Glycogenosis Ia (GSD) in German Pinschers

Glycogenosis (GSD, Glycogen Storage Disease) is a severe disorder of glycogen metabolism characterized by accumulation of glycogen, especially in the liver. Symptoms include severe liver enlargement, general failure to thrive, lethargy, coma and death.

In the German Pinscher, the disease is caused by mutation c.634_635insN[76] in the G6PC gene, which encodes the enzyme glucose-6-phosphatase that plays an important role in the conversion of glucose-6-phosphate to glucose. The mutant G6PC has a 15-fold reduction in activity, leading to severe hypoglycaemia and glycogen storage and progressive hepatomegaly.

The mode of inheritance of the mutation is autosomal recessive. This means that only individuals who inherit the mutated gene from both parents will develop the disease. Carriers of the mutated gene are clinically healthy but pass the mutation on to their offspring. In the case of a mating between two heterozygous individuals, theoretically 25% of the offspring will be completely healthy, 50% of the offspring will be carriers and 25% of the offspring will inherit the mutated gene from both parents and will therefore be affected by the disease.

The genetic test can clearly reveal the genotype of the animal and is a useful tool for breeders to prevent unintentional breeding of affected puppies.

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References:

Christen, M., Reineking, W., Beineke, A., Jagannathan, V., Baumgärtner, W., Leeb, T. : Polyadenine insertion disrupting the G6PC1 gene in German Pinschers with glycogen storage disease type Ia (GSD1A). Anim Genet 52:900-902, 2021. Pubmed reference: 34610166