Sialidosis is a rare genetic condition caused by changes (mutations) in the NEU1 gene which cause not enough NEU1 enzyme to be made. The NEU1 enzyme helps the cells in our body breakdown a particular type of sugar. Without the enzyme, this sugar builds up in nerve cells and bone marrow. There are two main types of sialidosis: Type 1 is a milder form with symptoms usually developing in the teen years and Type 2 is more severe and is broken down into three subtypes: congenital (symptoms develop in the fetus before birth), infantile (symptoms develop soon after birth) or juvenile (symptoms develop in late childhood).
Timing and severity of the symptoms will vary with type, but in general many organs and tissues are affected. Common symptoms include red spots in the eyes (cherry red spots), swelling throughout body, vision problems, leg tremors, involuntary muscle contractions, low muscle tone, and seizures. People with sialidosis may also have “coarse” facial features, including a flat nose, puffy eyelids, large gums, and a large tongue. Sialidosis is progressive, meaning it gets worse over time.
Type 1 does not affect life expectancy or intelligence, but a wheelchair may be needed in adulthood. Babies with congenital type 2 usually die before or shortly after birth. Children with infantile type 2 usually develop intellectual disabilities and hearing loss and are shorter than average children. Sadly they usually do not live beyond their early teen years. Juvenile type 2 may affect intellectual abilities and life expectancy depends on the severity of symptoms.
The diagnosis is confirmed by genetic testing. Although there is no cure, there are treatments which may help manage the symptoms. Research is ongoing, so talk to your child’s doctor about current treatment options. Genetic counselors and support groups are also good resources of information and can help connect you with other families affected by the sialidosis.