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Intestinal Cobalamin Malabsorption Border Collie Type (IGS)
| Acronym: | IGS |
| Gene: | CUBN |
| Mutation: | c.8392delC |
| Inheritance: | Autosomal recessive |
| Sample type: | Cheek Swab, Whole Blood (EDTA) |
Genetics and characteristics
Intestinal cobalamin malabsorption Border Collie type is an inherited disease affecting Border Collies. Cobalamin, known as vitamin B12, plays an important role in many metabolic and synthesis pathways. Animals, as well as other higher organisms, are unable to synthesize cobalamin and need to obtain it by dietary intake. The uptake of dietary cobalamin requires several endogenous proteins. In Border Collies a mutation in a gene coding for cubilin occurs, a protein that together with amnionless protein constitutes a receptor for the cobalamin-GIF complex. The mutation leads to cobalamin malabsorption which results in low levels of serum cobalamin, hyperhomocysteinemia, and methylmalonic aciduria. Affected dogs are about 1 year old when diagnosed. Clinical signs of Intestinal cobalamin malabsorption in the Border Collie type include diarrhea, inappetence, poor body condition, and failure to grow. Clinical recovery can be achieved with regular parenteral cobalamin supplementation. The late recognition of the disease has contributed to a wide dispersion and a 6% carrier rate of the disease allele.
Results Reported As
Test Result |
Interpretation of test result |
CLEAR |
Tested mutation was not detected in animal with „clear“ result. Animal tested as clear has wild-type allele in homozygous state (i.e. two pairs of healthy alleles). It will not develop disease caused by tested mutation.* It will pass only wild-type allele to its offspring. |
CARRIER |
Tested mutation was detected in animal with „carrier“ result. Animal tested as carrier has one wild-type and one mutation allele, it is in heterozygous state. It will not develop disease caused by tested mutation.* It can pass wild-type or mutation allele to its offspring. |
AFFECTED |
Tested mutation was detected in animal with „affected“ result. Animal tested as affected has two copies of mutation alleles affecting the gene. It is likely the animal will experience a genetic disorder due to this mutation.** It will pass only mutation allele to its offspring. |
*Test excludes only tested mutation but not possible unknown mutations or factors that can lead to similar condition/symptoms.
** Potential unknown mutations or multiple other factors can possibly affect the likelihood of experiencing a genetic disorder.
References:
Fyfe, J.C., Hemker, S.L., Venta, P.J., Fitzgerald, C.A., Outerbridge, C.A., Myers, S.L., and Giger, U. (2013). An exon 53 frameshift mutation in CUBN abrogates cubam function and causes Imerslund-Gräsbeck syndrome in dogs. Mol. Genet. Metab. 109, 390–396.
Owczarek-Lipska, M., Jagannathan, V., Drögemüller, C., Lutz, S., Glanemann, B., Leeb, T., and Kook, P.H. (2013). A frameshift mutation in the cubilin gene (CUBN) in Border Collies with Imerslund-Gräsbeck syndrome (selective cobalamin malabsorption). PLoS ONE 8, e61144.