Mucopolysaccharidosis Type VI

Mucopolysaccharidosis Type VI – General Information

Mucopolysaccharidoses or MPS (also known as Maroteaux-Lamy syndrome) are a group of inherited disorders. They result from the deficiency of the lysosomal enzymes, enzymes that are required for the glycosaminoglycan (GAG) catabolism. Glycosaminoglycans which are important factors of the connective tissues, are long chains of complex carbohydrates that are linked to the proteins. Because of the situation of the GAGs in the connective tissue, the site of pathology includes the heart valves, the skeleton and other organs or tissues that contain connective tissue stroma. From the lysosomal accumulation of GAGs result the features of the Mucopolysaccharidoses that include: corneal clouding, organomegaly, coarse facies, dysostosis multiplex, hernias, joint stiffness, short stature and in some cases even mental retardation.

The pattern that results from the GAG degradation and the enzymatic deficiency determine the phenotype of each disorder. Visceral manifestations are associated with chondroitin sulfate, dermatan and keratin which are degradation products, while the mental deficiency is associated with the degradation of the heparan sulfate. This medical condition is an autosomal recessive trait that can be inherited that results from the deficiency of N acetylgalactosamine 4 (arylsulfatase B) and the lysosomal accumulation of dermatensulfate and it is characterized not by mental deficiency, but by somatic features. Mucopolysaccharidosis Type VI is also characterized by the connective-tissue organ that results from the continuous deposit of dermatan sulfate in the heart valves, spleen, skeleton, liver and cornea. Studies have outlined that in the affected tissues that engorged lysosomes are present. This medical condition is usually diagnosed in childhood as organomegaly, enlarged tongue; joint stiffness and corneal clouding are obvious.

Mucopolysaccharidosis Type VI – Symptoms

Mucopolysaccharidosis Type VI has many symptoms that affect different body parts, a part of these symptoms can also be found in other medical conditions, while the other part are specific for this disease. A patient may present only one or two of these symptoms, and they can be very mild. The most common symptoms of this disorder (Mucopolysaccharidosis Type VI) are:

• Short stature – children may stop completely from growing at the age of six or maximum eight years of age.
• Coarsening of facial features – is produced gradually and includes: flat nasal bridge, broad nose, large head, short neck, prominent eyes and thickened tongue and lips.
• Cloudy cornea ( the cornea is an outer cover of the eye)
• Ear infections, sinus infection and pneumonia are very frequent
• Noisy breathing and even shortness of breath, as the trachea becomes narrow in time.
• Heart murmur
• Bulged abdomen – which is caused by the organomegaly (the enlargement of the spleen or liver)
• Navel or groin hernias
• Stiffness of joints that include elbows, shoulders, hands, hips and knees
• Changes in the bone’s shapes
• Compression of the spinal cord
• Dental problems
• Excess mucus secretions
• Heart problems
• Thick and tight skin

Mucopolysaccharidosis Type VI does not affect the intelligence, but the patients who suffer from this disease may develop hydrocephalus, in time. Hydrocephalus is dangerous pressure of the sac fluid which encloses the brain that can lead to headaches, changes in the behavior and in extreme cases can damage the brain irremediably.

Mucopolysaccharidosis Type VI – Treatment

The diagnosis of this disorder is in most of the cases delayed; this is due to the fact that Mucopolysaccharidosis Type VI can only be diagnosed using laboratory tests. One of the tests is urine GAG analyses – this test measures the amount of glycosaminoglycans (GAGs) in the urine-, as people which suffer from this disease usually have a high level of GAGs. Another test measures the amount of arylsulfatase B (ASB) enzyme in the blood or skin cells, as people who have this medical condition usually have a low quantity of this enzyme. Mucopolysaccharidosis Type VI cannot be cured totally, but there are studies made to help improve the quality of life, to prevent the permanent tissue damage and to slow down the progression of the disease. The treatments which are based on the symptoms have a big role in maintaining the quality of life and in some cases can prevent the appearance of irremediable damage such as: blindness, deafness or paralysis.

One of the important approaches of treating Mucopolysaccharidosis Type VI is hematopoietic stem cell transplant also known as HSCT. A person with this disorder is transplanted with cells from a healthy person. Once these transplanted cells come in contact with the sick organism they produce small amounts of the deficient enzyme, which the patients do not have at all or do not have enough. Using this method includes assuming the medical risks associated with this procedure. Another approach of treating this medical condition is the enzyme replacement therapy also known as ERT. This therapy consists in the replacement of the missing enzyme through intravenous infusions done regularly.

There is an increased mortality in patients who have this medical condition, which is due to the combination of restrictive lung disease, respiratory infections and advanced valvar heart disease. Patients who have Mucopolysaccharidosis Type VI are usually not allowed to have a general anesthesia, not even when they need an endotracheal intubation. There was general anesthesia made on a patient as he had a neurosurgical emergency operation, and even if in the first hours he had no complications, he developed pulmonary edema and consecutive bilateral pneumonia in the first days after the surgery. This disease predisposes patients to respiratory complications. The changes in one’s diet cannot prevent the evolution of this disorder, but renouncing to milk, sugar, dairy products can help some of the patients who have excessive mucus. A way to improve breathing for those who have obstructive airways disorders and sleep apnea from the Mucopolysaccharidosis Type VI is the surgery of removing tonsils and adenoids, surgery can also correct hernias, free nerves and nerve roots that can be affected by compression of the skeleton and can help to the drainage of the cerebrospinal fluid from the brain. A bone marrow transplant can be affective for the patients who suffer from this disorder, but for the transplant to be effective it is need to be done before the patient starts growing and developing.