Mucopolysaccharidosis Type II (MPS II) mainly affects boys and is a type of lysosomal storage disorder.
MPS II is caused by a shortage of the enzyme iduronate-2-sulphatase, leading to the buildup of complex carbohydrates called glycosaminoglycans (GAGs) in various organs and tissues. Symptoms and disease severity can vary, but common features include distinct facial characteristics, an enlarged head, frequent ear infections, and abnormalities like an enlarged liver and spleen. Severe cases usually show symptoms between 18 months and 4 years, with two-thirds experiencing central nervous system involvement, leading to neurological decline and intellectual disability. Other notable features include skeletal issues, hearing loss, heart problems, and respiratory difficulties. Milder cases may exhibit non-central nervous system symptoms in infancy or childhood, with varying severity. Heart disease and hearing loss remain common, but neurologic and motor development can be normal. Unfortunately, there is no cure for MPS II. Treatment focuses on symptom management, including therapies for developmental delays and surgical procedures for heart issues. Enzyme replacement therapy (idursulfase) addresses non-central nervous system complications, and other treatments like bone marrow or stem cell transplants have been attempted, but more research is needed to understand their long-term effectiveness.
MPS II is caused by pathogenic (disease-causing) variants in the IDS gene and exhibits autosomal recessive inheritance. This means that both parents must be carriers to have a 25% chance to have a child with the condition.
Other names for this condition are Hunter syndrome and iduronate 2-sulfatase deficiency.