Juvenile Brain Disease ( JBD ) / Juvenile Encephalopathy  in Jack Russell Terrier and Parson Russell Terrier

Juvenile encephalopathy (JBD) is a severe brain disease characterized by the early onset (usually in puppies between 6 and 12 weeks of age) of progressively worsening epileptic seizures. The condition is accompanied by mitochondrial dysfunction and neurodegeneration causing ataxia and irreversible brain damage.

The disease is caused by a 6-bp deletion of the PITRM1 gene, encoding for a mitochondrial protease important for mitochondrial function. The mutation (c.175_180del) results in the loss of two amino acid residues in the N-terminal part of PITRM1.

The mode of inheritance of the mutation is autosomal recessive. This means that only individuals who inherit the mutated gene from both parents will develop the disease. Carriers of the mutated gene are clinically healthy but pass the mutation on to their offspring. In the case of a mating between two heterozygous individuals, theoretically 25% of the offspring will be completely healthy, 50% of the offspring will be carriers and 25% of the offspring will inherit the mutated gene from both parents and will therefore be affected by the disease.

The genetic test can clearly reveal the genotype of the animal and is a useful tool for breeders to prevent unintentional breeding of affected puppies.

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Reference:

Hytönen, M.K., Sarviaho, R., Jackson, C.B., Syrjä, P., Jokinen, T., Matiasek, K., Rosati, M., Dallabona, C., Baruffini, E., Quintero, I., Arumilli, M., Monteuuis, G., Donner, J., Anttila, M., Suomalainen, A., Bindoff, L.A., Lohi, H. : In-frame deletion in canine PITRM1 is associated with a severe early-onset epilepsy, mitochondrial dysfunction and neurodegeneration. Hum Genet 140:1593-1609, 2021. Pubmed reference: 33835239