Every June 19 we celebrate World Sickle Cell Day, one of the main genetic diseases of the blood with more than 50 million people affected worldwide.
What is sickle cell disease?
Sickle cell disease is the most common and best-known form of structural hemoglobinopathy. It is very frequent in the black population, mainly, but also in the Hispanic, Arab, Indian and Caucasian of southern Europe. The World Health Organization (WHO) estimates that this disease affects more than 1,600 million people, that is, almost 25% of the world population, with the highest prevalence in children, of whom almost 50% die before their birthday. 5 years.
Clinically it is characterized by anemia, bone and joint pain, leg ulcers and painful crises. It is genetically transmitted as an incomplete autosomal dominant trait.
Hemoglobin S (HbS) results from the substitution of a charged amino acid, located in the sixth position of the β chain, for another neutral one (valine). This modification of the surface charge of hemoglobin decreases the solubility of Hb, especially in its reduced state, and facilitates the formation of fibrillar aggregates or Hb molecule polymers, which profoundly alter erythrocyte morphology and increase its rigidity. In other words, it is a condition in which red blood cells are not the way they should be. Red blood cells usually have the appearance of rounded discs. But in sickle cell disease they are shaped like a crescent moon or an ancient tillage tool called a sickle (in fact, “sickle” means sickle-shaped).
Red blood cells deformed by this mechanism are called sickle cells and, due to their high rigidity, they cannot normally pass through the microcirculation of the tissues, being hemolyzed and eliminated from it by macrophages of the phagocyte mononuclear system. Which results in an increase in blood viscosity, formation of microthrombi and occlusion of small vessels (Ischemia and microinfarcts)
This hemoglobinopathy S can exist in 4 different forms:
– Heterogocite form or sickle trait (HbAS). A curious fact is that the people with this form the Hb S mutation gives them protection against malaria.
– Homozygous form or sickle cell anemia (HbSS)
– Double heterogocite form or thalassemia (HbS-Tal)
– Double heterozygous form (HbS-HbC)
Once the diagnosis of sickle cell disease has been obtained, it should be reported immediately for genetic counseling.
How is sickle cell disease treated?
So far, the only possible total cure for sickle cell disease is to perform a bone marrow transplant, which is, in principle, only contemplated for hematopoietic (healthy cells) or sibling cord parents. In addition to being very complicated procedures, they are only an option for some patients. Otherwise, patients are prescribed with a conventional base treatment that includes: folic acid, penicillin, blood transfusions, chelating therapy (in case of high ferritin, that is, large amounts of iron in the blood), immunizations, treatment specific for acute complications and hydroxyurea (a chemotherapeutic drug that increases hemoglobin).
In addition, in 2019, the United States Food and Drug Administration (FDA) approved the first therapy directed specifically for sickle cell anemia, Adakveo, a treatment to reduce the frequency of vaso-occlusive crises (a common complication and painful of this disease that occurs when the blood circulation is obstructed by sickle red blood cells, for patients over 16 years of age).
Why do we celebrate World Sickle Cell Day on June 19?
World Sickle Cell Day is a day recognized by the United Nations to give greater visibility and raise awareness of the impact it causes on the health of those who suffer from it and to improve the management of their individual health and their physical, mental and social well-being at the national and international level. On December 22, 2008, the United Nations General Assembly adopted a resolution recognizing sickle cell disease as a public health problem and “one of the most important genetic diseases in the world”.
This day, June 19, we commemorate the birth of the first patient diagnosed with sickle cell disease (it was set on june 19 but was actually born on june 21) , Walter Clement Noel (1884-1916), born in northern Grenada, a small Caribbean island that at that time was a British colony, within a family of African descent of wealthy landowners;and whose medical reviews and investigations were carried out by Dr. James B. Herrick and intern Ernest E. Iron of the Chicago Presbyterian Hospital, in 1910. The discovery of deoxygenation by Hahn and Gillespie in 1920 was also decisive, the research articles that concluded the hereditary nature of Colonel E. A Beet and JV’s disease Neel in 1949 or the discovery of the chemical composition of hemoglobin by Nobel Prize winner Dr. Linus Pauling and his colleague Dr. Harvey Itano.
And so until today when medical scientists, along with the commitment of pharmaceutical companies, continue to advance research and look for new ways to treat the disease, such as the winner of the Harrington 2020 Prize, Stuart H. Orkin, recognized for his groundbreaking discoveries in red blood cells to control and reactivate fetal hemoglobin.
So with everything, given the state of pandemic that we are experiencing caused by Covid-19 and, also, taking into account that sickle cell patients are a special group of risk, today more than ever, we must give them a voice with greater visibility, knowledge and understanding of the disease, ensure the research and development of new therapies and support both patients and their families and / caregivers who day by day experience and live through the challenges it poses.