Sickle cell disease | |
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Other names | Sickle cell disorder; drepanocytosis (dated) |
Figure (A) shows normal red blood cells flowing freely through a blood vessel. The inset shows a cross-section of a normal red blood cell with normal haemoglobin. Figure (B) shows abnormal, sickled red blood cells sticking at the branching point in a blood vessel. The inset image shows a cross-section of a sickle cell with long polymerized sickle haemoglobin (HbS) strands stretching and distorting the cell shape to look like a crescent moon. | |
Specialty | Hematology, medical genetics |
Symptoms | Attacks of pain, anemia, swelling in the hands and feet, bacterial infections, stroke[1] |
Complications | Chronic pain, stroke, aseptic bone necrosis, gallstones, leg ulcers, priapism, pulmonary hypertension, vision problems, kidney problems[2] |
Usual onset | 5–6 months of age[1] |
Causes | Genetic, Homozygous mutation in the hemoglobin S gene.[3] |
Diagnostic method | Blood test[4] |
Treatment | Vaccination, antibiotics, high fluid intake, folic acid supplementation, pain medication, blood transfusions[5][6] |
Prognosis | Life expectancy 40–60 years (developed world)[2] |
Frequency | 4.4 million (2015)[7] |
Deaths | 114,800 (2015)[8] |
Sickle cell disease (SCD), also simply called sickle cell, is a group of hemoglobin-related blood disorders typically inherited.[2] The most common type is known as sickle cell anemia.[2] It results in an abnormality in the oxygen-carrying protein haemoglobin found in red blood cells.[2] This leads to a rigid, sickle-like shape under certain circumstances.[2] Problems in sickle cell disease typically begin around 5 to 6 months of age.[1] A number of health problems may develop, such as attacks of pain (known as a sickle cell crisis) in joints, anemia, swelling in the hands and feet, bacterial infections, dizziness[9] and stroke.[1] Long-term pain may develop as people get older.[2] The average life expectancy in the developed world is 40 to 60 years. It often gets worse with age.[10] All the major organs are affected by sickle cell disease. The liver, heart, kidneys, gallbladder, eyes, bones, and joints also can suffer damage from the abnormal functions of the sickle cells, and their inability to flow through the small blood vessels correctly.[11]
Sickle cell disease occurs when a person inherits two abnormal copies of the β-globin gene (HBB) that makes haemoglobin, one from each parent.[3] This gene occurs in chromosome 11.[12] Several subtypes exist, depending on the exact mutation in each haemoglobin gene.[2] An attack can be set off by temperature changes, stress, dehydration, and high altitude.[1] A person with a single abnormal copy does not usually have symptoms and is said to have sickle cell trait.[3] Such people are also referred to as carriers.[5] Diagnosis is by a blood test, and some countries test all babies at birth for the disease.[4] Diagnosis is also possible during pregnancy.[4]
The care of people with sickle cell disease may include infection prevention with vaccination and antibiotics, high fluid intake, folic acid supplementation, and pain medication.[5][6] Other measures may include blood transfusion and the medication hydroxycarbamide (hydroxyurea).[6] In 2023, new gene therapies were approved.[13][14] A small percentage of people can be cured by a transplant of bone marrow cells.
As of 2015[update], about 4.4 million people have sickle cell disease, while an additional 43 million have sickle cell trait.[7][15] About 80% of sickle cell disease cases are believed to occur in Sub-Saharan Africa.[16] It also occurs to a lesser degree in parts of India, Southern Europe, West Asia, North Africa and among people of African origin (sub-Saharan) living in other parts of the world.[17] In 2015, it resulted in about 114,800 deaths.[8] The condition was first described in the medical literature by American physician James B. Herrick in 1910.[18][19] In 1949, its genetic transmission was determined by E. A. Beet and J. V. Neel.[19] In 1954, the protective effect against malaria of sickle cell trait was described.[19]
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