Hunter syndrome
| Hunter syndrome | |
|---|---|
| Patient with Hunter syndrome | |
| Specialty | Endocrinology |
| Symptoms | Skeletal abnormalities, hearing loss, retinal degeneration, enlarged liver and spleen |
| Complications | Upper airway disease; cardiovascular failure |
| Causes | Defiency of the enzyme iduronate-2-sulfatase |
| Differential diagnosis | Mucopolysaccharidosis type I; other mucopolysaccharidoses |
| Prognosis | In severe cases, death usually occurs by age 15. In attenuated cases, patients may survive into their 50s |
| Frequency | 1 in 100,000 to 150,000 male births |
Hunter syndrome, or mucopolysaccharidosis type II (MPS II), is a rare inherited lysosomal storage disease in which large sugar molecules called glycosaminoglycans (or GAGs or mucopolysaccharides) build up in body tissues. Hunter syndrome is caused by a deficiency of the lysosomal enzyme iduronate-2-sulfatase (I2S). The lack of this enzyme causes heparan sulfate and dermatan sulfate to accumulate in all body tissues. Hunter syndrome is the only MPS syndrome to exhibit X-linked recessive inheritance.
The symptoms of Hunter syndrome are comparable to those of MPS I. It causes abnormalities in many organs, including the skeleton, heart, and respiratory system. In severe cases, this leads to death during the teenage years. Unlike MPS I, corneal clouding is not associated with this disease.