Spongy encephalopathy

Gene: ASPA

Transmission: Autosomal recessive

For an autosomal recessive genetic disease, an animal must have two copies of the mutation in question to be at risk of developing the disease.  Both parents of an affected animal must be carriers of at least one copy of the mutation.  Animals that have only one copy of the mutation are not at risk of developing the disease but are carrier animals that can pass the mutation on to future generations.

Mutation: Substitution, ASPA gene; c.85 (G>C), p.(A287P), exon 6, chr.E1.

Medical system: Neurological

Breeds: Domestic Cat

Age of onset of symptoms: By 3 – 4 weeks

Spongy encephalopathy was diagnosed in four unrelated Japanese domestic cats, based on clinical symptoms and on pathological findings.  Early onset neurological signs included gait disturbances and head tremors which progressed to an inability to stand (dysstasia), seizures and eventual death by 11 months on average.  A mutation in the ASPA gene was identified that would result in an enzymeopathy : a defective aspartoacytlase enzyme with an inability to metabolize acetylaspartate to acetate and aspartate. Increased levels of acetlyaspartate were detected in the urine of the effected cats.  On necropsy, spongy degeneration involving intracytoplasmic edema within neurons and oligodendrocytes was seen in brain structures including the grey matter of the cerebrum, the brainstem, and the Purkinje layer of the cerebellum.  Mutation frequencies for the ASPA gene within the Japanese domestic cat population are not known.  Spongy encephalopathy in humans is also known as Canavan disease.

References:

OMIA link: [2325-9685]

Takaichi Y, Chambers JK, Shiroma-Kohyama M, et al. (2021) Feline spongy encephalopathy with a mutation in the ASPA gene. Vet Pathol 58:705-712. [pm/33779415]

Contributed by: Alice Asselin et Allie-Sun Turcotte, Class of 2028, Faculty of Veterinary Medicine, University of Montreal. (Translation DWS).