Hereditary spherocytosis is a blood disorder that, as the name implies, is inherited. It consists of the morphology of erythrocytes (red blood cells) is altered.
Red blood cells are usually disc-shaped. However, people with hereditary spherocytosis have them shaped like a sphere. Therefore, they are more fragile and tend to degrade faster than normal ones. Hence, the pathology can have serious complications, in addition to anemia.
What is hereditary spherocytosis?
As explained in a study published in the Cuban Journal of Hematology, Immunology and Hemotherapy, hereditary spherocytosis was described for the first time in 1871. However, it was not until the 1970s when it was conceived as it is known today.
Thanks to advances in science it was found that red blood cells had a different morphology due to alterations in the proteins that make up their membrane. Furthermore, the genetic mutations that can lead to the disease have already been established.
As stated Orphanet, hereditary spherocytosis has a prevalence of 1 in 2000 people in Northern Europe. It is also considered the most common cause of chronic hereditary hemolysis in the United States.
Hemolysis is the process by which red blood cells break down. These cells, on average, live 120 days. They are then self-destructing in organs such as the spleen, liver, or bone marrow. Thus, they are constantly being renewed so that they are able to adequately fulfill their functions.
Hereditary spherocytosis is a type of hemolytic anemia. What happens is that these erythrocytes die before their time. The marrow is unable to create new red blood cells at the rate at which they are destroyed. The reason for the destruction is the anomalous shape.
What are the causes?
Hereditary spherocytosis is a pathology in which the shape of red blood cells is altered. These, physiologically, are disc-shaped. However, in this disease they are shaped like spheres.
This is because a defect occurs in certain proteins in the cell's membrane. These defects lead to loss of cohesion, which is why a different shape is adopted. Also, red blood cells lose some of their deformability.
The latter is essential. It is important to know that erythrocytes travel through the blood vessels of the body and there are areas where they must pass through very tight spaces. Their intrinsic deformability characteristic allows them to do so without breaking. However, this quality is absent in hereditary spherocytosis.
That is why they are destroyed prematurely, especially in the spleen. In the same study that we have pointed out before, they explain that the proteins that are usually altered are the following:
The alpha and beta chains of erythrocyte spectrin 1.
The erythrocyte membrane protein (band 4.2).
The anion exchanger (band 3).
Who can develop the disease?
Hereditary spherocytosis is a disease that is inherited in an autosomal dominant manner. This means that, by inheriting the mutated gene from one of the parents, it usually already occurs. It has been seen that there are also cases of recessive inheritance and mutations de novo, although they are less frequent.
Therefore, a person who has the disease is very likely to pass it on to their offspring. However, a study carried out by the Spanish Federation of Rare Diseases explains that in 25-30% of patients no abnormalities are found in the parents.
Furthermore, hereditary spherocytosis has a very large clinical variability. Some people are asymptomatic carriers, while others may have a severe, life-threatening strain.
You may be interested: Anemia and iron deficiency, are they the same?
Symptoms of hereditary spherocytosis
Symptoms of hereditary spherocytosis vary. However, most patients have moderate anemia. Symptoms are usually most severe during the first year of life. At this time almost all diagnoses are made.
The first sign to appear is jaundice. It is the yellowing of the skin and mucous membranes, as a result of the high concentration of bilirubin. In turn, this substance is elevated due to hemolysis. Free bilirubin is associated with an increased risk of gallstones.
On the other hand, as explained by specialists in KidsHealth, anemia usually leads to tiredness, pale skin, growth problems and heart rhythm disturbances. There is also usually splenomegaly and hepatomegaly (enlarged spleen and liver, respectively).
In the MSD Manual they state that certain situations, such as infections, can cause the production of red blood cells to decrease. That is why episodes appear in which anemia worsens.
You might be interested: 7 warning signs of anemia in children
Diagnosis of hereditary spherocytosis
In order to diagnose hereditary spherocytosis, it is essential that the doctor knows all the symptoms and if there is a family history. In addition, a thorough physical examination is necessary.
This will check if there are changes in the color of the skin or if the spleen and liver are enlarged. Once there is suspicion that it may be hereditary spherocytosis, certain laboratory tests are usually ordered.
The first thing is to do a blood test. Through this test it is possible to observe if there is anemia and if there are other altered parameters. Those that orient the most towards hereditary spherocytosis are the mean corpuscular volume and corpuscular diameter, which are lower than normal.
Also, there are usually many reticulocytes in the blood. Reticulocytes are immature red blood cells, derived from the bone marrow. A peripheral blood smear may be performed to observe the morphology under a microscopeof cells. Erythrocyte fragility and autohemolysis tests are also used.
How is it treated?
Treatment of hereditary spherocytosis is complex. In newborns it is usually necessary to start the approach quickly. The main reason is the increase in bilirubin. Therefore techniques such as phototherapy and blood transfusion are used, to reduce jaundice.
Transfusions are also necessary for those who have severe anemia. In some cases, erythropoietin can be given. It is a substance that stimulates the synthesis of red blood cells.
The removal of the spleen is also evaluated. It is a surgery that receives the name of splenectomy. As the spleen is the organ in which red blood cells are most destroyed, anemia is less severe. Anyone undergoing the procedure needs to be vaccinated against certain germs, such as pneumococcus.
Hereditary spherocytosis is a serious disease
Hereditary spherocytosis, as we have seen, is a type of hemolytic anemia. What happens is that the red blood cells have an abnormal morphology. This makes them tend to break down quickly, which can lead to anemia and jaundice.
Although there are many varieties in the form of presentation, most of the patients have a moderate anemia. This often causes symptoms such as tiredness, rapid heartbeat, and paleness. Therefore it is important that these people visit the doctor frequently and are treated appropriately.