosomal recessive disorder requiring two copies of the mutated gene for the disease to develop. Carrier dogs typically do not show symptoms but breeding two carriers together can produce affected pups, with a 25% chance of inheriting the disease and a 50% chance of being a carrier. Reliable genetic testing is crucial for informed breeding decisions to prevent affected litters. To eliminate the mutation from breeding lines, it is recommended not to breed known carriers together. Dogs without the mutation do not have an increased risk of producing affected pups.

References:
Wielaender F, Sarviaho R, James F, Hytonen MK, Cortez MA, Kluger G, Koskinen LLE, Arumilli M, Kornberg M, Bathen-Noethan A, Tipold A, Rentmeister K, Bhatti SFM, Hulsmeyer V, Boettcher IC, Tastensen C, Flegel T, Dietschi E, Leeb T, Matiasek K, Fischer A, Lohi H. Generalized myoclonic epilepsy with photosensitivity in juvenile dogs caused by a defective DIRAS family GTPase 1. Proc Natl Acad Sci USA. 2017 114(10):2669-2674.