Spinocerebellar Ataxia with Myokymia and Seizures

Ataxia is characterized by uncoordinated movements and represents a relatively nonspecific clinical sign. Spinocerebellar ataxia with myokymia and seizures is caused by alterations in the KCNJ10 gene.

Symptoms

Affected dogs usually begin to show clinical signs between the ages of 2 and 10 months. Typical initial signs include myokymia, which is a term that describes rapid, involuntary muscle contractions that can make the dog's skin appear to be "making waves." Hearing loss and seizures may also occur.

Disease Management

There is currently no cure for spinocerebellar ataxia with myokymia and seizures. Treatment usually focuses on symptom management and may include medications to control seizures.

Genetic basis

This disease follows an autosomal recessive mode of inheritance. Autosomal recessive inheritance means that the dog, regardless of sex, must receive two copies of the mutation or pathogenic variant to be at risk of developing the disease. Both parents of an affected dog must carry at least one copy of the mutation. Animals with only one copy of the mutation are not at increased risk of developing the disease, but may pass the mutation on to future generations. Breeding between dogs carrying genetic variants that can cause disease, even if they do not show symptoms, is not recommended.

Technical report

This disease is caused by a mutation in the KCNJ10 gene, which encodes a potassium channel protein. Gilliam et al. found that the mutation in KCNJ10 associated with spinocerebellar ataxia with myokymia and seizures in Parson Russell Terriers and Jack Russell Terriers is c.627C>G. The researchers suggested in their study that the c.627C>G variant, which is the one we analyzed in our test, could affect potassium ion trafficking and membrane depolarization of neurons.

Most affected breeds

Belgian Shepherd
Jack Russell Terrier
Malinois
Parson Russell Terrier
Russell Terrier
Smooth-Haired Fox Terrier

Bibliography

Gilliam D, O'Brien DP, Coates JR,et al. A homozygous KCNJ10 mutation in Jack Russell Terriers and related breeds with spinocerebellar ataxia with myokymia, seizures, or both. J Vet Intern Med. 2014 May-Jun;28(3):871-7.