Signs and Symptoms
- Sickle cell disease usually begins in early childhood
- Severity of symptoms can vary from person to person
- Acute and chronic complications can occur, with high mortality rates
- Sickle cell crisis can manifest in various types, including vaso-occlusive crisis, aplastic crisis, splenic sequestration crisis, and haemolytic crisis
- Most episodes of sickle cell crises last between five and seven days
- Vaso-occlusive crisis is caused by sickle-shaped red blood cells obstructing capillaries and restricting blood flow, resulting in ischemia, pain, necrosis, and organ damage
- Splenic sequestration crisis is characterized by acute and painful enlargements of the spleen, caused by sickle-shaped red blood cells narrowing blood vessels and reducing spleen function
- Acute chest syndrome is defined by chest pain, fever, pulmonary infiltrate or abnormality, respiratory symptoms, or hypoxemia
- Aplastic crisis is an acute worsening of baseline anemia triggered by parvovirus B19
Complications
- Increased risk of severe bacterial infections due to loss of functioning spleen tissue
- Stroke can result from progressive narrowing of blood vessels
- Silent stroke causes damage to the brain
- Cholelithiasis and cholecystitis may result from excessive bilirubin production
- Avascular necrosis of the hip and other major joints may occur
Genetics
- Sickle cell disease is inherited in an autosomal recessive pattern
- Different geographic areas have different variants of the sickle cell gene mutation
- The gene defect is a single nucleotide mutation of the β-globin gene
Other Complications
- Decreased immune reactions due to hyposplenism
- Priapism and infarction of the penis
- Osteomyelitis is a common cause of bone infection
- Acute papillary necrosis in the kidneys
- Eye complications such as retinopathy and blindness can occur
Diagnosis and Management
- Diagnosis involves complete blood count, blood film, hemoglobin electrophoresis, and other tests
- Management includes regular exercise, hydration, calcium-rich diet, and L-glutamine use
- Penicillin is recommended for children with sickle cell disease
- Malaria prevention is important for individuals with sickle cell trait
- Treatment for vaso-occlusive crises involves pain management and fluid replacement
- Transcranial Doppler ultrasound and blood transfusions are used for stroke prevention
- Acute chest syndrome is managed similarly to vaso-occlusive crisis, with antibiotics and supportive care
- Hydroxyurea and bone marrow transplant are treatment options for sickle cell disease
Sickle cell disease (SCD), one of the hemoglobinopathies, is a group of blood disorders typically inherited. The most common type is known as sickle cell anaemia. It results in an abnormality in the oxygen-carrying protein haemoglobin found in red blood cells. This leads to a rigid, sickle-like shape under certain circumstances. Problems in sickle cell disease typically begin around 5 to 6 months of age. A number of health problems may develop, such as attacks of pain (known as a sickle cell crisis), anemia, swelling in the hands and feet, bacterial infections, and stroke. Long-term pain may develop as people get older. The average life expectancy in the developed world is 40 to 60 years.
| Sickle cell disease | |
|---|---|
| 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 |
| Complications | Chronic pain, stroke, aseptic bone necrosis, gallstones, leg ulcers, priapism, pulmonary hypertension, vision problems, kidney problems |
| Usual onset | 5–6 months of age |
| Causes | Genetic, Homozygous mutation in the hemoglobin S gene. |
| Diagnostic method | Blood test |
| Treatment | Vaccination, antibiotics, high fluid intake, folic acid supplementation, pain medication, blood transfusions |
| Prognosis | Life expectancy 40–60 years (developed world) |
| Frequency | 4.4 million (2015) |
| Deaths | 114,800 (2015) |
Sickle cell disease occurs when a person inherits two abnormal copies of the β-globin gene (HBB) that makes haemoglobin, one from each parent. This gene occurs in chromosome 11. Several subtypes exist, depending on the exact mutation in each haemoglobin gene. An attack can be set off by temperature changes, stress, dehydration, and high altitude. A person with a single abnormal copy does not usually have symptoms and is said to have sickle cell trait. Such people are also referred to as carriers. Diagnosis is by a blood test, and some countries test all babies at birth for the disease. Diagnosis is also possible during pregnancy.
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. Other measures may include blood transfusion and the medication hydroxycarbamide (hydroxyurea). In 2023, new gene therapies were approved. 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. About 80% of sickle cell disease cases are believed to occur in Sub-Saharan Africa. 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. In 2015, it resulted in about 114,800 deaths. The condition was first described in the medical literature by American physician James B. Herrick in 1910. In 1949, its genetic transmission was determined by E. A. Beet and J. V. Neel. In 1954, the protective effect against malaria of sickle cell trait was described.
