What is Hunter syndrome? Also known as MPS II

Hunter syndrome or Mucopolysaccharidosis II (MPS II) is an inherited disorder of carbohydrate metabolism that occurs almost exclusively in males. It is characterized by distinctive facial features, a large head,  hydrocephalus, enlargement of the liver and spleen (hepatosplenomegaly), umbilical or inguinal hernia, and hearing loss. Individuals with this condition may additionally have joint deformities and heart abnormalities involving the valves. MPS II is caused by mutations in the IDS gene and is inherited in an X-linked manner.

There is a wide range in severity of symptoms present in individuals with MPS II. Previously, MPS II was classified as severe and attenuated based on severity. More recently, the terms slowly progressive and early progressive have been suggested. While both types affect many different parts of the body, people with the severe type also experience a decline in intellectual function and a more rapid disease progression. The life expectancy for people with the severe type is 10 to 20 years. Individuals with the less severe type typically live into adulthood and intelligence is not affected. Treatment is focused on managing the signs and symptoms present in each individual.

This video provides an overview of Hunter syndrome, or mucopolysaccharidosis II (MPS II) — a serious genetic disorder that primarily affects males. In Hunter syndrome, GAGs build up in cells throughout the body due to the enzyme iduronate-2-sulfatase (I2S) not working properly or missing altogether. This buildup interferes with the way certain cells and organs in the body function and leads to a number of serious symptoms.