Imerslund-Gräsbeck Syndrome

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Find out if your Border Collie could develop Imerslund-Gräsbeck Syndrome at CAGT.

Turnaround 1-2 weeks
Breed(s) , , ,
OMIA OMIA001786-9615
Aliases ,


Imerslunf-Gräsbeck Syndrome (IGS) is a genetic disorder in which cobalamin (Vitamin B12) is not absorbed from food in the intestine, resulting in a cobalamin deficiency. Lack of cobalamin leads to changes in the hematopoietic system, such as megaloblastic anemia (fewer red blood cells). Left untreated a chronic deficiency of cobalamin can lead to neurological symptoms due to irreversible damage of the brain and nervous system. Symptoms include anorexia, lethargy and failure to gain weight. Cobalamin malabsorption can be managed by supplementation with regular doses of cobalamin.

Autosomal Recessive

The single nucleotide deletion in the gene called CUBN that causes Imerslund-Gräsbeck Syndrome in Border Collie is Autosomal recessive. This means that dogs that carry two copies of the mutation (homozygotes) will almost certainly develop Imerslund-Gräsbeck Syndrome during their lives. Dogs that carry a single copy of the mutation (also known as carriers or heterozygotes) will not develop Imerslund-Gräsbeck Syndrome as a result of the CUBN mutation, but they will pass the mutation onto about half of any offspring they have. Breeding dogs that will not develop Imerslund-Gräsbeck Syndrome should be the breeder’s priority, with a reduction in mutation frequency within the whole breed being the secondary, longer-term target.

Carriers can be bred from safely, provided they are mated to a dog that has also been tested and is clear of the CUBN mutation (i.e. carry no copies of the mutation). If a carrier is mated to a clear dog approximately half of the resulting puppies will also be carriers, so should be tested themselves prior to breeding. Breeding carriers to tested, clear dogs is safe, in terms of avoiding dogs affected with Imerslund-Gräsbeck Syndrome, and will help to maintain the genetic diversity of a breed. It is therefore encouraged, particularly in the first few generations following the availability of a new genetic test, so that other desirable characteristics and traits can be preserved before the frequency of the disease mutation within the breed is gradually reduced.

Variant Single base pair deletion, c.8392delC
Assay Type Variant Specific
Inheritance Autosomal Recessive
Severity Low-Moderate: Affected animals experience discomfort or dysfunction of some kind, but life expectancy is not affected.

Owczarek-Lipska M, V Jagannathan, C Drögemüller et al. (2013) A Frameshift Mutation in the Cubilin Gene (CUBN) in Border Collies with Imerslund-Gräsbeck Syndrome (Selective Cobalamin Malabsorption). PLoS ONE. 8(4): e61144 . DOI: 10.1371/journal.pone.0061144.

Lutz S, AC Sewell, B Bigler et al. (2012) Serum cobalamin, urine methylmalonic acid, and plasma total homocysteine concentrations in Border Collies and dogs of other breeds. American Journal of Veterinary Research. 73(8): 1194-1199 . DOI: 10.2460/ajvr.73.8.1194 .