Hunter Syndrome: Causes and Symptoms

What is Hunter syndrome?

Hunter syndrome (also called mucopolysaccharidosis, type 2 or MPS II) is a genetic condition in which the body creates too little iduronate 2-sulfatase enzyme (an enzyme that helps the body break down certain types of sugar). Hunter syndrome typically affects biological males (people assigned male at birth). There are 2 forms of disease: early and slowly progressive forms. The difference between the two forms depends on when symptoms first begin and how quickly they progress.

What are the symptoms of Hunter syndrome?

• Short stature (short height)
• Hepatosplenomegaly (large liver and spleen)
• Joint problems
• Prominent (larger or more noticeable) facial features
• Frequent ear infections
• Hearing loss
• Skeletal problems (conditions that affect the bones)
• Umbilical hernia (when the intestines push through a weak spot in the abdomen, or belly area, near the belly button)
• Developmental delay in some people

What causes Hunter syndrome?

Hunter syndrome is caused by changes in the IDS gene. Genes are the instructions that tell our bodies how to develop and function. The job of the IDS gene is to create the iduronate 2-sulfatase enzyme. People with certain mutations (changes or misspellings) in the IDS gene create too little or no iduronate 2-sulfatase enzyme.

The IDS gene is on the X-chromosome (one of 2 sex chromosomes, or pieces of genetic material called DNA, in the body). It is passed down in an x- linked inheritance pattern (genetic conditions or traits that are passed down from parent to child through the X chromosome).

Rev. 6/2022. Mass General for Children and Massachusetts General Hospital do not endorse any of the brands listed on this handout. This handout is intended to provide health information so you can be better informed. It is not a substitute for medical advice and should not be used to treat any medical conditions.