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Spongy Degeneration with Cerebellar Ataxia (KCNJ10 gene, Belgian Malinois)

Spongy Degeneration with Cerebellar Ataxia (KCNJ10 gene, Belgian Malinois)

Cancellous degeneration with cerebellar ataxia is a severe neurodegenerative disease characterized by problems coordinating movement and balance, seizures and myokymia.

Symptoms

Cancellous degeneration with cerebellar ataxia in Malinois dogs is characterized by an early onset of the disease, usually between 4 and 7 weeks of age. Affected dogs present with severe ataxia, with difficulty coordinating movements and maintaining balance, resulting in frequent falls. They may also experience shivering and are unable to walk without falling. In severe cases, the condition can be debilitating and require euthanasia at an early age. Other symptoms include seizures, myokymia, neuromyotonia and hearing changes.

Disease Management

There is no treatment that cures spongiform degeneration with cerebellar ataxia, the goal of disease management is to provide supportive care to improve the dog's quality of life. Antiepileptic drugs may be used to reduce 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

Cancellous degeneration with cerebellar ataxia is a neurodegenerative disorder described in Belgian Malinois dogs and related to the KCNJ10 gene. This gene encodes a potassium channel that is expressed in the central nervous system, eye, inner ear and kidney. In the brain, expression predominates in the cerebral and cerebellar cortex, caudate nucleus and putamen. KCNJ10 channels are involved in the regulation of extracellular potassium. A nonsense mutation (c.986T>C) has been identified in the Belgian Malinois breed that has been associated as a possible cause of the described disease. However, it is important to note that this variant explains only a part of the clinical cases studied. Furthermore, due to the heterogeneity of cerebellar dysfunction, further research is required to understand the specific phenotype and the variants responsible in its entirety.

Most affected breeds

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

Bibliography

Mauri N, Kleiter M, Leschnik M,et al. A Missense Variant in KCNJ10 in Belgian Shepherd Dogs Affected by Spongy Degeneration with Cerebellar Ataxia (SDCA1). G3 (Bethesda). 2017 Feb 9;7(2):663-669.

Van Poucke M, Stee K, Bhatti SF,et al. The novel homozygous KCNJ10 c.986T>C (p.(Leu329Pro)) variant is pathogenic for the SeSAME/EAST homologue in Malinois dogs. Eur J Hum Genet. 2017 Feb;25(2):222-226.