Plasma α-mannosidase activity as a means of detecting mannosidosis heterozygotes

Publisher Website
Google Scholar
Abstract
Extract Mannosidosis of Angus cattle, previously known as pseudolipidosis, is an inherited lethal nervous disease (Whittem and Walker, 1957 Whittem, J. H. and Walker, D. 1957. Neuronopathy and pseudolipidosis of Aberdeen-Angus calves. J. Path. Bact., 74: 281–288. [Google Scholar] ; Jolly, 1970 Jolly, R. D. 1970. Diagnosis and control of pseudolipidosis of Angus calves. N.Z. vet. J., 18: 228–229. [Taylor & Francis Online] [Google Scholar] , 1971 Jolly, R. D. 1971. The pathology of the central nervous system in pseudolipidosis of Angus calves. J. Path., 103: 113–121. [Google Scholar] ). It has recently been shown that this condition is due to an inborn error of lysosomal catabolism of glycoproteins in which a deficiency of α-mannosidase results in storage of an oligosaccharide containing glucosamine and mannose (Hocking et al., 1972 Hocking, J. D. , Jolly, R. D. and Batt, R. D. 1972. Deficiency of α-mannosidase in Angus cattle — An inherited lysosomal storage disease. Biochem. J., 128: 69–78. [Google Scholar] ). As such it is biologically similar to other inherited lysosomal storage diseases of man and animals (Jolly and Blakemore, 1973 Jolly, R. D. and Blakemore, W. F. 1973. Lysosomal storage diseases — An essay in comparative medicine. Vet. Rec., in press [Google Scholar] ). Whereas diseased calves have a near absolute deficiency of α-mannosidase, heterozygotes for this genotype have a partial deficiency of the enzyme. This observation could be exploited as a means of testing for heterozygous animals in the population at large. This paper augments earlier observations and describes some of the parameters that affect the level of α-mannosidase in normal individuals. The effects on enzyme activity of methods of collection and subsequent treatment of blood samples are also investigated.