of Antonella Sparvoli
The cells that carry oxygen become inelastic, take on a characteristic shape and tend to “stack” in the smallest vessels, slowing down the blood flow
Sickle cell anemia is crossing borders and, although in Italy it is among the rare diseases and in the past it was endemic in Sicily and Calabria, the cases are increasing in relation to the new migratory flows. In fact, many of the affected individuals come from countries where this genetic disease is still very widespread, such as sub-Saharan Africa, some areas of the Middle East and India, Albania. In these areas, sickle cell anemia has in fact found fertile ground to take root because the presence of the mutated gene has proved to be advantageous, conferring a certain degree of protection from malaria.
What is it due to?
«Sickle cell anemia or sickle cell disease is a congenital disease that involves a qualitative alteration of hemoglobin – explains Gian Luca Forni, director of the Center for microcythemia, congenital anemia and iron dysmetabolism of the Galliera Hospital in Genoa and president of the Italian Society of Thalassemia and Hemoglobinopathies (SITE) -. The replacement of a single “brick” (a single amino acid) in a part (beta chain) of this globular protein gives rise to the so-called emoglobina S(HbS). This is insoluble and tends to form aggregates, especially when the oxygen concentration falls below a certain threshold, which causes the entire red blood cell to lose its elasticity, assuming the characteristic sickle shape which gives its name to the disease “.
What does this change in shape entail?
“Under conditions of reduced oxygen concentration, the red blood cells that have assumed the shape of a sickle they tend to stack up, risking to clog small vessels. These vaso-occlusions trigger painful fits, especially in areas where the presence of oxygen is lower, for example the limbs. Vaso-occlusive crises are time-dependent and can also affect other organs with the risk of severe acute manifestations such as acute pulmonary syndromes or stroke. To try to avoid this evolution, they must be promptly recognized and treated in the first half hour of arrival at the emergency room triage. In addition, sickle cell anemia determines a chronic inflammatory state which in the long term can have repercussions on other organs such as the liver with cirrhosis or the kidney with renal insufficiency. Those who suffer from it, in addition to presenting anemia, also have a greater susceptibility to infections linked to the malfunctioning of the spleen ».
How can it be cured?
«Treatment is aimed primarily at preventing infections with vaccinations and, in the first years of life, with antibiotic prophylaxis, as well as to prevent or in any case quickly treat vaso-occlusive crises. The drug that is used for preventive purposes ishydroxyurea, which, among other actions, increases the concentration of fetal hemoglobin at the expense of the altered one, but does not give absolute coverage. A new drug has recently been approved in Europe, the crizanlizumab monoclonal antibody, which acts by inhibiting the processes of multicellular adhesion, thus counteracting chronic inflammation and reducing vaso-occlusive crises. In the most severe forms, cycles of transfusions or erythrocyte exchanges can also be used, which remove the patient’s blood and replace it with healthy blood. To date, the only potentially curative approach for sickle cell anemia is the bone marrow transplant gives good results from a compatible donor ».
Can it be diagnosed in newborns?
In Italy a newborn screening program is not currently active for sickle cell anemia and other hemoglobinopathies. However, since thalassemia is very common, the dosage of hemoglobin fractions in preconception or in the first trimester of pregnancy. “Thanks to this exam it is possible to check for the presence of thalassemia, but also of the less common sickle cell anemia, and then possibly propose a targeted examination on the child if the mother and father are carriers of altered hemoglobin (HbS) – explains Gian Luca Forni -. This also allows you to verify that the woman is not affected and never diagnosed, given that pregnancy in a sicklematic woman is strongly at risk ».
Per raise awareness among the population on sickle cell anemia, thalassemia and the importance of blood donation, a lifeline for those suffering from these diseases, the campaign has come to life «Blood Artists», promoted by Novartis together with various associations and with the patronage of Site (Soc. Italiana Thalassemias and Hemoglobinopathies) (www.instagram.com/blood.artists).
July 17, 2021 (change July 17, 2021 | 19:47)
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