Glycogen Storage Disease type IV (GSD IV) in Norwegian Forest Cats
GSD IV leads to progressive organ dysfunction, generalized muscle atrophy, and eventual death in affected Norwegian Forest Cats.
Phenotype: Affected kittens may die at or soon after birth, but a few can appear clinically normal till about 5 months of age. These juveniles develop a persistent fever and later show signs of muscle tremors. The signs progress to generalized muscle atrophy and eventual death.
Mode of Inheritance: Autosomal recessive
Alleles: N = Normal, GSD = Glycogen storage disease type IV (GSD IV)
Breeds appropriate for testing: Norwegian Forest Cat
Explanation of Results:
Cats with N/N genotype will not have glycogen storage disease type IV and cannot transmit this GSD IV variant to their offspring.
Cats with N/GSD genotype will not have glycogen storage disease type IV, but are carriers. They will transmit this GSD IV variant to 50% of their offspring. Matings between two carriers are predicted to produce 25% kittens with glycogen storage disease type IV.
Cats with GSD/GSD genotype will have glycogen storage disease type IV, a fatal condition.
Norwegian Forest cats can inherit a defective glycogen branching enzyme (GBE) that causes a severe error in glycogen (sugar) storage in cells. Abnormal glycogen accumulates in muscle, liver, and neurons causing progressive organ dysfunctions. The disease is inherited as an autosomal recessive trait. Most, affected kittens may die at or soon after birth likely from an inability to produce energy. In rare instances, some affected kittens appear clinically normal until about 5 months of age when normal development ceases. These juveniles develop a persistent fever and later show signs of muscle tremors. The signs progress to generalized muscle atrophy and eventual death.
Glycogen storage disease IV (GSD IV) in the Norwegian Forest Cat is inherited in an autosomal recessive fashion. Two affected copies are necessary for the disease to manifest and both sexes are affected with equal frequency. Testing for GSD IV can help breeders identify carriers of GSD IV in Norwegian Forest Cats and select mates for breeding to avoid producing affected kittens.
Note: This test is specific for the GSD IV genetic defect that has been identified in Norwegian Forest Cats.