Sorted By Test Name - Mayo Medical Laboratories

MANT
8773
MANN
8772
5 50.0-99.9 Strongly positive
6 > or =100 Strongly positive Reference values
apply to all ages.
Clinical References: Homburger HA: Allergic diseases. In Clinical Diagnosis and Management by
Laboratory Methods. 21st edition. Edited by McPherson RA, Pincus MR. WB Saunders, Publ, New York,
Chapter 53, Part VI, pp. 961-971, 2007
Alpha-Mannosidase, Fibroblasts
Clinical Information: Alpha-mannosidosis is an autosomal recessive lysosomal storage disorder
caused by reduced or absent acid alpha-mannosidase enzyme activity. This enzyme is involved in
glycoprotein catabolism, with absent or reduced activity resulting in the accumulation of undigested
mannose-containing complex oligosaccharides in the lysosomes. This eventually interferes with the
normal functioning of cells. Clinical features and severity of symptoms are widely variable within
alpha-mannosidosis, but in general, the disorder is characterized by skeletal abnormalities, immune
deficiency, hearing impairment, and mental retardation. Three clinical subtypes of the disorder have been
described and they vary with respect to age of onset and clinical presentation. Type 1 is generally
classified by a mild presentation and slow progression with onset after 10 years of age and absence of
skeletal abnormalities. Type 2 is generally a more moderate form with slow progression and onset prior to
10 years of age with skeletal abnormalities and myopathy. Type 3 is the most severe form and usually
presents with prenatal loss or severe central nervous system involvement leading to an early death. The
incidence of alpha-mannosidosis is estimated at 1 in 500,000 live births. A diagnostic work up for
alpha-mannosidosis may demonstrate slight elevations of oligosaccharides in urine (OLIGO/84340
Oligosaccharide Screen, Urine). Reduced or absent enzyme activity of acid alpha-mannosidase in
leukocytes can confirm a diagnosis. Sequencing of the MAN2B1 gene allows for detection of
disease-causing mutations in affected patients and identification of familial mutations allows for testing of
at-risk family members.
Useful For: Diagnosis of alpha-mannosidosis
Interpretation: Values