Mucopolysaccharidosis

Mucopolysaccharidosis are a group of metabolic disorders caused by the absence or malfunctioning of lysosomal enzymes needed to break down molecules called glycosaminoglycans (GAGs).

Causes of Mucopolysaccharidosis #

• Most mucopolysaccharidoses are autosomal recessive disorders, meaning that only individuals inheriting the defective gene from both parents are affected.

• 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 the recessive gene and could pass it to their own children.

Symptoms of Mucopolysaccharidosis #

• The mucopolysaccharidoses share many clinical features but have varying degrees of severity.

• These features may not be apparent at birth but progress as storage of GAGs affects bone, skeletal structure, connective tissues, and organs.

• Neurological complications may include damage to neurons (which send and receive signals throughout the body) as well as pain and impaired motor function.

• This results from compression of nerves or nerve roots in the spinal cord or in the peripheral nervous system, the part of the nervous system that connects the brain and spinal cord to sensory organs such as the eyes and to other organs, muscles, and tissues throughout the body.

• Physical symptoms generally include coarse or rough facial features (including a flat nasal bridge, thick lips, and enlarged mouth and tongue), short stature with disproportionately short trunk (dwarfism), dysplasia (abnormal bone size and/or shape) and other skeletal irregularities, thickened skin, enlarged organs such as liver (hepatomegaly) or spleen (splenomegaly), hernias, and excessive body hair growth.

• Short and often claw-like hands, progressive joint stiffness, and carpal tunnel syndrome can restrict hand mobility and function.

Diagnosis of Mucopolysaccharidosis #

• 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.

Treatment of Mucopolysaccharidosis #

• 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.

• 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 has proven useful in reducing non-neurological symptoms and pain.