Ataxia in Norwegian Elkhound

Ataxia is described as a disorder of coordination of voluntary movements and represents a relatively non-specific clinical symptom. Abnormal gait, particularly of the pelvic limbs, is evident in puppies as young as 4 weeks of age. The puppies are insecure, the movement of the pelvic limbs is slippery or poorly measured, they often fall and have a hanging tail atypical for the breed. Axonal swellings and spheroids in the granular layer of the cerebellum have been found in the Purkinje cell axons.

In the Norwegian Elkhound, this condition is caused by the c.1001del mutation in the HACE1 gene, which results in a frameshift frame and a premature inclusion of a stop codon.

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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References:

Bellamy, K.K.L., Skedsmo, F.S., Hultman, J., Arnet, E.F., Guttersrud, O.A., Skogmo, H.K., Thoresen, S.I., Espenes, A., Jäderlund, K.H., Lingaas, F. : A 1 bp deletion in HACE1 causes ataxia in Norwegian elkhound, black. PLoS One 17:e0261845, 2022. Pubmed reference: 35061740