Preferred Label : Mannosidosis, alpha b, lysosomal;
Symbol : MANSA;
CISMeF acronym : MANSA;
Type : Phenotype, molecular basis known;
Alternative titles and symbols : Alpha-mannosidase b deficiency; Lysosomal alpha-D-mannosidase deficiency; ALPHA-MANNOSIDOSIS;
Description : Alpha-mannosidosis is an autosomal recessive lysosomal storage disease characterized
by mental retardation, coarse facial features, skeletal abnormalities, hearing impairment,
neurologic motor problems, and immune deficiency. Expression of the disease varies
considerably, and there is a wide spectrum of clinical findings and severity. Affected
children are often normal at birth and during early development. They present in early
childhood with delayed psychomotor development, delayed speech, and hearing loss.
Additional features include large head with prominent forehead, rounded eyebrows,
flattened nasal bridge, macroglossia, widely spaced teeth, dysostosis multiplex, and
motor impairment (summary by Malm and Nilssen, 2008). - Classification Systems Two
classification systems have been used to describe the clinical presentation of alpha-mannosidosis.
The earlier system delineated a more severe 'type I,' which shows infantile onset,
rapid mental deterioration, hypotonia, splenomegaly, severe dysostosis multiplex,
and severe recurrent infections, often resulting in death by age 8 years. Individuals
with the less severe 'type II' show normal early development with later childhood
development of mental retardation, hearing loss, coarse facies, neurologic deterioration,
and survival well into adulthood (summary by Desnick et al., 1976 and Gotoda et al.,
1998). A later classification system delineated 3 clinical types. Type 1 is the mildest
form, with onset after age 10 years, without skeletal abnormalities and very slow
progression. Type 2 is a moderate form, with onset before age 10 years, presence of
skeletal abnormalities, and slow progression with development of ataxia by age 20
to 30 years. Type 3 is the severe form, with onset in early infancy, skeletal abnormalities,
and obvious progression leading to early death from primary central nervous system
involvement or myopathy. Most patients belong to clinical type 2 (summary by Malm
and Nilssen, 2008). Despite the clinical heterogeneity of the disorder, there are
no apparent genotype/phenotype correlations (Berg et al., 1999; Riise Stensland et
al., 2012).;
Inheritance : Autosomal recessive;
Molecular basis : Caused by mutation in the alpha-mannosidase gene (MAN2B1, 609458.0001);
Laboratory abnormalities : Increased urinary mannose-containing oligosaccharides; Decreased lysosomal alpha-mannosidase activity in plasma and leukocytes;
Prefixed ID : #248500;
Origin ID : 248500;
UMLS CUI : C0024748;
Currated CISMeF NLP mapping
- DO Cross reference
- Genes related to phenotype
- HPO term(s)
- ORDO concept(s)
- Semantic type(s)
- UMLS correspondences (same concept)
- Validated automatic mappings to NTBT
