What Are the Types and Symptoms of Mucopolysaccharidosis?
Due to the abnormal accumulation of mucopolysaccharides, some metabolic disorders can be caused and these are known as mucopolysaccharidosis. The mucopolysaccharides are also known as glycosaminoglycans. These are the long and linear polysaccharides that are made up of repeating sequences of disaccharide units. This means there are two sugar units used in the creation of the mucopolysaccharides.
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One of the two sugar units is amino sugar and the other is uronic sugar. An exception to this pattern is seen in keratan, where the uronic sugar constituent is replaced by galactose. In this article, students are going to learn more about mucopolysaccharides examples and other details.
Mucopolysaccharides Uses
On the basis of the basic core structure assigned to the disaccharides, they can be classified into four different groups. These are known as Heparin sulfate or Heparin, Hyaluronic acid, Keratan sulfate, and dermatan sulfate or chondroitin.
One primary mucopolysaccharides function can be seen in the form of Heparin. This group is mostly stored in the Mast cells granules. The use of heparin is as an Anticoagulation agent. There are different functions associated with heparin such as cell growth regulation, the proliferation of cell growth, cell adhesion and so much more.
Dermatan sulfate tends to interact with the different growth factors of heparin such as the Fibroblast growth factor and it is used in the process of wound repair as well as cellular proliferation. It also has a very important role to play in brain development. Another major mucopolysaccharides function is properly demonstrated with the use of Keratan sulfate. This group is used for the hydration of tissues. They tend to regulate the entire process of macrophage adhesion as well.
The cells of mucopolysaccharides also help in the building of different areas such as tendons, cartilage, skin, and other connective tissues.
What is Mucopolysaccharidosis?
The mucopolysaccharidosis can be defined as a group of different metabolic diseases that are caused due to the absence of particular enzymes in the body. The enzymes that are absent from the body are the ones that are responsible for the breaking down of molecules such as mucopolysaccharides. These cells are found mostly in the joints that are responsible for the lubrication of the human joints.
People who suffer from the mucopolysaccharides disorder tend to have a deficiency of at least one of the 11 different enzymes that are required to break the mucopolysaccharides down. Over time, these cells of mucopolysaccharides tend to collect themselves in the blood and the cells as well as the spinal cord and the brain. Since the result is pretty much permanent, it results in progressive damage of the cells that in turn affects the appearance, organ systems, and certain physical abilities of the individual.
Who are at risk?
Since these are seen as autosomal recessive disorders, the individuals that have the defective gene transferred from both parents will be affected. In case the parents have a defective gene each, there is a ¼ chance that the child will have the affected gene as well. So, it can be said that genetics is one of the major causes of mucopolysaccharides disorder in people. There are some other factors such as the family history of the person. It is also seen that the parents that don’t carry the symptoms of the disease but have the gene can transfer it to the children.
What are the Sign and Symptoms of Mucopolysaccharides Disorders?
There are many features associated with the disorders but the degrees of severity are differentiated. While these features might not be seen from the period of birth as the effects are on the skeletal structure and the connective tissues, there is a certain age at which the symptoms begin to present themselves.
The disease causes significant damage to the neurons. Impaired motor function and pain can be due to the compression of nerve roots. Some individuals also show signs of intellectual disability while others are normal. Some individuals also have problems associated with depression, hearing impairment, hyperactivity and so much more.
The physical symptoms tend to include coarse features in the facial structure such as thick lips, enlarged mouth, flat nasal bridge, and much more. Some symptoms also include dysplasia, thickened skin, skeletal irregularities, incontinence, hernias, excessive hair in the body, etc.
Various Types of Mucopolysaccharides Disorders
Some of the different forms of disorders due to the mucopolysaccharides are mentioned below.
MPS I H (Hurler syndrome)
MPS IX (hyaluronidase deficiency)
MPS VII (Sly syndrome)
MPS VI (Maroteaux-Lamy syndrome)
MPS I S (Scheie syndrome)
There are different mucopolysaccharides present in the body of human beings. Some common mucopolysaccharide examples are keratan and heparin. These long chains of sugar tend to help in several processes related to tissue growth and cell development. However, due to overaccumulation of the mucopolysaccharides, certain individuals have the chance of developing certain disorders that are known as mucopolysaccharides disorders.
FAQs on Mucopolysaccharidosis: Complete Overview for Students
1. What exactly is mucopolysaccharidosis (MPS)?
Mucopolysaccharidosis, or MPS, is not a single disease but a group of rare, inherited metabolic disorders. They occur when the body lacks or has a malfunctioning enzyme needed to break down long chains of sugar molecules called mucopolysaccharides (also known as glycosaminoglycans or GAGs). When these molecules are not broken down, they build up in cells, tissues, and organs, causing progressive damage.
2. What is the underlying genetic cause of mucopolysaccharidosis?
MPS is primarily a genetic disorder. In most cases, it is inherited in an autosomal recessive pattern, which means a child must inherit a non-working gene from both parents to be affected. The defective gene fails to produce a functional enzyme required for breaking down specific GAGs. Each type of MPS is linked to a deficiency in a different enzyme.
3. Why is MPS often called a 'lysosomal storage disease'?
This name describes exactly where the problem occurs inside our cells. Lysosomes act as the cell's recycling centres, containing enzymes to break down waste. In MPS, the specific enzyme meant to break down mucopolysaccharides is missing. As a result, these molecules get trapped and 'stored' within the lysosomes, causing them to swell and disrupt normal cell function, hence the term lysosomal storage disease.
4. What are some of the common symptoms and signs of MPS disorders?
Symptoms vary depending on the specific type of MPS but often become more apparent as a child grows. Common features can include:
- Distinctive or 'coarse' facial features.
- Short stature and skeletal abnormalities.
- Stiff joints and limited mobility.
- Enlargement of the liver and spleen (hepatosplenomegaly).
- Clouding of the cornea, affecting vision.
- Hearing loss and recurrent ear infections.
- In some types, developmental delays or intellectual disability.
5. How do the different types of mucopolysaccharidosis differ from each other?
The main differences between the types of MPS (like MPS I, MPS II, etc.) are based on two factors:
- The specific enzyme that is deficient: Each type is caused by a different missing enzyme.
- The type of GAG that accumulates: Because the enzymes are different, the sugar molecule that builds up is also different.
6. How do doctors typically diagnose mucopolysaccharidosis?
Diagnosing MPS usually involves a few key steps. It often starts with a doctor observing the physical symptoms. A urine test is then performed to check for excess GAGs being excreted. If the urine test is positive, a definitive diagnosis is made through an enzyme assay, which is a blood or skin cell test that measures the activity of specific enzymes to identify which one is deficient.
7. Since MPS is genetic, is there a cure? What do treatments aim to do?
Currently, there is no cure for mucopolysaccharidosis. Treatment focuses on managing the symptoms and improving the patient's quality of life. Key therapeutic approaches include:
- Enzyme Replacement Therapy (ERT): This therapy provides the missing enzyme to the body intravenously to help break down the stored GAGs.
- Hematopoietic Stem Cell Transplantation (HSCT): Also known as a bone marrow transplant, this can provide the body with new cells that produce the correct enzyme.
- Symptomatic Care: This includes surgeries to correct skeletal issues, physical therapy to improve joint mobility, and managing heart and breathing problems.
