Beta-mannosidosis
Beta-mannosidosis is a rare inherited disorder affecting the way certain sugar molecules are processed in the body.
Signs and symptoms of beta-mannosidosis vary widely in severity, and the age of onset ranges between infancy and adolescence. Almost all individuals with beta-mannosidosis experience intellectual disability, and some have delayed motor development and seizures. Affected individuals may be extremely introverted, prone to depression, or have behavioral problems such as hyperactivity, impulsivity or aggression.
People with beta-mannosidosis may experience an increased risk of respiratory and ear infections, hearing loss, speech impairment, swallowing difficulties, poor muscle tone (hypotonia), and reduced sensation or other nervous system abnormalities in the extremities (peripheral neuropathy). They may also exhibit distinctive facial features and clusters of enlarged blood vessels forming small, dark red spots on the skin (angiokeratomas).
What does it mean if a disorder seems to run in my family?
What is the prognosis of a genetic condition?
Beta-mannosidosis is believed to be a very rare disorder. Approximately 20 affected individuals have been reported worldwide. It is difficult to determine the specific incidence of beta-mannosidosis, because people with mild or non-specific symptoms may never be diagnosed.
What information about a genetic condition can statistics provide?
Why are some genetic conditions more common in particular ethnic groups?
Mutations in the MANBA gene cause beta-mannosidosis.
The MANBA gene provides instructions for making the enzyme beta-mannosidase. This enzyme works in the lysosomes, which are compartments that digest and recycle materials in the cell. Within lysosomes, the enzyme helps break down complexes of sugar molecules (oligosaccharides) attached to certain proteins (glycoproteins). Beta-mannosidase is involved in the last step of this process, helping to break down complexes of two sugar molecules (disaccharides) containing a sugar molecule called mannose.
Mutations in the MANBA gene interfere with the ability of the beta-mannosidase enzyme to perform its role in breaking down mannose-containing disaccharides. These disaccharides gradually accumulate in the lysosomes and cause cells to malfunction, resulting in the signs and symptoms of beta-mannosidosis.
Learn more about the gene associated with beta-mannosidosis
MANBA
How can gene mutations affect health and development?
Inheritance Pattern
This condition is inherited in an autosomal recessive pattern, which means both copies of the gene in each cell have mutations. The parents of an individual with an autosomal recessive condition each carry one copy of the mutated gene, but they typically do not show signs and symptoms of the condition.
What are the different ways in which a genetic condition can be inherited?
More about Inheriting Genetic Conditions
Diagnosis & Management Links
Genetic Testing Information (2 links)
What is genetic testing?
Genetic Testing Registry: Beta-D-mannosidosis
Research Studies from ClinicalTrials.gov (1 link)
How we cover diagnosis and management of health conditions
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Other Names for This Condition
beta-D-mannosidosis
beta-mannosidase deficiency
lysosomal beta A mannosidosis
lysosomal beta-mannosidase deficiency
Health Information from MedlinePlus (2 links)
Health Topic: Carbohydrate Metabolism Disorders
Health Topic: Genetic Brain Disorders
Genetic and Rare Diseases Information Center (1 link)
Mannosidosis, beta A, lysosomal
Orphanet: Beta-mannosidosis
Patient Support and Advocacy Resources (3 links)
ISMRD: The International Advocate for Glycoprotein Storage Diseases
Metabolic Support UK
The MPS Society (UK)
Medical Genetics Database from MedGen (1 link)
Alkhayat AH, Kraemer SA, Leipprandt JR, Macek M, Kleijer WJ, Friderici KH. Human beta-mannosidase cDNA characterization and first identification of a mutation associated with human beta-mannosidosis. Hum Mol Genet. 1998 Jan;7(1):75-83.
Bedilu R, Nummy KA, Cooper A, Wevers R, Smeitink J, Kleijer WJ, Friderici KH. Variable clinical presentation of lysosomal beta-mannosidosis in patients with null mutations. Mol Genet Metab. 2002 Dec;77(4):282-90.
Gort L, Duque J, Fabeiro JM, Zulaica A, Coll MJ, Chabás A. Molecular analysis in two beta-mannosidosis patients: description of a new adult case. Mol Genet Metab. 2006 Dec;89(4):398-400. Epub 2006 Aug 14.
OMIM: MANNOSIDOSIS, BETA A, LYSOSOMAL
Molho-Pessach V, Bargal R, Abramowitz Y, Doviner V, Ingber A, Raas-Rothschild A, Ne'eman Z, Zeigler M, Zlotogorski A. Angiokeratoma corporis diffusum in human beta-mannosidosis: Report of a new case and a novel mutation. J Am Acad Dermatol. 2007 Sep;57(3):407-12. Epub 2007 Apr 8. Review.
Uchino Y, Fukushige T, Yotsumoto S, Hashiguchi T, Taguchi H, Suzuki N, Konohana I, Kanzaki T. Morphological and biochemical studies of human beta-mannosidosis: identification of a novel beta-mannosidase gene mutation. Br J Dermatol. 2003 Jul;149(1):23-9.
Zhu M, Lovell KL, Patterson JS, Saunders TL, Hughes ED, Friderici KH. Beta-mannosidosis mice: a model for the human lysosomal storage disease. Hum Mol Genet. 2006 Feb 1;15(3):493-500. Epub 2005 Dec 23.
Reviewed: January 2008