Fucosidosis a glycoprotein storage disorder and involves genetic mutations of the FUCA1 gene, which, in turn, profoundly inhibits the functionality of the alpha-L-fucosidase enzyme, responsible for cleaving the fucose sugar molecule at the end of the catabolism process.
Fucosidosis is a disorder that may have a variable presentation even in individuals belonging to one family. Even though the symptoms elicited remain the same, patients may be affected by fucosidosis with an early onset and rapid progression, or a disease that is diagnosed during adolescence and progresses slowly with less profound symptoms.
The most severe type of fucosidosis tends to initially manifest at a time between the 6th month to the 1st year of an infant's life. Symptoms include psychomotor retardation, namely the slowing-down of emotional and physical reactions to various stimuli. Other findings that may be revealed in a physical examination may include :
Fucosidosis primarily leads to a neurodegeneration due to central nervous system myelin loss. This is evident by means of mental retardation, loss of coordination, and rigidity of the extremities that involves extension and rotation (decerebrate rigidity)   . As the disease progresses, the loss of weight and muscle mass sustained may constitute life-threatening sequelae that can lead to a patient's demise even within the first years of life.
Other signs related to fucosidosis include visceromegaly that can affect the spleen, liver, and heart, epilepsy, hearing impairment or total hearing loss, kyphoscoliosis, and persistent respiratory infections. Hyperhidrosis is another potential symptom.
Symptoms are identical in less severe as well as more severe forms of Fucosidosis. However, they may be milder and may progress more slowly in the less severe forms. Angiokeratomas usually form on the skin at the age of approximately 2 years and are primarily found on the abdomen, thighs, and genital areas. Contractures, spasticity, and anhidrosis may also complicate the clinical picture.
The first step towards a successful diagnosis of Fucosidosis is a detailed medical history and a meticulous clinical examination. The patients are, in the majority of the cases, in their first year of life and parents report signs associated with mental retardation; the infant also appears to be lacking in terms of growth and neurological development. Characteristic skeletal and facial features are also noticeable and may indicate the diagnosis. Further tests that may be employed in order to diagnose Fucosidosis include: