Intestinal cobalamin malabsorption / IGS (CUBN-related) - Beagle

What does this test assess?

This genetic test analyses the CUBN c.786delC variant in the Beagle. The condition is known as Imerslund-Gräsbeck syndrome, IGS, selective intestinal cobalamin malabsorption, intestinal cobalamin malabsorption, ICM, inherited vitamin B12 malabsorption and CUBN-related cubilin deficiency. CUBN encodes cubilin, part of the cubam complex required for uptake of vitamin B12, also called cobalamin, from the intestine.

What does this condition mean?

Vitamin B12 is needed for normal blood formation, growth, energy metabolism and nerve function. In IGS/ICM, the dog cannot absorb enough dietary vitamin B12 through the intestine. Natural stores become depleted in young puppies, leading to a combination of digestive, blood and metabolic problems.

In Beagles, signs can become visible at a young age. Owners often notice poor appetite, lethargy, poor weight gain and malaise, sometimes more clearly after eating. Clinically, non-regenerative anaemia, neutropenia, bone marrow changes, increased methylmalonic acid and urinary protein loss can be seen.

Inheritance and result

The trait is inherited as an autosomal recessive condition. Dogs with two copies of the tested CUBN variant develop IGS/ICM for this variant. Carriers have one copy, are usually healthy themselves, but can pass the variant to offspring.

• Clear: the tested variant was not detected.
• Carrier: one copy of the variant was detected; important for breeding plans.
• Affected: two copies were detected; this genotype causes CUBN-related IGS/ICM for this variant.

Practical value of this test

This test gives breeders and owners clear information before a mating is planned or when young dogs show signs compatible with vitamin B12 malabsorption. Because carriers can look normal, DNA testing is the most direct way to identify risk matings.

• Helps identify carriers before breeding.
• Reduces the risk of affected puppies from carrier x carrier matings.
• Provides targeted genetic context in young dogs with poor growth, lethargy or blood abnormalities.
• Supports transparent communication with buyers, veterinarians and breed clubs.