Alpha-Mannosidosis

Alpha-mannosidosis is a lysosomal storage disorder, first described by Swedish physician Okerman in 1967. In humans it is known to be caused by an autosomal recessive genetic mutation in the gene MAN2B1, located on chromosome 19, affecting the production of the enzyme alpha-D-mannosidase, resulting in its deficiency. Consequently, if both parents are carriers, there will be a 25% chance with each pregnancy that the defective gene from both parents will be inherited, and the child will suffer from the disease. There is a two in three chance that unaffected siblings will be carriers (Figure 1). In livestock alpha-mannosidosis is caused by chronic poisoning with swainsonine from locoweed.