Genetic Test
The Cubam receptor complex plays a critical role in the absorption of cobalamin (vitamin B12).
This complex consists of two subunits: AMN (Amnionless) and CUBN (Cubilin).
Both proteins function together at the brush border of the small intestine epithelium, especially in the ileum, to mediate the receptor-mediated uptake of the intrinsic factor-cobalamin (IF-Cbl) complex.
AMN and CUBN are essential for maintaining each other's proper structure and function. A defect in either subunit disrupts normal cobalamin absorption.
Disease Description
Cobalamin (vitamin B12) is an essential vitamin produced by microorganisms and must be obtained from the diet.
The body absorbs cobalamin by binding it to a glycoprotein called intrinsic factor (IF).
Dogs with selective cobalamin malabsorption have genetic defects in the genes encoding the binding sites for the IF-Cbl complex, resulting in absent or nonfunctional receptors.
This rare congenital disorder leads to the absence of IF-Cbl receptor expression in the brush border of ileal and renal epithelial cells, impairing cobalamin absorption and causing systemic metabolic abnormalities.
