Genetic basis of Dandy Walker Like Malformation in Eurasier dogs - is caused by a single base deletion mutation (c.1713delC) in the VLDLR gene (very low density lipoprotein receptor gene). This mutation leads to a frameshift and premature stop codon (p.W572Gfs*10), predicted to produce a non-functional truncated VLDLR protein. The inheritance is autosomal recessive; affected dogs have two copies of the mutant gene while carriers have one copy without clinical signs. The VLDLR gene plays an essential role in the reelin signaling pathway important in brain development.
Pathophysiology - The VLDLR protein is crucial for normal cerebellar development; loss of function leads to cerebellar hypoplasia primarily affecting the cerebellar vermis. This hypoplasia results in improper formation of the brain region controlling coordination and balance. The defect causes non-progressive cerebellar ataxia, with affected dogs showing neurological dysfunction from puppyhood.
Complications - Clinical symptoms typically appear from 5 to 6 weeks of age, when puppies start to walk. Signs include tremors, generalized cerebellar ataxia (uncoordinated movements), high-stepping gait, abnormal eye movements (nystagmus), and leaning or rolling to one side. Some affected dogs may develop hydrocephalus and epileptic seizures. The disease is usually non-progressive, and although motor coordination is impaired, intellectual function remains normal. Severity varies between individuals, ranging from mild balance difficulties to severe ataxia with frequent falling.
Why This Matters to Breeders and Vets - Eurasier is a relatively young breed with a small founder population, increasing the risk of recessive inherited diseases like DWLM. Genetic testing is available to identify carriers and avoid breeding two carriers, which would produce affected puppies. Vets need awareness of this condition for timely diagnosis and supportive care for affected dogs.