Hunter Syndrome is one of several hereditary metabolic conditions known collectively as lysosomal storage disorders. These are genetically distinct diseases that result from a deficiency of a particular enzyme.
Hunter syndrome, also known as mucopolysaccharidosis II or MPS II, is caused by an inherited deficiency in the enzyme iduronate-2-sulfatase (or I2S). Lack of this enzyme affects the body’s ability to break down and recycle cellular waste.
Hunter syndrome affects approximately 1 in every 155,000 people.
It primarily affects boys, because it is as an X chromosome-linked recessive disease, Boys have only 1 copy of the X chromosome, while girls have 2 copies. Women can carry one defective Hunter syndrome gene and pass it on without being affected themselves.
Symptoms are usually not prominent at birth, but as individuals affected with Hunter syndrome grow older, physical manifestations become more apparent.
Because Hunter syndrome is rare and its symptoms are common in children — frequent ear infections, chronic runny nose, hernias — it’s often misdiagnosed. People often receive diagnosis after the onset of more serious symptoms, such as cardiac and respiratory problems.
Getting an early diagnosis is important: treatment can head-off the progression of the Hunter syndrome. Current treatment is an enzyme replacement therapy ( ELAPRASE ).