Beta-mannosidosis
(Redirected from Mannosidosis, beta A, lysosomal)
Beta-mannosidosis, also called lysosomal beta-mannosidase deficiency,[1] is a disorder of oligosaccharide metabolism caused by decreased activity of the enzyme beta-mannosidase. This enzyme is coded for by the gene MANBA, located at 4q22-25. Beta-mannosidosis is inherited in an autosomal recessive manner.[1] Affected individuals appear normal at birth, and can have a variable clinical presentation. Infantile onset forms show severe neurodegeneration, while some children have intellectual disability. Hearing loss and angiokeratomas are common features of the disease.[2][3]
Symptoms and signs[edit | edit source]
The initial affected individual described in 1986 had a complex phenotype, and was later found to have both beta-mannosidosis and Sanfilippo syndrome.[1] People have been described with a wide spectrum of clinical presentations from infants and children with intellectual disability to adults who present with isolated skin findings (angiokeratomas).[1]
Most cases are identified in the first year of life with respiratory infections, hearing loss and intellectual disability. Because of its rarity, and non-specific clinical findings, beta-mannosidosis can go undiagnosed until adulthood, where it can present with intellectual disability and behavioral problems, including aggression.[4][5]
Cause[edit | edit source]
In terms of causation several mutations in the MANBA gene is the cause of beta-mannosidosis. The cytogenetic location of the gene is 4q24, furthermore the condition is inherited in an autosomal recessive manner[6][3]
Mechanism[edit | edit source]
The pathophysiology of this condition, is better comprehended, if one first looks at the normal function of beta-mannosidase such as its function of breaking down disaccharides [medical citation needed]
Beta-mannosidase function is consistent with, it being a lysosomal enzyme catalyzing and thus involved in degradation route for N-linked oligosaccharide moieties(glycoproteins)[7]
Diagnosis[edit | edit source]
A diagnosis of beta-mannosidosis is suspected based on the persons clinical presentation. Urine testing to identify abnormal oligosaccharides is a useful screening test, and enzymatic analysis or molecular testing can be used for confirmation.[2]
Differential diagnosis[edit | edit source]
Diagnostic techniques for this condition can be done to offer a DDx, via lectin histochemistry to distinguish between α-mannosidosis and beta-mannosidosis.[8]
Treatment[edit | edit source]
In terms of beta-mannosidosis treatment there is none currently, individuals that exhibit muscle weakness or seizures are treated based on the symptoms(since there's no cure)[9]
See also[edit | edit source]
References[edit | edit source]
- ↑ 1.0 1.1 1.2 1.3 Online Mendelian Inheritance in Man (OMIM) 248510
- ↑ 2.0 2.1
- ↑ 3.0 3.1 Reference, Genetics Home. "beta-mannosidosis". Genetics Home Reference. Retrieved 2017-07-13.
- ↑ subscription required
- ↑ "Mannosidosis, beta A, lysosomal | Genetic and Rare Diseases Information Center (GARD) – an NCATS Program". rarediseases.info.nih.gov. Retrieved 2017-07-13.
- ↑ Reference, Genetics Home. "MANBA gene". Genetics Home Reference. Retrieved 2017-10-25.
- ↑ "OMIM Entry - * 609489 - MANNOSIDASE, BETA A, LYSOSOMAL; MANBA". www.omim.org. Retrieved 9 May 2018.
- ↑
- ↑
Further reading[edit | edit source]
External links[edit | edit source]
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