Hunter syndrome, or mucopolysaccharidosis type II (MPS II), is a rare genetic disorder in which large sugar molecules called glycosaminoglycans (or GAGs or mucopolysaccharides) build up in body tissues. It is a form of lysosomal storage disease. 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 teenaged years. Unlike MPS I, corneal clouding is not associated with this disease. Signs and symptoms
Hunter syndrome may present with a wide variety of phenotypes. It has traditionally been categorized as either "mild" or "severe" depending on the presence of central nervous system symptoms, but this is an oversimplification. Patients with "attenuated" or "mild" forms of the disease may still have significant health issues. For severely affected patients, the clinical course is relatively predictable; patients will normally die at an early age. For those with milder forms of the disease,  a wider variety of outcomes exist. Many live into their 20s and 30s, but some may have near-normal life expectancies. Cardiac and respiratory abnormalities are the usual cause of death for patients with milder forms of the disease.The symptoms of Hunter syndrome (MPS II) are generally not apparent at birth.
A phase II/III clinical trial began in 2014.In 2017, a 44-year-old  patient with MPS II was treated with gene therapy in an attempt to prevent further damage by the disease. This is the first case of gene therapy being used in vivo in humans. The study was extended to six patients in 2018. Society
On 24 July 2004, Andrew Wragg, 38, of Worthing, West Sussex, England, suffocated his 10-year-old son Jacob with a pillow, because of the boys disabilities related to MPS II. A military security specialist, Wragg also claimed that he was under stress after returning from the war in Iraq. He denied murdering Jacob, but pleaded guilty to manslaughter by reason of diminished capacity. Mrs Justice Anne Rafferty called the case "exceptional", gave Wragg a two-year prison sentence for manslaughter, then suspended his sentence for two years. Rafferty said  "nothing [was] to be gained" from sending Wragg to prison for the crime. See also
Hurler syndrome (MPS I)
Sanfilippo syndrome (MPS III)
Morquio syndrome (MPS IV)
Prenatal testing
Genetic counseling

References
External links
 Media related to Hunter syndrome at Wikimedia Commons
GeneReview/NIH/UW entry on Mucopolysaccharidosis Type II