Myeloproliferative syndromes: types and causes
Most people are familiar with the term leukemia. You know that it is a very aggressive and dangerous type of cancer in which cancer cells are found in the blood, affecting babies to the elderly and probably also originating in the bone marrow. It is one of the best known myeloproliferative syndromes. But it is not unique.
In this article we will briefly describe what myeloproliferative syndromes are and indicate some of the most frequent ones.
Myeloproliferative syndrome: what are they?
The myeloproliferative syndromes are a group of syndromes characterized by the presence of an excessive and accelerated growth and reproduction of one or more types of hematic or blood cells ; specifically of the myeloid lines. In other words, there is an excess of some type of blood cells.
This type of problem is caused by an excessive production of stem cells that will end up producing red blood cells, white blood cells or platelets. In adults these cells are produced only by the bone marrow, although during development the spleen and liver also have the capacity to produce them. These two organs tend to grow in these diseases because the excessive presence of myeloids in the blood causes them to regain that function, which in turn causes an even greater increase in the number of blood cells.
Although the symptoms may vary according to the myeloproliferative syndromes we are talking about, they generally coincide in the appearance of problems typical of the anaemias, such as the presence of physical and mental weakness and fatigue. Gastrointestinal and respiratory problems, weight and appetite loss, fainting and vascular problems are also common.
Why do they occur?
The causes of these diseases are associated with mutations in the Jak2 gene on chromosome 9, which causes the erythropoietic stimulating factor or EPO to act continuously (in subjects without these mutations EPO only acts when necessary).
In most cases these mutations are not hereditary but acquired. It is speculated that may be influenced by the presence of chemicals, exposure to radiation or poisoning .
Some of the major myeloproliferative syndromes
Although new syndromes and variants of these are being discovered over time, in general myeloproliferative syndromes are classified into four types , largely differentiated by the type of blood cells that proliferate.
1. Chronic myeloid leukemia
The disease mentioned in the introduction is one of the different existing leukemias and one of the best known myeloproliferative syndromes. This type of leukaemia is caused by the excessive proliferation of a type of white blood cell known as granulocyte.
Fatigue and asthenia, bone pain, infection and bleeding are common. In addition, it will produce different symptoms depending on the organs where the cells are infiltrated.
It usually appears in three phases: the chronic phase, in which asthenia and loss of it appear due to blood viscosity, loss of appetite, kidney failure and abdominal pain (when it is usually diagnosed); the accelerated phase, in which problems such as fever, anemia, infections and thrombosis appear (this phase being the one in which bone marrow transplantation is usually used); and the blast phase, in which the symptoms worsen and the level of cancer cells exceeds twenty percent . Chemotherapy and radiotherapy are often used, along with other drugs that can fight cancer.
2. Polycythemia vera
Polycythemia vera is one of the disorders classified within the myeloproliferative syndromes. In polycythemia vera, bone marrow cells cause erythrocytosis, or the excessive presence of red blood cells (the cells that carry oxygen and nutrients to other structures in the body) in the blood. More than the number of cells, what marks the emergence of this disease is the amount of haemoglobin that is transported. A higher number of white blood cells and platelets is also observed.
The blood becomes thicker and more viscous , which can lead to occlusions and thrombosis, as well as unexpected bleeding. Typical symptoms include flushing, congestion, weakness, itching and pain of varying intensity (especially in the abdomen, dizziness and even vision problems. One of the more specific symptoms is widespread itching throughout the body. Pain with redness of the extremities is also common, caused by occlusion and circulation difficulties in the small blood vessels. Uric acid is also often triggered.
Although is serious, chronic and requires treatment and control of possible complications , this disease does not usually shorten the life expectancy of the sufferer if treated correctly.
3. Essential Thrombocythemia
This syndrome is characterized by the excessive production and presence of platelets in the blood. These cells mainly fulfill the function of coagulating the blood and are related to the healing capacity of wounds.
The main problems that this disease can cause are the provoking of thrombosis and hemorrhages in the subject, which could have serious repercussions on the health and even end the life of the subject if these occur in the brain or heart. It can lead to myelofibrosis, which is much more complex.
It is generally considered that this problem does not necessarily shorten the life of the sufferer either, although regular checks should be made to control the level of platelets and, if necessary, reduce it by treatment.
Myelofibrosis is a disorder. It can be primary if it occurs by itself or secondary if it is derived from another disease.
Myelofibrosis is one of the most complex myeloproliferative syndromes . In this case, the stem cells in the bone marrow that should be produced by the blood cells generate them in excess in such a way that, in the long run, increases are generated in the fibers of the marrow that end up causing the growth of a kind of scar tissue that takes the place of the marrow. The blood cells also end up being immature and unable to perform their functions in a normative way.
The main symptoms are due to the anemia caused by the immaturity of the blood cells , the excessive growth of the spleen caused by this and alterations in the metabolism. Thus, fatigue, asthenia, sweating, abdominal pain, diarrhea, weight loss and edema are common.
Myelofibrosis is a serious disease in which anaemia and even a drastic reduction in the number of functional platelets appear, which can lead to serious bleeding. In some cases it can lead to leukaemia.
- Hernández, L.; Besses, C. and Cervantes, F. (2015). Myeloproliferative syndromes. General information for the patient. AEAL Explains. Madrid.