Symptoms and Diagnosis

Signs and symptoms vary amongst people who have the condition. In general, affected individuals may have intellectual disability, distinctive facial features, immunodeficiency, hearing impairment and skeletal abnormalities.1

Characteristic facial features can include a large head, prominent forehead, low hairline, rounded eyebrows, large ears, flattened bridge of the nose, protruding jaw, widely spaced teeth, overgrown gums, and large tongue.2

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At least three clinical types of Alpha Mannosidosis (mild, moderate, and severe) have been suggested, classified according to the severity of the symptoms.3

Type 1

MILD FORM

A mild form, clinically recognized after ten years of age, with absence of skeletal abnormalities, and very slow progression.

Type 2

MODERATE FORM

A moderate form, recognized before 10 years of age, with presence of skeletal abnormalities, slow progression and development of ataxia at age 20-30. This is the most common form.

Type 3

SEVERE FORM

A severe form, immediately recognized with skeletal abnormalities, and obvious progression, leading to an early death from primary central nervous system involvement or myopathy.

However, given the variety of mutations that have been documented, the broad range and severity of symptoms, and no link between particular mutations and symptomatology, the disease is considered clinically as a continuum, from mild to severe.4,5

Most Common Symptoms6,7

Symptoms and diagnosis of Alpha Mannosidosis

Hearing impairment (>90%)

Conductive and neurosensory

Central Nervous System involvement

Celebral atrophy and demyelination
Mental retardation (>90%)
• IQ 60-80
• Delayed development of speech
• Delayed motor and mental function

Impairment of physical endurance

Ataxia and muscular weakness (>60%)

Psychiatric symptoms (≥45%)

Hurler - like features (>90%)

• Large head and prominent forehead
• Flattened nasal bridge
• Prognathism
• Short neck

Immunodeficiency

• Leading to frequent infections

Skeletal abnormalities (>90%)

• Genu valgus
• Joint contractures

  1. Beck M Olsen KJ, Wraith JE et al. Natural history of alpha-mannosidosis: a longitudinal study. Orphanet J Rare Dis 2013;8:88
  2. Malm D, Nilssen O. Alpha-mannosidosis. Orphanet J Rare Dis 2008;3:21
  3. Malm D, Nilssen O. Alpha-mannosidosis. Orphanet J Rare Dis 2008;3:21
  4. Beck M Olsen KJ, Wraith JE et al. Natural history of alpha-mannosidosis: a longitudinal study. Orphanet J Rare Dis 2013;8:88
  5. Borgwardt L, Lund AM, Dali CI. Alpha-mannosidosis – a review of genetic, clinical findings and options for treatment. Pediatr Endocrinol Rev 2014;12 Suppl 1:185-91
  6. Malm D, Nilssen O. Alpha-mannosidosis. Orphanet J Rare Dis 2008;3:21.
  7. Malm D, et al. The natural course and complications of alpha-mannosidosis—a retrospective and descriptive study. J Inherit Metab Dis. 2014 Jan;37(1):79-82.

The information on this website is intended only to provide knowledge of Alpha Mannosidosis disease health topics. This information should not be used in place of advice from your GP or other healthcare professional. If in doubt please contact your doctor for advice. This website has been produced by Chiesi Pharmaceuticals. The website has been developed in accordance with industry and legal standards to provide information for healthcare professionals and the general public about Alpha Mannosidosis disease health topics. Chiesi Pharmaceuticals makes every reasonable effort to include accurate and current information. However, the information provided in this website is not exhaustive.