What is Hunter syndrome?

Hunter syndrome is a very rare, inherited genetic disorder caused by a missing or malfunctioning enzyme. In Hunter syndrome, the body doesn’t have enough of the enzyme iduronate 2-sulfatase. This enzyme’s job is to break down certain complex molecules, and without enough of this enzyme, the molecules build up in harmful amounts.

The buildup of massive amounts of these harmful substances eventually causes permanent, progressive damage affecting appearance, mental development, organ function and physical abilities.

Hunter syndrome is far more common in boys. The condition is one type of a group of inherited metabolic disorders called mucopolysaccharidoses (MPSs). Hunter syndrome is also known as MPS II.

There’s no cure for Hunter syndrome. Treatment involves managing symptoms and complications.