Hunter syndrome, also known as mucopolysaccharidosis II (MPS II) is a rare, progressive genetic disorder. It predominantly affects males, occurring in approximately 1 in 162,000 live births.1
Hunter syndrome is one of a number of lysosomal storage diseases (LSDs), in which molecules build up in the body. In Hunter syndrome specifically, glycosaminoglycans (GAGs) accumulate abnormally in the body.2
Hunter syndrome is caused by a deficiency or absence of the I2S enzyme.3 Without I2S, GAGs accumulate in the lysosomes, and in Hunter syndrome patients, the progressive build-up interferes with cell functions across all organ systems. The multisystemic disease is associated with many signs and symptoms, which lie on a spectrum from non-neuronopathic (somatic) symptoms to neuronopathic (cognitive) symptoms. Almost 7 out of 10 patients with Hunter syndrome have neuronopathic involvement.3,4
Initial signs of GAG accumulation in Hunter syndrome patients occur from ages 2 to 4 years: hernia, otitis media, and enlarged adenoids/tonsils (managed by adenoidectomy/tonsillectomy). The clinical management of Hunter syndrome patients is continual, symptoms are progressive and multisystemic, and the median life expectancy for patients is 13.4 years.3,5,6

