CLINICAL CHARACTERISTICS: Beta-mannosidosis is characterized by developmental delay (speech is more significantly affected than motor skills), mild-to-severe intellectual disability, behavioral abnormalities, sensorineural hearing loss, recurrent infections, angiokeratomas, seizures, and ataxia. Most individuals have no dysmorphic features; some have mild coarseness....
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Discussion
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Audiologists evaluating children with unexplained sensorineural hearing loss (damage to the inner ear or hearing nerve) and developmental or speech delay should be aware of Beta-Mannosidosis as a rare differential diagnosis warranting metabolic genetics referral.
Updated GeneReviews guidance on rare metabolic disorders with hearing involvement ensures audiologists and genetics teams have current, authoritative information to guide diagnostic workups and referrals.
- 01Beta-Mannosidosis is a rare lysosomal storage disorder (a condition where cellular waste builds up) caused by MANBA gene mutations.
- 02Core features include intellectual disability, severely impaired speech, and recurrent infections; hearing loss is a recognised associated feature.
- 03The GeneReviews entry was updated May 2026, reflecting the most current clinical guidance.
- 04Diagnosis involves enzyme activity testing and genetic confirmation; no curative therapy currently exists.
- 05Audiologists may be among the first clinicians to identify the hearing component of this multi-system disorder.
Beta-Mannosidosis is characterised by developmental delay with notably impaired speech.
guidelinesupported- PMID
- 42160655
- Journal
- GeneReviews (NCBI Bookshelf)
- Publication type
- review
- Evidence level
- 5
- Population
- Individuals with Beta-Mannosidosis, a rare inherited lysosomal storage disorder
- Intervention
- Characterisation and clinical guidance for Beta-Mannosidosis (MANBA gene mutations)
Primary outcomes
Clinical features including developmental delay and speech impairment; Diagnostic criteria and genetic testing guidance; Management recommendations