Mannosidosis: patterns of storage and urinary excretion of oligosaccharides in the bovine model.

Mannose and glucosamine-containing oligosaccharides were extracted from tissues of variously aged calves with mannosidosis. Whereas storage in the brain, and to a lesser extent in the pancreas and lymph nodes, was cumulative, that in the liver was relatively stable over the time period followed. It is suggested that in this latter organ the 15--20% residual alpha-mannosidase activity attributable to the mutant enzyme might be sufficient to normalise function. In the kidney, levels actually fell over the first 15--20 weeks of life and thereafter remained constant. It is postulated that, in foetal life, storage is cumulative but, after birth, storage material is lost from the kidney into the urine by degeneration and/or desquamation of renal tubular cells. From 20 weeks the amount lost is in equilibrium with that formed or absorbed by the tubular cells.