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PubMed This is a summary of 7 peer-reviewed journal articles Updated
Pediatrics

Symptoms and Day-to-Day Impact

At a Glance

Beta-mannosidosis affects children differently. Common concerns can include hearing loss, developmental and language delays, low muscle tone, behavior changes, seizures, swallowing or breathing problems, dental findings, and skin lesions, so support is individualized.

Living with a diagnosis of beta-mannosidosis means navigating a unique and often unpredictable path. Because the condition affects how cells process waste, the symptoms can touch many different parts of a child’s life—from how they hear and speak to how they move and behave [1]. It is incredibly important to remember that because this condition is so rare and variable, your child may only experience a few of these symptoms, and their severity can differ greatly from other reported cases [1][2].

Hearing and Communication

For many families, a change in hearing is an early clue. However, the timeline and type of hearing loss can vary significantly [1].

  • Variable Onset: In some cases, hearing loss is detected as early as a newborn hearing screening [2]. However, passing a newborn screen does not rule out hearing loss later, as other children may be identified around age 2 or even as late as age 12 [2][3].
  • Types of Hearing Loss: A specialist will need to determine if the hearing loss is sensorineural (related to the inner ear or nerve pathways), conductive, or mixed [1][2].
  • Impact on Daily Life: Hearing loss often occurs alongside language delays, making communication a central focus of daily support [2]. While hearing aids can help, an individualized approach is essential. Your team may discuss early-intervention speech therapy, visual communication aids, augmentative and alternative communication (AAC) devices, sign language, or cochlear-implant assessments if clinically appropriate [2][4].

Neurodevelopment and Behavior

The brain and nervous system are frequently affected. Intellectual disability and developmental delays are among the most common symptoms reported in medical literature [1].

  • Developmental Milestones: Many children experience global developmental delay [5]. You might notice hypotonia (low muscle tone or “floppiness”) starting in late infancy [6][5]. Some families have reported developmental regression, where a child loses skills they once had, though this is not seen in every child [1].
  • Behavioral Patterns: Behavioral challenges can be a significant part of daily life. These may include hyperactivity, impulsivity, or repetitive routines [1][3]. While some routines may resemble obsessive-compulsive behavior, they are part of the broader developmental profile and should be managed with supportive therapies [1].
  • Neurological Changes: Seizures and difficulties with walking (gait disturbances) have been reported in some individuals [2][1].

Physical and Medical Concerns

Beta-mannosidosis can also affect physical health in ways that require individualized medical attention.

  • Respiratory and Swallowing Health: Recurrent respiratory infections, such as bronchitis or pneumonia, are reported in some individuals [3][7]. Some children also experience dysphagia (swallowing difficulties), which can make mealtimes stressful and increase the risk of chest infections [1].
  • Dental Health: Unique dental features have been documented in some cases, including macroglossia (an enlarged tongue), gingival overgrowth (excessive gum tissue), and a higher risk for cavities [7]. Because these issues can make brushing difficult, an early preventative dental schedule is recommended [7].
  • Skin Findings: Some individuals develop angiokeratomas [3]. These are small, dark red or purple spots on the skin. They are non-specific lesions (meaning they happen in many conditions) and are usually not painful, but any new or changing skin lesions should be evaluated by a doctor [3].

Every child with beta-mannosidosis has a unique profile of strengths and challenges. Your child’s care team will help you prioritize which therapies and educational supports—such as an Individualized Education Program (IEP)—will best improve your child’s comfort, function, and quality of life.

Common questions in this guide

What symptoms can beta-mannosidosis cause in children?
Beta-mannosidosis can affect hearing, speech and language, learning and development, muscle tone, movement, behavior, and sometimes seizures. Some children also have swallowing or breathing problems, dental changes, recurrent respiratory infections, or angiokeratomas, which are small dark skin spots. Symptoms and severity vary widely, so a child may have only a few of these features.
Can hearing loss appear later if a newborn hearing screen was normal?
Yes. Some children with beta-mannosidosis have hearing loss found during newborn screening, while others are diagnosed around age 2 or later in childhood. An audiology evaluation can determine the type of hearing loss and guide hearing aids or other communication support.
What communication support might help a child with beta-mannosidosis?
Support is individualized and may include hearing aids, early speech therapy, visual communication tools, sign language, or communication devices. A cochlear-implant assessment may be considered when clinically appropriate. Audiology and communication specialists can help match supports to the child's hearing and development.
How can beta-mannosidosis affect behavior and development?
Children may have global developmental delay, intellectual disability, low muscle tone, hyperactivity, impulsivity, or repetitive behaviors. Some families report loss of previously learned skills, but this does not occur in every child. Developmental, behavioral, and educational supports can be tailored to the child's needs.
What swallowing and breathing concerns should caregivers watch for?
Swallowing difficulties can make meals stressful and may increase the risk of chest infections. Recurrent bronchitis or pneumonia, or ongoing difficulty during meals, should be discussed with the child's care team, and swallowing concerns may warrant a clinical feeding evaluation.
What dental problems can occur with beta-mannosidosis?
Some children develop an enlarged tongue, excess gum tissue, or more cavities, and these changes can make brushing harder. A pediatric dentist can help establish preventive visits and a practical daily oral-care routine.

Questions For You

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Questions to Ask Your Doctor

Curated prompts to bring to your next appointment.

  1. 1.What type of hearing loss does my child have, and what specific audiology and communication supports are recommended?
  2. 2.Has my child shown signs of swallowing difficulties that warrant a clinical feeding evaluation?
  3. 3.How can we best manage the behavioral challenges or repetitive behaviors we are seeing at home without assuming they are strict obsessive-compulsive disorder?
  4. 4.What is the plan for monitoring my child's neurological health, including identifying potential seizures?
  5. 5.Do you have recommendations for a pediatric dentist who can help us establish a preventive care routine?

References

References (7)
  1. 1

    Expanding the Phenotype Spectrum of β-Mannosidosis.

    Martin Rios AM, Gibbs LH, Stepien KM, et al.

    Neurology. Genetics 2025; (11(6)):e200317 doi:10.1212/NXG.0000000000200317.

    PMID: 41235131
  2. 2

    Phenotype variability in six new patients with beta-mannosidosis.

    Olivas M, Romano C, Martin A, et al.

    Molecular genetics and metabolism 2026; (149(1-2)):110230 doi:10.1016/j.ymgme.2026.110230.

    PMID: 42600418
  3. 3

    β-Mannosidosis caused by a novel homozygous intragenic inverted duplication in MANBA.

    Blomqvist M, Smeland MF, Lindgren J, et al.

    Cold Spring Harbor molecular case studies 2019; (5(3)) doi:10.1101/mcs.a003954.

    PMID: 30886116
  4. 4

    Variant c.2158-2A>G in MANBA is an important and frequent cause of hereditary hearing loss and beta-mannosidosis among the Czech and Slovak Roma population- evidence for a new ethnic-specific variant.

    Safka Brozkova D, Varga L, Uhrova Meszarosova A, et al.

    Orphanet journal of rare diseases 2020; (15(1)):222 doi:10.1186/s13023-020-01508-3.

    PMID: 32847582
  5. 5

    Familial Global Developmental Delay Secondary to β-Mannosidosis.

    Gowda VK, Nagarajan B, Suryanarayana SG, Srinivasan VM

    Journal of pediatric neurosciences 2021; (16(2)):149-152 doi:10.4103/jpn.JPN_65_20.

    PMID: 35018184
  6. 6

    Biochemical and clinical response after umbilical cord blood transplant in a boy with early childhood-onset beta-mannosidosis.

    Lund TC, Miller WP, Eisengart JB, et al.

    Molecular genetics & genomic medicine 2019; (7(7)):e00712 doi:10.1002/mgg3.712.

    PMID: 31115173
  7. 7

    Oral manifestation and dental treatment of pediatric patient with beta-mannosidosis: A case report.

    Alshoraim MA, Al Agili DE

    SAGE open medical case reports 2021; (9()):2050313X211065796 doi:10.1177/2050313X211065796.

    PMID: 34925842

This page is for informational purposes only and does not constitute medical advice. Your child's care team should guide evaluation and support for beta-mannosidosis.