The symptoms of fucosidosis vary greatly even among individuals within the same family. Fucosidosis can be rapidly progressive causing severe, life-threatening complications in children or develop during adolescence and progress more slowly eventually causing serious complications in adulthood. In the past, fucosidosis was sometimes separated in type I and type II. However, researchers now believe that fucosidosis represents a disease spectrum with a wide variety of expression. Cases labeled fucosidosis type I (early onset, rapid progression) represent the severe end of the spectrum and those labeled fucosidosis type II represent the mild end.
Infants with severe forms of fucosidosis may not exhibit any symptoms until 6 months to one year of life. Initial symptoms may be associated with mental and motor deterioration such as delayed acquisition of skills required to coordinate mental and muscular activities (psychomotor retardation). Physicals findings may also develop including coarse facial features, thickened lips and tongue, multiple deformities of the bone (mild dysostosis multiplex), loss of muscle tone (hypotonia) resulting in “floppiness” and growth retardation. Progressive neurological deterioration may result in a variety of symptoms including intellectual disability, various movement disorders and/or uncontrolled rigid extensions and rotations of the arms, legs, fingers, and toes (decerebrate rigidity). Severe fucosidosis often progresses to cause life-threatening neurodegenerative complications and/or severe, progressive loss of weight and muscle mass (cachexia), usually within the first few years of life.
Less common findings associated with severe forms of fucosidosis include abnormally enlarged internal organs (visceromegaly), such as the liver and spleen (hepatosplenomegaly) or heart (cardiomegaly), seizures, hearing loss, abnormal curvature of the spine (kyphoscoliosis), and repeated respiratory infections. Some affeced individuals may sweat excessively and their sweat may contain abnormally high levels of salt.
In some less severe cases, the symptoms associated progressive deterioration of the central nervous system may not become obvious until the age of 18 months to three years. The symptoms of less severe forms of fucosidosis are similar to the more severe forms, but tend to be milder with slower progression. Affected individuals may develop wart-like growths (angiokeratomas) on the skin around the age of two years. These lesions occur mainly on the abdomen, buttocks, thighs, and/or external genitalia. Some individuals may experience fixation of certain joints in a permanently flexed position (contractures), involuntary muscle spasms (spasticity) that result in slow, stiff movements of the legs and inadequate ability to sweat (anhidrosis). Individuals with less severe forms of fucosidosis may live well into their second, third or fourth decades before the disorder progresses to cause life-threatening complications.