Leukodystrophy in the Standard Schnauzer

Leukodystrophy is a neurodegenerative disease of the dog affecting the central nervous system, specifically the white matter of the brain. The disease is characterized by a severe disorder of the development and maintenance of myelin in the brain.

Clinical signs appear very early, usually shortly after birth or within 4 weeks of the puppy's age. Affected individuals show apathy, abnormal vocalization, hypermetric ataxia (imprecise, exaggerated movements of the limbs), tremors on purposeful movement, head tilt, circling, impaired proprioception (perception of body position), epileptic seizures and ventral strabismus (eyes turning downward). Pathological examination of the brain shows gelatinous consistency of the white matter, mild internal hydrocephalus, marked reduction of myelination and cerebral edema.

The cause of the disease is a missense mutation in the TSEN54 gene (c.371G>A). The mutation is inherited in an autosomal recessive manner. This means that the disease only develops in individuals who inherit the mutated gene from both their parents. Carriers of the mutated gene are clinically healthy, but they pass the mutation to their offspring. In the case of mating two heterozygous individuals, theoretically 25% of the offspring will be clear (without mutation), 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 this disease.

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

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References:

Störk, T., Nessler, J., Anderegg, L., Hünerfauth, E., Schmutz, I., Jagannathan, V., Kyöstilä, K., Lohi, H., Baumgärtner, W., Tipold, A., Leeb, T. : TSEN54 missense variant in Standard Schnauzers with leukodystrophy. PLoS Genet 15:e1008411, 2019. Pubmed reference: 31584937