Mucopolysaccharidoses occur when the body lacks enzymes needed to break down and store complex sugar molecules.
Typically, symptoms include short stature, hairiness, stiff finger joints, and coarseness of the face.
The diagnosis is based on symptoms, a physical examination, and blood tests.
Although a normal life span is possible, some types cause premature death.
Treatment may include lifelong enzyme replacement therapy, and sometimes a bone marrow transplant.
There are different types of inherited disorders Inheritance of Single-Gene Disorders Genes are segments of deoxyribonucleic acid (DNA) that contain the code for a specific protein that functions in one or more types of cells in the body. Chromosomes are made of a very long strand... read more . In many hereditary metabolic disorders, both parents of the affected child carry a copy of the abnormal gene. Because usually two copies of the abnormal gene are necessary for the disorder to occur, usually neither parent has the disorder. Some hereditary metabolic disorders are X-linked X-Linked Recessive Disorders Genes are segments of deoxyribonucleic acid (DNA) that contain the code for a specific protein that functions in one or more types of cells in the body. Chromosomes are made of a very long strand... read more , which means only one copy of the abnormal gene can cause the disorder in boys. (See also Overview of Hereditary Metabolic Disorders Overview of Hereditary Metabolic Disorders Hereditary metabolic disorders are inherited genetic conditions that cause metabolism problems. Heredity is the passing of genes from one generation to the next. Children inherit their parents'... read more .)
Complex sugar molecules called mucopolysaccharides (glycosaminoglycans) are essential parts of many body tissues. In mucopolysaccharidoses, the body lacks enzymes needed to break down (metabolize) and store mucopolysaccharides. As a result, excess mucopolysaccharides enter the blood and are deposited in abnormal locations throughout the body.
Types of mucopolysaccharidosis
There are many types of mucopolysaccharidosis depending on which specific enzyme is missing. The types are classified by Roman numerals and sometimes also given a specific name (for example, Hurler syndrome and Hunter syndrome).
Symptoms of Mucopolysaccharidoses
Different types of mucopolysaccharidosis have slightly different symptoms but, in general, during infancy and childhood, short stature, hairiness, and abnormal development become noticeable. The face may appear heavy with a large head, prominent forehead, short nose, and large lips and tongue. Some types of mucopolysaccharidoses cause intellectual disability Intellectual Disability Intellectual disability is significantly below average intellectual functioning present from birth or early infancy, causing limitations in the ability to conduct normal activities of daily... read more that may worsen over the course of a person's life. In some types, vision or hearing may become impaired. The arteries or heart valves can be affected. Finger joints are often stiff.
Diagnosis of Mucopolysaccharidoses
Prenatal screening tests
Based on symptoms and an examination
Sometimes imaging or other blood tests
Before birth, mucopolysaccharidoses can be diagnosed by using the prenatal screening tests amniocentesis Amniocentesis Prenatal diagnostic testing involves testing the fetus before birth (prenatally) to determine whether the fetus has certain abnormalities, including certain hereditary or spontaneous genetic... read more or chorionic villus sampling Chorionic Villus Sampling Prenatal diagnostic testing involves testing the fetus before birth (prenatally) to determine whether the fetus has certain abnormalities, including certain hereditary or spontaneous genetic... read more .
After birth, a doctor usually bases the diagnosis of mucopolysaccharidoses on the symptoms and a physical examination. The presence of a mucopolysaccharidosis in other family members also suggests the diagnosis. Urine tests may help but are sometimes inaccurate. X-rays may show characteristic bone abnormalities. Mucopolysaccharidoses also are diagnosed by analyzing blood cells. Genetic testing Genetic Screening Genetic screening is used to determine whether a couple is at increased risk of having a baby with a hereditary genetic disorder. Hereditary genetic disorders are disorders of chromosomes or... read more , which is used to determine whether a couple is at increased risk of having a baby with a hereditary genetic disorder, is available.
Other tests are done depending on symptoms. For example, children who have heart problems may undergo the imaging test echocardiography Echocardiography and Other Ultrasound Procedures Ultrasonography uses high-frequency (ultrasound) waves bounced off internal structures to produce a moving image. It uses no x-rays. Ultrasonography of the heart (echocardiography) is one of... read more , and children who have hearing problems may undergo audiometry Testing Worldwide, about half a billion people (almost 8% of the world's population) have hearing loss. More than 10% of people in the United States have some degree of hearing loss that affects their... read more .
Prognosis of Mucopolysaccharidoses
The prognosis depends on the type of mucopolysaccharidosis. A normal life span is possible. Some types, usually those that affect the heart, may cause premature death.
Treatment of Mucopolysaccharidoses
Sometimes bone marrow or stem cell transplantation
Lifelong enzyme replacement therapy is being used to treat some mucopolysaccharidoses and may prevent the disorders from getting worse and reverse some of the complications.
Bone marrow transplantation or stem cell transplantation Stem Cell Transplantation Stem cell transplantation is the removal of stem cells (undifferentiated cells) from a healthy person and their injection into someone who has a serious blood disorder. (See also Overview of... read more may help some people. However, these procedures may result in death or disability, so these treatments remain somewhat controversial.