Mannosidoses are inherited lysosomal storage disorders being caused by mutations in the genes. There are 2 types of mannosidoses: Alpha-mannosidosis and Beta-mannosidosis. Both types are being caused by a deficiency or dysfunction of a certain enzyme. Because of this deficiency or dysfunction the body cannot breakdown certain complex sugars which leads to the accumulation of these sugars in the cells. 

Mannosidoses has 2 different types:

1. Alpha-mannosidosis 
2. Beta-mannosidosis

All forms of mannosidoses are very rare. Good incidence numbers are not available.  It is estimated that alpha-mannosidosis occurs in one in every 500,000 people.

Mannosidosis is an autosomal recessive inherited metabolic disorder. Autosomal recessive means that a child can only have the disease if he or she received the affected gene from both his or her parents. Which gene is affected depends on the type of mannosidosis. 

• In Alpha Mannosidosis, there is a genetic mutation in the MAN2B1 gene. This genetic mutation causes a disruption in the production of the alpha-mannosidase enzyme, causing a deficiency or dysfunction of the enzyme.
• In Beta-mannosidosis, there is a genetic mutation in the MANBA gene.

• Alpha-mannosidosis
  In general, patients with Alpha-mannosidosis have a intellectual disability, bone abnormalities and characteristic facial features (large forehead, not well-developed teeth, large lower jaw). The severity of the disease is determined by its form. Alpha-mannosidosis has 2 forms (mild form and severe form). In the severe form, symptoms appear in the first year of life. Children with the severe form grow up to be between 3 and 10 years old. In the mild form, symptoms do not appear until later in life and the child initially develops normally.
• Beta-mannosidosis
  Symptoms in beta-mannosidosis can begin between childhood and adulthood. The symptoms can vary from patient to patient. Patients with Beta-mannosidosis may experience muscle weakness, intellectual disability, infections, difficulty swallowing and talking.

If the doctor suspects that you or your child may have mannosidosis, he or she will do a number of tests to make the diagnosis. The following tests may be involved:

• Physical examination
• Urine sampling
• Blood sampling
• DNA test 

Unfortunately, mannosidosis cannot be cured. To slow down the disease, enzyme replacement therapy is available for Alpha-mannosidosis. However, this treatment is not suitable for every patient. Therefore, each patient will first be assessed for eligibility for enzyme replacement therapy. For Beta-mannosidosis, treatment consists mainly of symptom control.

Patients with mannosidosis will need to be followed throughout their lives. Because patients deal with a variety of symptoms, the patient will see different specialists. 

Our scheduling coordinator will schedule appointments for you. To minimize hospital visits for you and/or your child, we will try to schedule appointments with different specialists on the same day whenever possible. 

Please also visit our team page to meet our specialists.