Alpha-L-fucosidase deficiency


Autosomal recessive

Inheritance from both parents will result in the disease

Age range at onset:

Up to age 2

Specialists you may see:


A progressive condition primarily affecting the brain, those with Fucosidosis have worsening intellectual disability and typically develop dementia later in life. The most severe cases begin in infancy and result in death in late childhood. Milder cases see symptoms develop between the ages of 1 and 2 – these individuals may live until mid-adulthood.

Development of motor skills including the ability to walk is slow – any skills learned will deteriorate over time. Growth is impaired, while seizures, spasticity and respiratory infections are common. Distinctively coarse facial features can be recognised, including thickened lips and tongue, a broad nose with flattened bridge, a protruding forehead and large, low set ears. Bone development is abnormal and angiokeratomas are common. Those with Fucosidosis may have visceromegaly.


The FUCA1 gene, responsible for making the alpha-L-fucosidase enzyme, is mutated in Fucosidosis. When this gene is mutated, the enzyme cannot break down sugars, which accumulate and cause cells to malfunction and die.