What is Hunter syndrome (MPS II) ?

Hunter syndrome, also called mucopolysaccharidosis II or MPS II, is a rare, inherited disorder. Mainly affects boys. Their bodies cannot break down the sugar that builds bones, skin, tendons, and other tissues. These sugars accumulate in their cells and damage many parts of the body, including the brain. What exactly happens is individual for each person.

If your son has Hunter Syndrome, you can help him play, make friends, and do things other kids do, even though he may seem different from his friends.

While there is no cure for Hunter syndrome, there are ways to manage it and live with the symptoms.

Causes

Boys with this condition cannot make a certain protein because there is a problem with a small piece of their DNA called a gene that comes from their mother.

A father with Hunter syndrome will pass on the problematic gene to his daughter, but she will not develop the disease unless she receives the gene from her mother.

It is possible, but very, very unlikely, that someone can develop Hunter syndrome, even if no one else in the family has it.

Symptoms

When Hunter syndrome affects the brain, which is about 75% of the time, symptoms usually appear between the ages of 18 months and 4 years. They begin after about 2 years, when the disease is milder.

Hunter syndrome usually affects the appearance of a boy:

Large, round cheeks
Broad nose
Thick lips and a large tongue
Bushy eyebrows
Large head
Slowed growth
Thick, tough skin
Short, broad hands with stiff, curled fingers

He'll probably have these symptoms:

Joint problems that make it hard to move
Numbness, weakness, and tingling in his hands
A lot of coughs, colds, and sinus and throat infections
Breathing problems, including pauses in breathing at night, or sleep apnea
Hearing loss and ear infections
Trouble walking and weak muscles
Bowel problems, such as diarrhea
Heart problems, including damaged heart valves
Enlarged liver and spleen
Bone thickening

When a boy's brain is affected, it's likely he'll have:

Trouble thinking and learning by the time he is 2 to 4 years old
Trouble talking
Behavior problems such as a hard time sitting still or aggression

Children with Hunter syndrome are usually cheerful and affectionate, despite the problems this can cause.

Geting a diagnosis

Doctors often have to rule out other diseases first. Your doctor may ask you:

What symptoms have you noticed?
When did you first see them?
Do they come and go?
Does anything make them better? Or worse?
Has anyone in your family had Hunter syndrome or another genetic disease?

If doctors can't find another explanation for your son's symptoms, they'll test for Hunter syndrome by looking for:

High levels of that certain sugar in his urine
How active the "missing" protein is in his blood or skin cells
The abnormal gene

Once doctors are convinced it's Hunter's syndrome, it's a good idea to tell family members about the genetic problem.

If you are a pregnant woman and know you are a carrier of this gene, or if you already have a child with Hunter syndrome, you can find out if the child you are carrying is affected. Talk to your doctor about testing in early pregnancy.

Questions for the doctor

Will his symptoms change over time? If so, how?
What treatments are best for him now? Is there a clinical trial that could help?
Do these treatments have side effects? What can I do about them?
How do we check his progress? Are there new symptoms I should watch for?
How often do we need to see you?
Are there other specialists we should see?
If I have more children, are they likely to have this disease?

Treatment

Early treatment may prevent some long-term damage.

Enzyme replacement therapy may help slow down the course of the disease in boys with milder Hunter syndrome. It replaces the protein that their body does not produce. Enzyme replacement therapy can help improve:

Walking, climbing stairs, and the ability to keep up in general
Movement and stiff joints
Breathing
Growth
Hair and facial features

Enzyme replacement therapy is the first treatment for children whose brains are not affected. It does not slow down the disease in the brain.

Bone marrow and cord blood transplant. These transplants transfer cells into your child's body that can hopefully produce the protein they lack. The new cells are obtained either from a bone marrow donor whose cells match those of your baby, or from stem cells from the cord blood of newborns.

Both of these treatments carry a high risk. They are usually only used when other treatments are not possible. They have also not been shown to help with brain damage.

Research is ongoing to find effective treatments for boys with severe Hunter syndrome.

Treat the symptoms. Because so many different parts of your child's body can be affected, you will likely need to see several doctors to help manage the condition, including:

Cardiologist: cardiologist
Ear, nose and throat specialist
Ophthalmologist
Pulmonologist
Mental health specialist
Neurologist: works with the brain and nerves
Speech therapist

Medications or surgery can relieve some of the complications. Physical therapy can help with joint and movement problems. And occupational therapy can help you make changes at home and at school to make it easier to move around and work. Medications such as melatonin can help you sleep.

Take care of your son

Focus on keeping your son healthy and giving him a chance to live a full and fulfilling life. Involve him in family activities whenever it is safe to do so.

Set the tone for others. Be positive. Keep an open mind towards others; they may not know what to say without upsetting, offending, or embarrassing you. When someone asks about him, be realistic about his condition. Tell us about him as a person - his interests, curiosity and sunny nature. Let them know what their needs and abilities are and how they can help you, if appropriate.
Activity. Start stretching and range of motion exercises early to keep your joints flexible. Ask your physical therapist how to incorporate exercise into the game. Choose large toys that are easy to grab and hold and won't get damaged by chewing.
Encourage friendships. Talk to other children (or their parents) about how to interact with your son. Approach him from the front with your arms outstretched. Give him space at arm's length. It would be nice to remind him to gently touch, not hit. But kids are kids, so prepare him for stares and teasing with role play and humor.
Additional help for learning. Help him learn as much as possible while his brain is working well. If he goes to school, work with the staff to create a personalized learning plan for him. They may be entitled to individual attention in the classroom or assistance with other problems such as hearing problems.
Take care of yourself too. You will be better able to take care of your child if you have people to turn to for help with caregiving tasks. Take a step back and take a break to rest and recharge. Take the time to develop relationships with yourself and the people you love. Remember that the whole family suffers from this disease. A counselor can help sort out feelings.

What to expect

Some boys with less severe Hunter syndrome grow up and live long lives. They will go through puberty like other teenagers and be able to have children. But heart disease and breathing problems can still cause them problems.

Children with severe Hunter syndrome are less likely to reach adulthood. Their brains will slowly shut down and eventually they will need special care to feel comfortable.

Parents of other boys with Hunter syndrome are a great resource for understanding what's going on, sharing their feelings, and getting ideas on how to live with the condition. You can find ways to enjoy the time you spend with your child.

What is Hunter syndrome (MPS II)?