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Imerslund-Gräsbeck Syndrome, Beagle Type (IGS-BEA)

Imerslund-Gräsbeck Syndrome, Beagle Type (IGS-BEA)

Cobalamin Deficiency, Cubilin Deficiency, Imerslund-Grasbeck Syndrome, Vitamin B12 Deficiency, I-GS

Imerslund-Grasbeck Syndrome (IGS), also known as intestinal cobalamin malabsorption, is a disorder in which a dog is unable to absorb adequate levels of Vitamin B12. Absorption of Vitamin B12, also known as cobalamin, which occurs in the small intestine is inadequate in dogs affected with IGS and leads to a deficiency in this vitamin. Dogs that inherit this disease are born with a small amount of vitamin B12 that is quickly depleted and leads to symptoms of the disease within 6-12 weeks after birth. These symptoms can include failure to thrive and gain weight, lack of appetite, anemia, and lethargy. Symptoms will typically appear to intensify after eating. IGS can be managed with regular vitamin B12 diet supplementation, however without treatment this disease can progress to permanent brain and nervous system damage.

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These dogs have two copies of the normal gene and will neither develop intestinal cobalamin malabsorption nor pass this mutation to their offspring.


These dogs have one copy of the normal gene and one copy of the mutation associated with this disease. They will not develop intestinal cobalamin malabsorption but will, if bred, pass the mutation to 50% of its offspring, on average.


These dogs have two copies of the mutation associated with this disease and are susceptible to developing intestinal cobalamin malabsorption.

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Additional Details


Autosomal Recessive

Affected gene



Ch. 2




Drogemuller M, Jagannathan V, Howard J, Bruggmann R, Drogemuller C, Ruetten M, Leeb T, Kook PH. A frameshift mutation in the cubilin gene (CUBN) in Beagles with Imerslund–Grasbeck syndrome (selective cobalamin malabsorption) [PubMed: 24164695]