Congenital Mirror Movement Disorder (CMM1) in Weimaraners

Congenital mirror movement disorder is a rare inherited neurological disorder that has been described in Weimaraners. In healthy dogs, the brain controls the movement of the right and left sides of the body separately. In dogs with CMM1, this control does not work properly, resulting in simultaneous, synchronous movement of the limbs instead of the normal alternating step. The disease appears in puppies and is typically manifested by an abnormal gait resembling a rabbit hopping, synchronous movement of the hind and front limbs, unsteadiness in movement, weakness of the limbs, difficulty getting up, and frequent stumbling.

The cause of the disease is the mutation c.643_644dup in the EFNB3 gene, which plays an important role in the development of the nervous system and the correct control of movements.

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 of their parents. Carriers of the mutated gene are of normal height, but they pass the mutation on to their offspring. In the case of mating two heterozygous individuals, theoretically 25% of the offspring will be so-called pure (without the 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 the unintentional reproduction of affected puppies.

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References:

Schwarz, C., Bartenschlager, F., Kershaw, O., Braun, J., Guevar, J., Jagannathan, V., Epplen, J.T., Reineking, W., Baumgärtner, W., Bhatia, K.P., Gruber, A.D., Leeb, T. : EFNB3 frameshift variant in Weimaraner dogs with a condition resembling a congenital mirror movement disorder. Mov Disord 40:1883-1891, 2025. Pubmed reference: 40401490