Mucopolysaccharide Diseases

Definition:
Mucopolysaccharide diseases (MPS), also known as lysosomal storage diseases, are rare, life-threatening, progressive metabolic conditions each caused by a shortage of a particular enzyme.

The enzyme deficiency that results from mucopolysaccharide diseases means the body can’t break down (metabolise) certain molecules called GAGs (glycosaminoglycans).

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GAGs are structural molecules that are integral to connective tissues such as cartilage. They accumulate in cells within tiny structures called lysosomes. This leads to dysfunction the cells, resulting in dysfunction of tissues and organs.

There are many different types of MPS including: Hurler; Hunter; Sanfillipo; Morquio; Maroteaus-Lamy and Sly.

Seven distinct clinical types and numerous subtypes of the mucopolysaccharidoses have been identified. Although each mucopolysaccharidosis (MPS) differs clinically, most patients generally experience a period of normal development followed by a decline in physical and/or mental function. (Note: MPS-V and MPS-VIII are no longer in use as designations for any disease.)

Symptoms
Patients with MPS appear normal at birth and usually present with developmental delay in the first year of life. The different types have slight variation in symptoms, which include problems with their eyes, skin, heart, bones and mental retardation.

Hurler syndrome (MPS 1) typifies MPS. It is the most severe form, progresses quickly and normally results in death by the age of 10. The clinical features of Hurler syndrome are:

•Coarse faces, large tongues, male-pattern hairiness and corneal clouding
•Airway problems and glue ear
•Skeletal deformities
•Cardiomyopathy (a problem with the heart muscle)
•Large liver and spleen
•Hernias
•Stiff joins
•Hearing loss
•Developmental delay and retardation

Causes:
MPS is an inherited disease. The majority of types are inherited by autosomal recessive transmission. That means that if both of your parents are carriers, you have a one if four chance of having the disease.

Diagnosis:
Diagnosis often can be made through clinical examination and urine tests (excess mucopolysaccharides are excreted in the urine). Enzyme assays (testing a variety of cells or body fluids in culture for enzyme deficiency) are also used to provide definitive diagnosis of one of the mucopolysaccharidoses. Prenatal diagnosis using amniocentesis and chorionic villus sampling can verify if a fetus either carries a copy of the defective gene or is affected with the disorder. Genetic counseling can help parents who have a family history of the mucopolysaccharidoses determine if they are carrying the mutated gene that causes the disorders.

Treatment:
Currently there is no cure for these disorders. Medical care is directed at treating systemic conditions and improving the person’s quality of life. Physical therapy and daily exercise may delay joint problems and improve the ability to move.

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Changes to the diet will not prevent disease progression, but limiting milk, sugar, and dairy products has helped some individuals experiencing excessive mucus.

Surgery to remove tonsils and adenoids may improve breathing among affected individuals with obstructive airway disorders and sleep apnea. Sleep studies can assess airway status and the possible need for nighttime oxygen. Some patients may require surgical insertion of an endotrachial tube to aid breathing. Surgery can also correct hernias, help drain excessive cerebrospinal fluid from the brain, and free nerves and nerve roots compressed by skeletal and other abnormalities. Corneal transplants may improve vision among patients with significant corneal clouding.

Enzyme replacement therapy (ERT) are currently in use or are being tested. Enzyme replacement therapy has proven useful in reducing non-neurological symptoms and pain. Currently BioMarin Pharmaceutical produces enzyme replacement therapies for MPS type I and VI. In July 2006, the United States Food and Drug Administration approved a synthetic version of I2S produced by Shire Pharmaceuticals Group, called Elaprase, as a treatment for MPS type II (Hunter syndrome).

Bone marrow transplantation (BMT) and umbilical cord blood transplantation (UCBT) have had limited success in treating the mucopolysaccharidoses. Abnormal physical characteristics, except for those affecting the skeleton and eyes, may be improved, but neurologic outcomes have varied. BMT and UCBT are high-risk procedures and are usually performed only after family members receive extensive evaluation and counseling.

 

Genetics:
It is estimated that 1 in 25,000 babies born in the United States will have some form of the mucopolysaccharidoses. It is an autosomal recessive disorder, meaning that only individuals inheriting the defective gene from both parents are affected. (The exception is MPS II, or Hunter syndrome, in which the mother alone passes along the defective gene to a son.) When both people in a couple have the defective gene, each pregnancy carries with it a one in four chance that the child will be affected. The parents and siblings of an affected child may have no sign of the disorder. Unaffected siblings and select relatives of a child with one of the mucopolysaccharidoses may carry

 

 

Disclaimer: This information is not meant to be a substitute for professional medical advise or help. It is always best to consult with a Physician about serious health concerns. This information is in no way intended to diagnose or prescribe remedies.This is purely for educational purpose

Resources:
http://en.wikipedia.org/wiki/Mucopolysaccharidosis

MPS III – Sanfilippo Disease


http://www.bbc.co.uk/health/physical_health/conditions/mucopolysaccharide2.shtml#what_are_mucopolysaccharide_diseases_mps_

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