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GTR Home > Conditions/Phenotypes > Deficiency of alpha-mannosidase

Deficiency of alpha-mannosidase

Synonyms
Alpha mannosidase B deficiency; Alpha-Mannosidosis; Lysosomal alpha-D-mannosidase deficiency; Mannosidosis, alpha B lysosomal
Modes of inheritance
Autosomal recessive inheritance (Orphanet)

Summary

Excerpted from the GeneReview: Alpha-Mannosidosis
The clinical phenotype of alpha-mannosidosis varies considerably, with a wide spectrum of clinical findings and broad variability in individual presentation. At least three clinical types have been suggested in untreated individuals: mild (clinically recognized after age ten years, with myopathy, slow progression, and absence of skeletal abnormalities); moderate (clinically recognized before age ten years, with myopathy, slow progression, and presence of skeletal abnormalities); and severe (obvious progression leading to early death from primary central nervous system involvement or infection). Core features of untreated individuals generally include early childhood-onset non-progressive hearing loss, frequent infections due to immunodeficiency, rheumatologic symptoms (especially systemic lupus erythematosus), developmental delay / intellectual disability, low tone, ataxia, spastic paraplegia, psychiatric findings, bone disease (ranging from asymptomatic osteopenia to focal lytic or sclerotic lesions and osteonecrosis), gastrointestinal dysfunction (including diarrhea, swallowing issues / aspiration, and enlarged liver and spleen), poor growth, eye issues (including tapetoretinal degeneration and optic nerve atrophy), cardiac complications in adults, and pulmonary issues (including parenchymal lung disease). However, with the advent of enzyme replacement therapy, the natural history of this condition may change. Long-term velmanase alfa (VA) treatment outcomes are still being elucidated, but may include improvement in hearing, immunologic profile, and quality of life (improved clinical outcomes for muscle strength). Similarly, affected individuals who underwent hematopoietic stem cell transplantation (HSCT) experienced improvement in development (with preservation of previously learned skills), ability to participate in activities of daily living, stabilization or improvement in skeletal abnormalities, and improvement in hearing ability, although expressive speech and hearing deficiencies remained the most significant clinical problems after HSCT.
Full text of GeneReview (by section):
Summary
GeneReview Scope
Diagnosis
Clinical Characteristics
Genetically Related (Allelic) Disorders
Differential Diagnosis
Management
Genetic Counseling
Resources
Molecular Genetics
Chapter Notes
References
Authors:
Can Ficicioglu
Karolina M Stepien
view full author information

Available tests

79 tests are in the database for this condition.

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Clinical tests (79 available)

Biochemical Genetics Tests

Molecular Genetics Tests

Genes See tests for all associated and related genes

  • Also known as: LAMAN, MANB, MAN2B1
    Summary: mannosidase alpha class 2B member 1

Clinical features

Help
Imported from Human Phenotype Ontology (HPO)

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