Intestinal cobalamin malabsorption Border Collie Type (IGS)
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 cobalamin-GIF complex. 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 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 disease has contributed to a wide dispersion and 6% carrier rate of the disease allele.
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.