Fucosidosis

Fucosidosis is a lysosomal storage disorder. Lysosomes are the parts of a cell that break down and recycle used material. In fucosidosis, an enzyme called alpha-L-fucosidase is missing or very weak, so certain sugar-containing molecules are not fully broken down. They slowly build up in the brain, liver, spleen, skin and other tissues.

Severity varies a lot. Doctors used to describe a more severe type I that starts in infancy and a milder type II that moves more slowly. Many researchers now see it as one range, from severe to milder.

Fucosidosis is caused by changes in both copies of the FUCA1 gene. This gene holds the instructions for making the alpha-L-fucosidase enzyme.

It is inherited in an autosomal recessive pattern. Each parent usually carries one changed copy and has no symptoms. When both parents are carriers, each child has a 1 in 4 chance of being affected.

It is not caused by anything a parent did, and it cannot be caught from another person. It has been found more often in Italy, Cuba and some communities in the southwestern United States. A genetic counselor can explain what test results mean for brothers, sisters and future pregnancies.

The brain is especially sensitive to the buildup. Children often have delayed development and intellectual disability that worsens with age. Over time they may lose skills such as sitting, walking or talking, and their muscles may become stiff (spasticity). Some have seizures.

Other features can include slow growth, bone changes seen on x-rays (called dysostosis multiplex), a curved spine and stiff joints. Many children have frequent chest infections. Small dark red spots on the skin, called angiokeratomas, are a common clue. Hearing loss, eye and heart problems, an enlarged liver and spleen, and hernias can also occur.

How long people live varies widely. Some children decline quickly and die young, usually from chest infections and loss of brain function. But most reported patients have had a slower course, and some live into adulthood, though their needs usually grow over time.

Families often spend years going to appointments for development, breathing, bones, eyes and hearing, sometimes before anyone knows the cause. Care usually involves a team that may include metabolic doctors, neurologists, lung doctors, therapists and social workers.

As the condition progresses, children may need more help with moving, eating and breathing. Pain control, palliative care and family support are part of good care, not a sign of giving up. Teenagers and adults with milder disease benefit from a plan for moving from children’s to adult services.

Once the family’s gene changes are known, brothers and sisters can be tested. Finding an affected younger child early matters, because transplant is only considered before major brain decline.

Transplant is rarely used for fucosidosis. When a specialist team does consider one, the cells come from another person. Published cases have used unrelated volunteer donors and umbilical cord blood.

Brothers and sisters are tested first, because more than one child in a family can have the condition. At least one US transplant center has included fucosidosis in a research study of donor transplants for inherited metabolic disorders. That study is no longer taking new patients.

A shortage of registry donors is not the main barrier for this condition. Earlier diagnosis and better treatments are the bigger needs. Joining a registry still helps the many other patients who are waiting for an unrelated donor.