GM1 gangliosidosis in a Japanese domestic cat: a new variant identified in Hokkaido,Japan

A male Japanese domestic cat with retarded growth in Hokkaido, Japan, showedprogressive motor dysfunction, such as ataxia starting at 3 months of age and tremors,visual disorder and seizure after 4 months of age. Finally, the cat died of neurologicaldeterioration at 9 months of age. Approximately half of the peripheral blood lymphocyteshad multiple abnormal vacuoles. Magnetic resonance imaging showed bisymmetricalhyperintensity in the white matter of the parietal and occipital lobes in the forebrain onT2-weighted and fluid-attenuated inversion recovery images, and mild encephalatrophy ofthe olfactory bulbs and temporal lobes. The activity of lysosomal acid β-galactosidase inleukocytes was negligible, resulting in the biochemical diagnosis of GM1 gangliosidosis.Histologically, swollen neurons characterized by accumulation of pale, slightly granularcytoplasmic materials were observed throughout the central nervous system. Dysmyelinationor demyelination and gemistocytic astrocytosis were observed in the white matter.Ultrastructually, membranous cytoplasmic bodies were detected in the lysosomes of neurons.However, genetic analysis did not identify the c.1448G>C mutation, which is the singleknown mutation of feline GM1 gangliosidosis, suggesting that the cat was affected with anew variant of the feline disease.