What is Hunter syndrome?

Hunter syndrome, also known as mucopolysaccharidosis type II (MPS II) is a rare genetic disease almost exclusively affecting boys. Hunter syndrome is one of a number of lysosomal storage diseases (LSDs). It is estimated that the condition is present in 1 in 162 000 live births.

Hunter syndrome can affect any part of the body and causes a number of signs and symptoms. In the majority of people with Hunter syndrome, the signs and symptoms present between the ages of 2 and 4 years.

Many of the signs and symptoms are common childhood complaints, and it is the combination of them that may indicate Hunter syndrome. The symptoms of Hunter syndrome are different in each person, so there is no single typical patient experience.

Learn more about the signs and symptoms of Hunter syndrome

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What causes Hunter syndrome?

Hunter syndrome is one of a number of lysosomal storage diseases (LSDs). LSDs are conditions in which cells are unable to properly break down certain molecules. In Hunter syndrome, an enzyme called iduronate-2-sulfatase (I2S) is deficient or sometimes completely absent.

In a healthy cell, I2S breaks down particular molecules, known as glycosaminoglycans (GAGs).  These molecules were previously called mucopolysaccharides, which is why Hunter syndrome is also known as mucopolysaccharidosis type II (MPS II).

If I2S is deficient or absent, GAGs build up, which prevents the cell from functioning properly. All healthy cells (except red blood cells) make the I2S enzyme, so its deficiency can affect any part of the body. This is why Hunter syndrome may have symptoms in several organs, and is called a multisystemic disease.

 

Aiden and AJ

Aiden was born a beautiful, healthy baby boy but he had frequent ear infections that we were told were typical. He had two sets of tubes put in his ears and then adenoids removed, when he was a year and a half old. He got colds a lot.

When he was about 2 years old, I noticed Aiden had speech delay. So, I got him into early intervention and his paediatrician suggested that it’s just something that kids go through, he’ll catch up. – Toni Ann, mother of Aiden and AJ

View Aiden and AJ's story

Hunter and Kingston

I have three sons. Hunter is my oldest, he’s 7 years old. He’s a livewire. From the very beginning he was sick all the time. We were in the hospital or the doctor’s office every month with high fevers because of ear infections. He had an umbilical hernia that never went away. I got pregnant with Kingston, when he was 6 months old. By that time, Hunter was just always sick. – Brittany, mother of Hunter and Kingston

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Silas

My husband and I felt we were the luckiest people on earth when we actually held our little boy Silas in our arms. When Silas was around 6 months old, we noticed that the back of his head was becoming flatter and that he couldn’t hold his head up properly.

Silas always cried when he was laid down to play on his stomach. We saw an osteopath who gave us exercises that Silas didn’t like at all. The osteopath said she thought that Silas was maybe a bit ‘lazy’ as he didn’t invest much effort in trying to reach toys or in crawling. – Natalie, mother of Silas

View Silas' story

Learn more about the early signs and symptoms that each of these patients experienced

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Talk to your doctor

In Hunter syndrome, glycosaminoglycans (GAGs) build up, which leads to parts of the body not functioning properly. As the GAGs accumulate over time, the signs and symptoms of Hunter syndrome progress.

The progressive nature of the condition means that early diagnosis is essential, so that disease management can begin as soon as possible.

Since Hunter syndrome often affects several different parts of the body, it is likely that a number of specialist healthcare professionals will be involved in your child’s care to help manage the range of symptoms.

If you think that your child shows symptoms of Hunter syndrome, speak to your doctor.

If you have recently received a diagnosis of Hunter syndrome, it can be hard to know what questions to ask, and to keep track of all the information from your appointments with healthcare professionals. The Discussing Hunter syndrome with your child’s doctor is a resource that may help you talk to your doctor about your child’s symptoms. The guide highlights the key signs that should prompt suspicion of Hunter syndrome.

Discussing Hunter syndrome with your child’s doctor is a resource that may help you talk to your doctor about your child’s symptoms.

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