Genetic basis - Gangliosidosis (GM1 type) in Portuguese Water Dogs is caused by a recessive mutation in the GLB1 gene, specifically a substitution mutation c.179G>A (R60H) that affects the production of the lysosomal enzyme beta-galactosidase. This enzyme deficiency causes abnormal accumulation of GM1 gangliosides in cells, particularly affecting the central and peripheral nervous systems. The disorder is inherited in an autosomal recessive manner: affected dogs have two copies of the mutation, carriers have one, and clear dogs have none
Pathophysiology - The lack of functional beta-galactosidase leads to the lysosomal storage of GM1 gangliosides, causing toxicity and progressive cell damage, especially in nerve cells. This accumulation disrupts normal neurological function and leads to symptoms such as loss of coordination, vision impairment, muscle tremors, and neurological degeneration. Progressive loss of neurons and demyelination are observed in the brain and spinal cord, leading to severe decline and death
Complications - Progressive neurological deterioration with ataxia and tremors. Vision problems progressing to blindness. Weight loss and muscle wasting. Behavioral changes. The disease is progressive, leading to premature death or euthanasia typically before 1 year of age due to poor quality of life.
Why This Matters to Breeders and Vets - Gangliosidosis GM1 severely impacts the health and welfare of Portuguese Water Dogs. For breeders, genetic testing is crucial to avoid producing affected dogs and to improve breed health. For veterinarians, understanding this fatal lysosomal storage disease aids in early diagnosis and management, as well as educating owners and breeders on the genetic basis and importance of preventing the condition through responsible breeding
