Mucopolysaccharidosis is a collective term for lysosomal storage diseases that are based on the storage of glycosaminoglycans. All diseases develop similar symptoms and forms. The severity of the syndromes vary greatly.
What is mucopolysaccharidosis?
There is no such thing as mucopolysaccharidosis as a single disease. The term mucopolysaccharidosis is a collective term for a large number of storage diseases. These are based on storage disorders of glycosaminoglycans (GAG) in the lysosomes of the cells. The storage is progressive because the termination of the connections does not work. See foodezine for Everything about Dilated Cardiomyopathy.
All mucopolysaccharidoses are genetic. Each disease lacks a specific enzyme that catalyzes the breakdown of the corresponding GAG. All mucopolysaccharidoses are very rare diseases and often show similar courses. If left untreated, the constantly increasing deposits destroy the cells. The organs are destroyed. The disease can begin in infancy as well as in adulthood.
Mucopolysaccharidosis can be caused by four different groups of glycosaminoglycans:
- heparan sulfate
- keratan sulfate
- chondroitin sulfate
- dermatan sulfate.
All glycosaminoglycans consist of a polysaccharide chain attached to a protein. The carbohydrate content makes up 95 percent and the protein content five percent of the molecular mass. Depending on which glycosaminoglycan and which enzyme is affected, a distinction can be made between six different main forms of mucopolysaccharidosis: These include Hurler / Scheie disease (MPS I), Hunter disease (MPS II), Sanfilippo disease (MPS III), Morquio disease (MPS IV), Maroteaux-Lamy disease (MPS VI) and Sly disease (MPS VII). All types have severe and mild forms.
The cause of all mucopolysaccharidoses is an increasing storage of glycosaminoglycans (GAGs) in the lysosomes of the cells. The degradation of the corresponding biopolymers is disturbed. For each individual disorder, either a specific enzyme is missing or this enzyme is malfunctioning. There can also be several mutations for each enzyme . The inheritance of the corresponding mutation can be autosomal recessive, autosomal dominant or X-linked recessive.
Since an enzymatic process usually takes place over several reaction steps, several enzymes can theoretically be mutated for the same glycosaminoglycan. However, the symptoms of the disorder would be the same or similar.
- In MPS I, Hurler’s disease or Scheie’s disease, the enzyme alpha-l-iduronidase is defective.
- MPS II represents Hunter syndrome with a defective iduronate-2-sulfatase.
- Sanfilippo syndrome (MPS III) can be divided into several subtypes. Several enzymes can be affected in this disease.
- Morquio disease (MPS IV) is caused by a defective β-galactosidase.
- In Maroteaux-Lamy syndrome (MPS VI), it is N-acetyl-galactosamine-4-sulfatase.
- Sly’s disease (MPS VII) is caused by defective β-glucuronidase. When the corresponding glycosaminoglycans are stored in the lysosomes, they become larger and larger.
The cells also increase in size because they require more and more space for GAGs that have not been degraded. This is also noticeable in the enlargement of many organs. A typical symptom is the constant enlargement of the liver and spleen. If left untreated, the storage diseases lead to death through the gradual destruction of the organs.
Symptoms, Ailments and Signs
The symptoms are similar for all diseases. There are severe and mild forms. However, a mild course only means that the disease progresses more slowly. The end result is always the same. There is progressive deformation of the skeletal system, joint contractures, coarsening of facial features, and enlargement of the liver and spleen.
Mental and motor skills decrease in the short or long term. In the severe forms of the disorders, the symptoms are very similar. Umbilical and inguinal hernias, heart problems and respiratory infections occur early on. Over time, massive sleep apnea problems develop due to the narrowing of the airways and the enlargement of the tonsils and pharyngeal tonsils.
Diagnosis and course of the disease
Mucopolysaccharidoses can be diagnosed by examining the urine for excreted glycosaminoglycans. In the case of mucopolysaccharidosis, the values are always elevated. Furthermore, the activity of the suspected defective enzyme in the leukocytes or fibroblasts can be determined. A specific excretion pattern of the glycosaminoglycans leads to the suspicion of a corresponding enzyme, which is then examined.
Those affected suffer from various malformations and skeletal disorders as a result of mucopolysaccharidosis. This causes deformations that can significantly restrict the patient’s everyday life. As a rule, the joints are also affected by mucopolysaccharidosis, resulting in restrictions in the patient’s movement.
Children in particular are affected and suffer from severely delayed development, so that various consequential damage can also occur in adulthood. It is not uncommon for mucopolysaccharidosis to lead to heart or breathing problems. In the worst case, sudden cardiac death can result in the death of the affected person. Due to the breathing difficulties, the patients suffer from fatigue and exhaustion.
The resilience of those affected also decreases enormously. Not infrequently, breathing difficulties at night can lead to sleep problems and thus to depression. The patient’s quality of life is significantly reduced by mucopolysaccharidosis. Unfortunately, a causal treatment of this disease is not possible. Those affected are therefore dependent on bone marrow donors in order to be able to treat the symptoms. There are no particular complications. However, in most cases, patients are dependent on lifelong therapy.
When should you go to the doctor?
Changes and abnormalities in the physique indicate a health impairment. A doctor’s visit is necessary as soon as permanent optical peculiarities occur or the person concerned has trouble optimizing his posture at will. Swelling of the joints, changes in facial features or enlargement of the chest should be examined intensively by a doctor so that a diagnosis can be made. If there are limitations in mobility, irregularities in everyday voluntary control and a decrease in physical and mental performance, a doctor is needed. A doctor should be consulted in the event of cardiac arrhythmias, respiratory problems and interruptions during the night’s sleep.
Swelling in the throat, a feeling of tightness in the throat, disturbances in the act of swallowing and changes in vocalization are considered alarming. They must be evaluated by a doctor so that relief of the symptoms can be initiated. If the person concerned suffers more infections, the concentration and attention capacity decreases or if there are repeated umbilical or inguinal hernias, a doctor must be informed of the observations.
Sudden skin blemishes, yellowing of the skin and inner restlessness should be examined and treated. A doctor is needed as soon as there is pain in the body, a reduced quality of life and behavioral problems. If there is a risk of shortness of breath, an ambulance is required. In order to prevent this acute condition, a doctor should be consulted as early as possible.
Treatment & Therapy
A causal therapy is not yet possible. However, there are some approaches to a future gene therapy of these diseases in research projects. Unfortunately, there are still no tangible results in this area. However, a clinical study on gene therapy is to start in Barcelona for Hurler’s disease. In some forms of mucopolysaccharidosis, bone marrow transfers have proven effective in individual cases. This applies, for example, to Hunter’s disease, Hurler’s disease or Sanfilippo’s disease.
Through this bone marrow transplant, the diseased stem cells are exchanged for healthy stem cells from a donor. As a result, the organism can produce the missing enzyme again in sufficient quantities. Enzyme replacement therapy also pays off in many cases. However, this replacement therapy must be carried out for life. However, there are also cases in which promising therapies are no longer possible. The point here, however, is to carry out symptomatic treatments.
Outlook & Forecast
The further development in patients with mucopolysaccharidosis must be assessed individually. This term is a collective term for various storage diseases. These are present to different degrees in each patient and are individually pronounced in their intensity. If medical care is not initiated, the internal organs will gradually be destroyed over the lifetime of all those affected. This results in a reduction in the average life expectancy.
With an early diagnosis, a personally optimized therapy can be worked out. This is linked to the health conditions and existing complaints of the patient. Long-term treatment is fundamentally necessary in order to achieve a stable improvement in health. Surgical interventions can occur, each of which is associated with different risks and side effects. If the operation proceeds without any further complications, an alleviation of the symptoms can normally be observed afterwards.
Nevertheless, unwanted developments and setbacks can occur in the course of life. In individual cases, only a bone marrow transplant can bring about an improvement in the general quality of life. Due to the overall circumstances, the patient experiences a strong emotional and psychological burden. A normal everyday life is often not possible due to the symptoms. Psychological sequelae can occur and lead to a further deterioration of the situation.
Since mucopolysaccharidoses are hereditary diseases, prevention is not possible. In the case of an existing disease, timely therapy can ensure the success of the treatment. In addition, constant monitoring of lung and heart function is required. If cases of mucopolysaccharidosis have already occurred in the family, the risk of the disease can be assessed by means of human genetic counseling if you wish to have children.
In most cases, the patient with mucopolysaccharidosis only has a few options for aftercare, so that those affected with this disease should first and foremost consult a doctor at an early stage. Only with early detection and treatment of this disease can further complications be prevented, so that a doctor should be contacted as soon as the first signs and symptoms appear.
In most cases, those affected are dependent on surgical interventions, which can alleviate and limit the symptoms. However, since mucopolysaccharidosis is a genetic disease, it cannot usually be completely cured.
Therefore, if the person concerned wants to have children, they should first consult a doctor in order to prevent the recurrence of this disease in the children. The support of one’s own family during treatment is often very important. It can also prevent depression and other mental upsets. The mucopolysaccharidosis may result in a reduced life expectancy for those affected, with the further course depending very much on the time of diagnosis.
You can do that yourself
The possibilities of self-help in mucopolysaccharidosis are limited to alleviating the symptoms and thus improving the quality of life. Self-help groups have proven to be very helpful, as the exchange with other parents reveals valuable tips and can often alleviate fears and concerns and give a more positive view of the future.
Accompaniment to physiotherapy, ergotherapy, speech therapy and other forms of therapy, which can often be deepened at home, are now an integral part of life.
In order to make life as easy as possible for you and the child concerned, it is advisable to make the living environment handicap accessible as early as possible. With increasing age and weight of the child, height-adjustable care beds prove to be a great physical relief for the people caring for them. Epilepsy warning devices and other technical aids also enable the best possible safety at night and relieve parents at night so that they can sleep more relaxed.
Keeping a symptom diary can help the doctor to identify new symptoms and possibly correct the treatment of existing symptoms, since drug therapy often has the opposite effect and not the desired effect.
Since the disease is very demanding for the relatives, they have to create a little space for themselves to recharge their batteries. This can include cures, preventive care or later a holiday in a hospice.