Feline Glycogen Storage Disease IV (GSD IV)
Feline glycogen storage disease IV (GSD IV) is a deficiency of the glycogen branching enzyme (GBE). GBE is an enzyme of glycogen synthesis, deficiency of which results in tissue deposition of an abnormal and poorly soluble poly-glucan resembling amylopectin.
The glycogen storage diseases (GSDs), are a group of autosomal recessive disorders of glycogen synthesis and degradation that result in disturbed glucose homeostasis and glycogen accumulation in various tissues. The GSDs are categorized according to the deficient enzyme activity and have been numbered in the chronological order of first documentation. Clinical signs of GSDs vary, depending on which enzyme is deficient, the severity of the enzyme defect, and the type and site of glycogen accumulation. Phenotypic variations between species have also been observed and may be due to metabolic adaptations leading to the relative dependence of species on dietary carbohydrate for glucose homeostasis.
In a family of Norwegian forest cats (NFC), kittens may have cardiopulmonary collapse and die at birth or develop progressive neuromuscular degeneration. There is no known treatment for this abnormality, but there is a genetic test available to detect carriers.
Fyfe, J.C., Kurzhals, R.L., Hawkins, M.G., Wang, P., Yuhki, N., Giger, U., Van Winkle, T.J., Haskins, M.E., Patterson, D.F., and Henthorn, P.S. (2007). A complex rearrangement in GBE1 causes both perinatal hypoglycemic collapse and late-juvenile-onset neuromuscular degeneration in glycogen storage disease type IV of Norwegian forest cats. Mol. Genet. Metab. 90, 383–392.
Shelton, L., and Helmrich, H.G. (2006). Heritable diseases and abnormalities in cats.