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How is alpha-mannosidosis diagnosed?

Alpha-mannosidosis is not easy to identify and sometimes patients go years before receiving a proper diagnosis. However, since alpha-mannosidosis is a progressive condition, early diagnosis is key to starting treatment and minimizing symptoms.

Symptoms that may suggest alpha-mannosidosis

Young patients:
Hearing impairment with speech delay should prompt your doctor to look for additional symptoms.


Older patients:
Cognitive and motor impairment might warrant further investigation.

Definite diagnosis may involve testing for the presence of certain sugars in urine, blood tests, and genetic and enzyme testing may be used for confirmation.

Your (or your child’s) doctor can provide you with further information and recommend the right tests should alpha-mannosidosis be suspected.

How is alpha-mannosidosis inherited?

Alpha-mannosidosis is caused by recessive genes. If an adult carrying the abnormal gene has a partner who is also a carrier, there is a 25% chance with every pregnancy that the baby will have alpha-mannosidosis. However, since the disease is so rare, the chance of having a partner who is another carrier is also rare.

There is a 66% chance that an unaffected sibling of a person with alpha-mannosidosis may be a carrier of the disease.

How alpha-mannosidosis is passed down in a family: If one child has alpha-mannosidosis, there is a 1 in 4 chance of the disease also impacting future children.