Alpha-Mannosidosis is an inherited lysosomal storage disease characterized by immune deficiency, facial and skeletal abnormalities, hearing impairment, and intellectual deficit.
It occurs in approximately 1 in 500,000 live births.
The disease is caused by a deficiency of lysosomal alpha-mannosidase. Alpha-Mannosidosis is hereditary, is transmitted in an autosomal recessive manner and is caused by mutations in the MAN2B1 gene, located on chromosome 19 (19 p13.2-q12).
The diagnosis is established by measuring the activity of acid alpha-mannosidase in leukocytes or other nucleated cells and can be confirmed by genetic testing. The increase in high mannose oligosaccharides in urine is indicative (nondiagnostic) disease.
The differential diagnosis includes other lysosomal storage diseases, such as various forms of mucopolysaccharidosis.
Genetic counseling should be proposed to explain the nature of the disease and locate individuals carrying the mutation.
Prenatal diagnosis is possible, based on both biochemical and genetic methods.