What is alpha-mannosidosis?
Alpha-mannosidosis is an ultra-rare, inherited condition known as a lysosomal storage disorder that causes a range of symptoms. It occurs when the body is unable to make an enzyme that breaks down certain glycoproteins, which are a type of sugar, in cells. This causes the sugars to build up in part of the cell called a lysosome, which can damage organs and tissues throughout the body.
a rare disease
1 in 500,000-
All forms are progressive,
independent of severity
Symptoms may first
become evident in infancy
or later in adolescence
What causes alpha-mannosidosis?
Alpha-mannosidosis is caused by hereditary mutations in a gene called MAN2B1.
What is a hereditary mutation?
Hereditary mutations are inherited from one’s father or mother, or in the case of alpha-mannosidosis, from both parents.
What is MAN2B1?
The gene MAN2B1 contains the information to make the enzyme α-mannosidase, which normally helps to break down complex sugars called oligosaccharides. Oligosaccharides are used to build bones, cartilage, skin, tendons, and many other tissues in the body.
What happens when α-mannosidase is not working properly?
A defect in the activity of α-mannosidase means that an individual is not able to correctly recycle old oligosaccharides. Due to this, partially broken-down mannose-containing chemicals remain stored in the body and begin to build up over time. This causes progressive damage to cells. Infants may show only a few signs of the disease, but as the disease progresses, symptoms start to appear.
What are the symptoms of alpha-mannosidosis?
Symptoms of alpha-mannosidosis include:
- Hydrocephalus (fluid build-up in the brain)
- Recurrent infections
- Immune deficiency
- Hearing loss
- Skeletal abnormalities (such as scoliosis, which is a curvature of the spine)
- Cognitive impairment
- Coarse facial features
- Disturbed motor function (such as muscle weakness and joint abnormalities, which may appear as clumsiness)
- Developmental delay
Symptoms can vary greatly from person to person and may change as patients get older.
Alpha-mannosidosis is a progressive disease, meaning symptoms will get worse over time as disease progresses.
- Hearing loss
- Delayed speech, motor, or mental functions
- Fluid build-up in the brain in the first year of life
2nd to 3rd decade of life
- Muscular weakness
- Ataxia (problems with coordination or balance)
- Skeletal abnormalities
- Joint problems
- Psychiatric symptoms
- Inability to achieve social independence
- Life expectancy unknown, although living to over 50 years old is not uncommon