BACK TOTOP Browse A-ZSearchBrowse A-ZABCDEFGHIJKLMNOPQRSTUVWXYZ0-9 E-mail FormEmail ResultsName:Email address:Recipients Name:Recipients address:Message: Print-FriendlyBookmarksbookmarks-menuMucopolysaccharidosis type IIMPS II; Hunter syndrome; Lysosomal storage disease - mucopolysaccharidosis type II; Iduronate 2-sulfatase deficiency; I2S deficiencyMucopolysaccharidosis type II (MPS II) is a rare disease in which the body is missing or does not have enough of an enzyme needed to break down long chains of sugar molecules. These chains of molecules are called glycosaminoglycans (formerly called mucopolysaccharides). As a result, the molecules build up in different parts of the body and cause various health problems.EnzymeEnzymes are complex proteins that cause a specific chemical change. For example, they can help break down the foods we eat so the body can use them....Read Article Now Book Mark Article The condition belongs to a group of diseases called mucopolysaccharidoses (MPSs). MPS II is also known as Hunter syndrome.MucopolysaccharidosesMucopolysaccharidoses (MPSs) are a group of rare diseases in which the body is missing or does not have enough of an enzyme needed to break down long...Read Article Now Book Mark Article There are several other types of MPSs, including:MPS I (Hurler syndrome; Hurler-Scheie syndrome; Scheie syndrome) MPS IMucopolysaccharidosis type I (MPS I) is a rare disease in which the body is missing or does not have enough of an enzyme needed to break down long ch...Read Article Now Book Mark Article MPS III (Sanfilippo syndrome) MPS IIIMucopolysaccharidosis type III (MPS III) is a rare disease in which the body is missing or does not have enough of certain enzymes needed to break do...Read Article Now Book Mark Article MPS IV (Morquio syndrome) MPS IVMucopolysaccharidosis type IV (MPS IV) is a rare disease in which the body is missing or does not have enough of an enzyme needed to break down long ...Read Article Now Book Mark Article Causes MPS II is a genetic disorder. This means it can be passed down through families. The affected gene is on the X chromosome. Boys are most often affected because they have only one X chromosome, which they inherit from their mothers. Their mothers do not have symptoms of the disease because although they carry one nonworking copy of the gene, they also have a second copy of the X chromosome.MPS II is caused by a lack of the enzyme iduronate sulfatase. Without this enzyme, chains of sugar molecules build up in various body tissues, causing damage.The early-onset, severe form of the disease begins shortly after age 2. A late-onset, mild form causes less severe symptoms to appear later in life. Symptoms In the early-onset, severe form, symptoms include:Aggressive behavior Hyperactivity HyperactivityHyperactivity means having increased movement, impulsive actions, a shorter attention span, and being easily distracted.Read Article Now Book Mark Article Mental function gets worse over time Severe intellectual disability Intellectual disabilityIntellectual disability is a condition diagnosed before age 18 that includes below-average intellectual function and a lack of skills necessary for d...Read Article Now Book Mark Article Jerky body movements In the late (mild) form, there can be mild to no mental deficiency.In both forms, symptoms include:Carpal tunnel syndrome Carpal tunnel syndromeCarpal tunnel syndrome is a condition in which there is excessive pressure on the median nerve at the wrist. This is the nerve that allows feeling a...Read Article Now Book Mark Article Coarse features of the face Deafness (gets worse over time) DeafnessHearing loss is being partly or totally unable to hear sound in one or both ears.Read Article Now Book Mark Article Increased hair growth Joint stiffness Large headLarge headIncreased head circumference is when the measured distance around the widest part of the skull is larger than expected for the child's age and backgr...Read Article Now Book Mark Article Exams and Tests A physical exam and tests may show:Abnormal retina (back of the eye) RetinaThe retina is the light-sensitive layer of tissue at the back of the eyeball. Images that come through the eye's lens are focused on the retina. Th...Read Article Now Book Mark Article Decreased iduronate sulfatase enzyme in blood serum or cells Heart murmur and leaky heart valves Heart murmurA heart murmur is a blowing, whooshing, or rasping sound heard during a heartbeat. The sound is caused by turbulent (rough) blood flow through the h...Read Article Now Book Mark Article Enlarged liver Enlarged liverEnlarged liver refers to swelling of the liver beyond its normal size. Hepatomegaly is another word to describe this problem. If both the liver and ...Read Article Now Book Mark Article Enlarged spleen Enlarged spleenSplenomegaly is a larger-than-normal spleen. The spleen is an organ in the upper left part of the belly.Read Article Now Book Mark Article Hernia in the groin Hernia in the groinA hernia occurs when the contents of the abdomen push through a weak point or tear in the muscle wall of the belly. This layer of muscle holds the a...Read Article Now Book Mark Article Joint contractures (from joint stiffness)ContracturesA contracture develops when normally stretchy (elastic) tissues are replaced by nonstretchy (inelastic) fiber-like tissue. This tissue makes it hard...Read Article Now Book Mark Article Tests may include:Enzyme study Genetic testing for a change in the iduronate sulfatase gene Urine test for heparan sulfate and dermatan sulfate Treatment The medicine called idursulfase (Elaprase), which replaces the enzyme iduronate sulfatase may be recommended. It is given through a vein (IV, intravenously). Talk to your health care provider for more information.Bone marrow transplant has been tried for the early-onset form, but the results can vary.Bone marrow transplantA bone marrow transplant is a procedure to replace damaged or diseased bone marrow with healthy bone marrow stem cells. Bone marrow is the soft, fatt...Read Article Now Book Mark Article Each health problem caused by this disease should be treated separately. Support Groups More information and support for people with MPS II and their families can be found at:National MPS Society -- mpssociety.org/ National Organization for Rare Disorders -- rarediseases.org/rare-diseases/mucopolysaccharidosis-type-ii-2/ NIH Genetic and Rare Diseases Information Center -- rarediseases.info.nih.gov/diseases/6675/mucopolysaccharidosis-type-ii Outlook (Prognosis) People with the early-onset (severe) form usually live for 10 to 20 years. People with the late-onset (mild) form usually live 20 to 60 years. Possible Complications These complications may occur:Airway obstruction Airway obstructionBlockage of the upper airway occurs when the upper breathing passages become narrowed or blocked, making it hard to breathe. Areas in the upper airw...Read Article Now Book Mark Article Carpal tunnel syndrome Hearing loss that gets worse over time Loss of ability to complete daily living activities Joint stiffness that leads to contractures Mental function that gets worse over time When to Contact a Medical Professional Contact your provider if:You or your child has a group of these symptoms You know you are a genetic carrier and are considering having children Prevention Genetic counseling is recommended for couples who want to have children and who have a family history of MPS II. Prenatal testing is available. Carrier testing for female relatives of affected males is also available.Genetic counselingGenetics is the study of heredity, the process of a parent passing certain genes on to their children. A person's appearance, such as height, hair co...Read Article Now Book Mark Article Open ReferencesReferencesKumar V, Abbas AK, Aster JC. Genetic disorders. In: Kumar V, Abbas AK, Aster JC, eds. Robbins & Cotran Pathologic Basis of Disease. 10th ed. Philadelphia, PA: Elsevier; 2021:chap 5.Lampe C. Mucopolysaccharidoses. In: Kliegman RM, St. Geme JW, Blum NJ, et al, eds. Nelson Textbook of Pediatrics. 22nd ed. Philadelphia, PA: Elsevier; 2025:chap 109.Pyeritz RE. Inherited diseases of connective tissue. In: Goldman L, Cooney KA, eds. Goldman-Cecil Medicine. 27th ed. Philadelphia, PA: Elsevier; 2024:chap 239.Turnpenny PD, Ellard S, Cleaver R. Inborn errors of metabolism. In: Turnpenny PD, Ellard S, Cleaver R, eds. Emery's Elements of Medical Genetics and Genomics.16th ed. Philadelphia, PA: Elsevier; 2022:chap 18.AllVideoImagesTogRelated Information Chromosome(Special Topic)Enzyme(Special Topic)Mucopolysaccharides(Special Topic)Intellectual disability(Condition)Spasticity(Symptoms)Breathing difficulty(Symptoms) Review Date: 4/8/2025 Reviewed By: Anna C. Edens Hurst, MD, MS, Associate Professor in Medical Genetics, The University of Alabama at Birmingham, Birmingham, AL. Review provided by VeriMed Healthcare Network. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team. The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed medical professional should be consulted for diagnosis and treatment of any and all medical conditions. Links to other sites are provided for information only -- they do not constitute endorsements of those other sites. No warranty of any kind, either expressed or implied, is made as to the accuracy, reliability, timeliness, or correctness of any translations made by a third-party service of the information provided herein into any other language. © 1997- A.D.A.M., a business unit of Ebix, Inc. Any duplication or distribution of the information contained herein is strictly prohibited. © 1997- All rights reserved. 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Mucopolysaccharidosis type IIMPS II; Hunter syndrome; Lysosomal storage disease - mucopolysaccharidosis type II; Iduronate 2-sulfatase deficiency; I2S deficiencyMucopolysaccharidosis type II (MPS II) is a rare disease in which the body is missing or does not have enough of an enzyme needed to break down long chains of sugar molecules. These chains of molecules are called glycosaminoglycans (formerly called mucopolysaccharides). As a result, the molecules build up in different parts of the body and cause various health problems.EnzymeEnzymes are complex proteins that cause a specific chemical change. For example, they can help break down the foods we eat so the body can use them....Read Article Now Book Mark Article The condition belongs to a group of diseases called mucopolysaccharidoses (MPSs). MPS II is also known as Hunter syndrome.MucopolysaccharidosesMucopolysaccharidoses (MPSs) are a group of rare diseases in which the body is missing or does not have enough of an enzyme needed to break down long...Read Article Now Book Mark Article There are several other types of MPSs, including:MPS I (Hurler syndrome; Hurler-Scheie syndrome; Scheie syndrome) MPS IMucopolysaccharidosis type I (MPS I) is a rare disease in which the body is missing or does not have enough of an enzyme needed to break down long ch...Read Article Now Book Mark Article MPS III (Sanfilippo syndrome) MPS IIIMucopolysaccharidosis type III (MPS III) is a rare disease in which the body is missing or does not have enough of certain enzymes needed to break do...Read Article Now Book Mark Article MPS IV (Morquio syndrome) MPS IVMucopolysaccharidosis type IV (MPS IV) is a rare disease in which the body is missing or does not have enough of an enzyme needed to break down long ...Read Article Now Book Mark Article Causes MPS II is a genetic disorder. This means it can be passed down through families. The affected gene is on the X chromosome. Boys are most often affected because they have only one X chromosome, which they inherit from their mothers. Their mothers do not have symptoms of the disease because although they carry one nonworking copy of the gene, they also have a second copy of the X chromosome.MPS II is caused by a lack of the enzyme iduronate sulfatase. Without this enzyme, chains of sugar molecules build up in various body tissues, causing damage.The early-onset, severe form of the disease begins shortly after age 2. A late-onset, mild form causes less severe symptoms to appear later in life. Symptoms In the early-onset, severe form, symptoms include:Aggressive behavior Hyperactivity HyperactivityHyperactivity means having increased movement, impulsive actions, a shorter attention span, and being easily distracted.Read Article Now Book Mark Article Mental function gets worse over time Severe intellectual disability Intellectual disabilityIntellectual disability is a condition diagnosed before age 18 that includes below-average intellectual function and a lack of skills necessary for d...Read Article Now Book Mark Article Jerky body movements In the late (mild) form, there can be mild to no mental deficiency.In both forms, symptoms include:Carpal tunnel syndrome Carpal tunnel syndromeCarpal tunnel syndrome is a condition in which there is excessive pressure on the median nerve at the wrist. This is the nerve that allows feeling a...Read Article Now Book Mark Article Coarse features of the face Deafness (gets worse over time) DeafnessHearing loss is being partly or totally unable to hear sound in one or both ears.Read Article Now Book Mark Article Increased hair growth Joint stiffness Large headLarge headIncreased head circumference is when the measured distance around the widest part of the skull is larger than expected for the child's age and backgr...Read Article Now Book Mark Article Exams and Tests A physical exam and tests may show:Abnormal retina (back of the eye) RetinaThe retina is the light-sensitive layer of tissue at the back of the eyeball. Images that come through the eye's lens are focused on the retina. Th...Read Article Now Book Mark Article Decreased iduronate sulfatase enzyme in blood serum or cells Heart murmur and leaky heart valves Heart murmurA heart murmur is a blowing, whooshing, or rasping sound heard during a heartbeat. The sound is caused by turbulent (rough) blood flow through the h...Read Article Now Book Mark Article Enlarged liver Enlarged liverEnlarged liver refers to swelling of the liver beyond its normal size. Hepatomegaly is another word to describe this problem. If both the liver and ...Read Article Now Book Mark Article Enlarged spleen Enlarged spleenSplenomegaly is a larger-than-normal spleen. The spleen is an organ in the upper left part of the belly.Read Article Now Book Mark Article Hernia in the groin Hernia in the groinA hernia occurs when the contents of the abdomen push through a weak point or tear in the muscle wall of the belly. This layer of muscle holds the a...Read Article Now Book Mark Article Joint contractures (from joint stiffness)ContracturesA contracture develops when normally stretchy (elastic) tissues are replaced by nonstretchy (inelastic) fiber-like tissue. This tissue makes it hard...Read Article Now Book Mark Article Tests may include:Enzyme study Genetic testing for a change in the iduronate sulfatase gene Urine test for heparan sulfate and dermatan sulfate Treatment The medicine called idursulfase (Elaprase), which replaces the enzyme iduronate sulfatase may be recommended. It is given through a vein (IV, intravenously). Talk to your health care provider for more information.Bone marrow transplant has been tried for the early-onset form, but the results can vary.Bone marrow transplantA bone marrow transplant is a procedure to replace damaged or diseased bone marrow with healthy bone marrow stem cells. Bone marrow is the soft, fatt...Read Article Now Book Mark Article Each health problem caused by this disease should be treated separately. Support Groups More information and support for people with MPS II and their families can be found at:National MPS Society -- mpssociety.org/ National Organization for Rare Disorders -- rarediseases.org/rare-diseases/mucopolysaccharidosis-type-ii-2/ NIH Genetic and Rare Diseases Information Center -- rarediseases.info.nih.gov/diseases/6675/mucopolysaccharidosis-type-ii Outlook (Prognosis) People with the early-onset (severe) form usually live for 10 to 20 years. People with the late-onset (mild) form usually live 20 to 60 years. Possible Complications These complications may occur:Airway obstruction Airway obstructionBlockage of the upper airway occurs when the upper breathing passages become narrowed or blocked, making it hard to breathe. Areas in the upper airw...Read Article Now Book Mark Article Carpal tunnel syndrome Hearing loss that gets worse over time Loss of ability to complete daily living activities Joint stiffness that leads to contractures Mental function that gets worse over time When to Contact a Medical Professional Contact your provider if:You or your child has a group of these symptoms You know you are a genetic carrier and are considering having children Prevention Genetic counseling is recommended for couples who want to have children and who have a family history of MPS II. Prenatal testing is available. Carrier testing for female relatives of affected males is also available.Genetic counselingGenetics is the study of heredity, the process of a parent passing certain genes on to their children. A person's appearance, such as height, hair co...Read Article Now Book Mark Article Open ReferencesReferencesKumar V, Abbas AK, Aster JC. Genetic disorders. In: Kumar V, Abbas AK, Aster JC, eds. Robbins & Cotran Pathologic Basis of Disease. 10th ed. Philadelphia, PA: Elsevier; 2021:chap 5.Lampe C. Mucopolysaccharidoses. In: Kliegman RM, St. Geme JW, Blum NJ, et al, eds. Nelson Textbook of Pediatrics. 22nd ed. Philadelphia, PA: Elsevier; 2025:chap 109.Pyeritz RE. Inherited diseases of connective tissue. In: Goldman L, Cooney KA, eds. Goldman-Cecil Medicine. 27th ed. Philadelphia, PA: Elsevier; 2024:chap 239.Turnpenny PD, Ellard S, Cleaver R. Inborn errors of metabolism. In: Turnpenny PD, Ellard S, Cleaver R, eds. Emery's Elements of Medical Genetics and Genomics.16th ed. Philadelphia, PA: Elsevier; 2022:chap 18.
