Causes of sickle cell anemia
Sickle cell disease is the most common inherited blood disorder in the United States. Approximately , Americans have the disease. In the United States, sickle cell disease is most prevalent among African Americans. About one in 12 African Americans and about one in Hispanic Americans carry the sickle cell trait, which means they are carriers of the disease.
Sickle cell disease is caused by a mutation in the hemoglobin-Beta gene found on chromosome Hemoglobin transports oxygen from the lungs to other parts of the body. Red blood cells with normal hemoglobin hemoglobin-A are smooth and round and glide through blood vessels. In people with sickle cell disease, abnormal hemoglobin molecules - hemoglobin S - stick to one another and form long, rod-like structures.
These structures cause red blood cells to become stiff, assuming a sickle shape. Their shape causes these red blood cells to pile up, causing blockages and damaging vital organs and tissue. Sickle cells are destroyed rapidly in the bodies of people with the disease, causing anemia. This anemia is what gives the disease its commonly known name - sickle cell anemia.
The sickle cells also block the flow of blood through vessels, resulting in lung tissue damage that causes acute chest syndrome, pain episodes, stroke and priapism painful, prolonged erection. It also causes damage to the spleen, kidneys and liver. However, the rate of fall from individual steady state haemoglobin level may trigger symptoms of hypoxia aplastic crises or a shock-like state e.
The most common cause of acquired bone marrow failure in SCD and other haemolytic disorders is caused by Parvovirus B19 [ 44 ]. This virus causes the fifth disease and normally in healthy children is quite mild, associated with malaise, fever and sometimes a mild rash; the virus affects erythropoiesis by invading progenitors of RBCs in the bone marrow and destroying them, thus preventing new RBCs from being made.
Parvovirus B19 infection usually takes about four days to one week to resolve and patients with SCD usually require a blood transfusion [ 39 , 44 ]. SCD increases susceptibility to infections, notably bacterial sepsis and malaria in children under five years [ 45 ].
Sickle cell anemia biography
Respiratory infections can trigger the sickle-cell acute chest syndrome, with a high risk of death. The main pathogen of concern is Streptococcus pneumoniae, though severe and systemic infections arise with Haemophilus influenzae , Neisseria meningitides , and Salmonellae leads to osteomyelitis especially Salmonella due to bowel ischaemia and gut flora dissemination [ 46 , 47 ].
The main function of the spleen is the removal of defective red blood cells including sickled RBCs sRBC resulting in further haemolysis [ 48 ]. Blood flow through the spleen is slow reducing oxygen tension and increased polymerisation in HbS. As a result of the narrow capillaries in the splenic vascular bed, further hypoxia occurs with RBC polymerisation and entrapment of affected blood cells.
This leads to a cycle of hypoxia, RBC polymerisation, and reduced blood flow causing the spleen to enlarge, for unexplained reasons, this may occur suddenly with pooling of blood within the vascular bed resulting in shock and circulatory failure. The rapidly increasing spleen size may lead to abdominal distension, sudden weakness, increased thirst, tachycardia and tachypnoea.
Splenic sequestration crisis is an emergency because if left untreated, it can lead to death in 1—2 h due to circulatory failure [ 49 ]. The complications listed above are highlighted as those affecting babies and young children, because these are immediately relevant after newborn screening. Older children, adolescents, and young adults develop many chronic complications: stroke, cognitive dysfunction, priapism, leg ulcers, avascular necrosis of the femoral head or humeral head , chronic pain, retinopathy, pulmonary hypertension, acute kidney injury, chronic kidney disease, thromboembolic events, and hepatic sequestration [ 50 , 51 ], cholelithiasis gallstones and cholecystitis as a result of excessive production and precipitation of bilirubin due to haemolysis.
SCD also increases susceptibility to complications in pregnancy [ 52 ]. SCD has a significant psychosocial impact on patients and families [ 53 ]. Cultural factors are particularly important to these problems because of beliefs and practices [ 54 ]. Furthermore, the ability of people with SCD to cope with their condition varies greatly because severity, general health, and quality of life varies greatly among individuals [ 55 , 56 ].
SCD causes a range of acute and long-term complications, requiring a multi-disciplinary approach, involving various medical specialists. In the United Kingdom, comprehensive SCD care is coordinated by specialist haemoglobinopathy teams [ 57 ]. Such teams play a key role in education about SCD for patients and their families, as well as guiding treatment with disease-modifying therapies, access to psychology, social and welfare support.
Additionally, they coordinate screening services such as Transcranial Doppler TCD ultrasound monitoring in children, detection of iron overload or allo-antibody formation in individuals on transfusion programmes, and referral to specialists for major organ complications with an interest in SCD. Pain is the commonest acute complication of SCD, and significantly impact health-related quality of life [ 58 ].
Pain management may vary from patient to patient depending on family dynamics and individual patient thresholds or access to health care, however mild to moderate painful episodes may be treated in the home without the need of attending a health facility. Self-help psychological strategies including distraction techniques such as guided imagery can be a useful evidence-based adjunct to managing pain, and patients who utilise complementary coping strategies tend to require fewer hospitalisations [ 53 , 59 ].
The management strategy for pain includes 4 stages: which are assessment, treatment, reassessment, and adjustment [ 60 ]. Given the fact that pain is often triggered by infection, exposure to cold or dehydration, supportive care during these episodes involves providing hydration, warmth and treating any treating the underlying infection.
Simple devices such as incentive spirometry can be critical in preventing complications such as acute chest syndrome. Longer-term infection prevention varies regionally but can involve vaccination programs and penicillin prophylaxis [ 61 ]. Currently the only available disease-modifying medications for SCD are hydroxycarbamide and l -glutamine.
Both are given daily to reduce the rate of acute complications, but results vary from person to person. The main curative therapy is stem cell transplantation while gene therapy is in the horizon in clinical Trials. Hydroxycarbamide has gained widely accepted use globally [ 62 ]. Although it was originally used as a cytoreductive agent by inhibiting ribonucleotide reductase, the main mechanism through which hydroxycarbamide works in SCD is through increasing total haemoglobin concentration and HbF production [ 63 ].
Hydroxycarbamide also reduces the number of leucocytes in blood, and reduces expression of surface adhesion molecules on neutrophils, red cells and vascular endothelium resulting in improved blood flow and reducing vaso-occlusion [ 62 ]. A number of trials in adults and children have shown beneficial effects of long-term hydroxycarbamide use, including reducing the severity and frequency of crisis in children with SCD [ 64 ].
The Multi-Centre Study of Hydroxycarbamide MSH showed that over a two-year follow-up period, adults on hydroxycarbamide had a significantly lower frequency of painful crises compared with placebo median 2. Indications for Hydroxycarbamide vary according to the phenotype, age and individual practice [ 65 ]. In adults, indications for hydroxycarbamide may include [ 66 , 67 , 68 ]:.
Hydroxycarbamide can cause birth defects in animal models, hence the caution about its use during pregnancy, but hydroxycarbamide has not yet been linked to birth defects in humans. Short term research has shown only minor side effects and the benefits of using hydroxycarbamide outweigh any short-term adverse effects [ 62 , 65 ].
The U. Food and Drug Administration FDA approved use of pharmaceutical-grade l -glutamine for sickle patients aged five years or older in July [ 69 ]. Formal clinical trials showed that this purified version of glutamine significantly reduced the frequency of acute complications of SCD. He died of pneumonia in and is buried in the Catholic cemetery at Sauteurs in the north of Grenada.
Memphis physician Lemuel Diggs , a prolific researcher into sickle cell disease, first introduced the distinction between sickle cell disease and trait in , although until , the genetic characteristics had not been elucidated by James V. Neel and E. In , the introduction of haemoglobin electrophoresis allowed the discovery of particular subtypes, such as HbSC disease.
Large-scale natural history studies and further intervention studies were introduced in the s and s, leading to widespread use of prophylaxis against pneumococcal infections amongst other interventions. Some old texts refer to it as drepanocytosis. Sickle cell disease is frequently contested as a disability. Social Security Administration issued a Policy Interpretation Ruling providing background information on sickle cell disease and a description of how Social Security evaluates the disease during its adjudication process for disability claims.
Studies have shown that those with SCD frequently feel as though they must keep their diagnosis a secret to avoid discrimination in the workplace and also among peers in relationships. By having this screening, it was intended that employees would not be placed in environments that could potentially be harmful and trigger SCD. Uganda has the 5th highest sickle cell disease SCD burden in the world.
The general gap in knowledge surrounding sickle cell disease is noted among adolescents and young adults due to the culturally sanctioned secrecy about the disease. Those who are informed about the disease learned about it from family or friends and not from health professionals. Failure to provide the public with information about sickle cell disease results in a population with a poor understanding of the causes of the disease, symptoms, and prevention techniques.
The data compiled on sickle cell disease in Uganda has not been updated since the early s. The deficiency of data is due to a lack of government research funds, even though Ugandans die daily from SCD. The stigma around the disease is particularly bad in regions of the country that are not as affected. For example, Eastern Ugandans tend to be more knowledgeable of the disease than Western Ugandans, who are more likely to believe that sickle cell disease resulted as a punishment from God or witchcraft.
In , the Uganda Sickle Cell Rescue Foundation was established to spread awareness of sickle cell disease and combat the social stigma attached to the disease.
The deeply rooted stigma of SCD from society causes families to often hide their family members' sick status for fear of being labeled, cursed, or left out of social events. This mentality robs people with SCD of the right to freely participate in community activities like everyone else [ ] SCD-related stigma and social isolation in schools, especially, can make a life for young people living with sickle cell disease extremely difficult.
It often leads the excluded individual to experience emotional distress and may result in their academic underperformance, avoidance of school, and occupational failure later in life. Mothers of children with sickle cell disease tend to receive disproportionate amounts of stigma from their peers and family members.
These women will often be blamed for their child's diagnosis of SCD, especially if SCD is not present in earlier generations, due to the suspicion that the child's poor health may have been caused by the mother's failure to implement preventative health measures or promote a healthy environment for her child to thrive.
Women living with SCD who become pregnant often face extreme discrimination and discouragement in Uganda. These women are frequently branded by their peers as irresponsible for having a baby while living with sickle cell disease or even engaging in sex while living with SCD. Burden of sickle cell trait and disease in the Uganda Sickle Surveillance Study US3 : a cross-sectional study The criticism and judgement these women receive, not only from healthcare professionals but also from their families, often leaves them feeling alone, depressed, anxious, ashamed, and with very little social support.
Burden of sickle cell trait and disease in the Uganda Sickle Surveillance Study US3 : a cross-sectional study - The Lancet Global Health Most pregnant women with SCD also go on to be single mothers as it is common for them to be left by their male partners who claim they were unaware of their partner's SCD status. Unprepared and Misinformed Parents of Children with Sickle Cell Disease: Time to Rethink Awareness Campaigns Not only does the abandonment experienced by these women cause emotional distress for them, but this low level of parental support can be linked to depressive symptoms and overall lower quality of life for the child once they are born.
In many patients were found to be afraid to visit hospitals, such was the level of ignorance among staff, so purchased pain relief to treat themselves outside the NHS. They were often waiting a long time for pain relief, and sometimes suspected of "drugs-seeking" behaviour. Delays to treatment, failure to inform the hospital haematology team and poor pain management had caused deaths.
Specialist haematology staff preferred to work in bigger, teaching hospitals, leading to shortages of expertise elsewhere. The treatment can be accessed, via consultants, at any of ten new hubs set up around the country. The campaign had twin aims. One was to increase awareness of the key signs and symptoms of the blood disorder so that people would be as alert to signs of a sickle cell crisis as they are to an imminent heart attack or stroke.
The second aim was to set up a new training programme to help paramedics, Accident and Emergency staff, carers and the general public to care effectively for sufferers in crisis.
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In other projects. Wikimedia Commons Wikidata item. Medical condition. Signs and symptoms [ edit ]. First events [ edit ]. Critical events [ edit ]. Vaso-occlusive crisis [ edit ]. Splenic sequestration crisis [ edit ]. Acute chest syndrome [ edit ]. Aplastic crisis [ edit ]. Complications [ edit ]. Genetics [ edit ]. See also: Introduction to genetics.
Malaria [ edit ]. Pathophysiology [ edit ]. Diagnosis [ edit ]. Prenatal and newborn screening [ edit ]. Tests [ edit ]. Genetic counseling [ edit ]. Treatment [ edit ]. Further information: Pain management in children. Management [ edit ]. Blood transfusion [ edit ]. Main article: Transfusion therapy Sickle-cell disease.
Stroke prevention [ edit ]. Treating avascular necrosis [ edit ].
Psychological therapy [ edit ]. Stem cell treatments [ edit ]. Gene therapy [ edit ]. Hematopoietic stem cell transplantation [ edit ]. Prognosis [ edit ]. Epidemiology [ edit ]. Africa [ edit ]. United States [ edit ].
Sickle cell anemia treatment
France [ edit ]. United Kingdom [ edit ]. West Asia [ edit ]. India and Nepal [ edit ]. Caribbean Islands [ edit ]. History [ edit ]. Society and culture [ edit ]. Uganda [ edit ]. Rate of sickle cell disease in Uganda [ edit ]. Misconceptions about sickle cell disease [ edit ]. Social isolation of people with sickle cell disease [ edit ]. Notes [ edit ].
References [ edit ]. National Heart, Lung, and Blood Institute. Retrieved 26 October January Archived from the original on 9 March Retrieved 8 March August The Lancet. ISSN PMC PMID American Journal of Audiology. Cleveland Clinic. Retrieved 8 May National Institute for Health and Care Excellence. July Retrieved 25 October Retrieved 25 July Archived from the original on 8 December Retrieved 8 December This article incorporates text from this source, which is in the public domain.
S2CID Annals of Medicine and Surgery. Institute for Health Metrics and Evaluation. Retrieved 17 December Textbook of clinical pediatrics 2 ed. Berlin: Springer. ISBN SCD is a genetic condition that is present at birth.
Sickle cell anemia symptoms: Sickle cell disease (SCD), also simply called sickle cell, is a group of hemoglobin-related blood disorders that are typically inherited. [2] The most common type is known as sickle cell anemia. [2] Sickle cell anemia results in an abnormality in the oxygen-carrying protein haemoglobin found in red blood cells. [2].
It is inherited when a child receives two genes—one from each parent—that code for abnormal hemoglobin. SCD is diagnosed with a simple blood test. In children born in the United States, it most often is found at birth during routine newborn screening tests at the hospital. In addition, SCD can be diagnosed while the baby is in the womb.
Diagnostic tests before the baby is born, such as chorionic villus sampling and amniocentesis , can check for chromosomal or genetic abnormalities in the baby. Chorionic villus sampling tests a tiny piece of the placenta called chorionic villus. Amniocentesis tests a small sample of amniotic fluid surrounding the baby.
Because children with SCD are at an increased risk of infection and other health problems, early diagnosis and treatment are important. People with SCD may start to have signs of the disease during the first year of life, usually around 5 months of age. Symptoms and complications of SCD are different for each person and can range from mild to severe.
Management of SCD is focused on preventing and treating pain episodes and complications. Prevention strategies include lifestyle behaviors such as maintaining adequate fluid intake and avoiding extreme temperatures and medical screenings such as transcranial Doppler TCD ultrasound screenings to identify children at increased risk of stroke.
Prevention measures also include medical interventions such as vaccines to prevent infections and blood transfusions to reduce the occurrence of stroke in persons identified to be at risk. When pain crises occur, they can be managed through various clinical strategies include medication and intravenous fluids. Additionally, several medications are available that can be taken regularly to prevent or reduce the occurrence of pain crises and other complications.
Bone marrow transplants and newly developed gene therapies are also potential treatment options for some patients.