Swelling of hands & feet, fatigue, irritability: Everything you need to know about sickle cell disease
The symptoms aggravate due to dehydration, infection and hypoxia.
Sickle cell disease (SCD) is one of the most prevalent inherited blood disorders in the world. The defect arises from a single mutation in the gene, encoding beta-globin chain of hemoglobin (the protein in red blood cells (RCB) that helps in carrying oxygen throughout the body). If both the beta-globin chains are mutated then the condition is called as sickle cell anaemia (SCA), which is the most common disorder in the SCD group.
India alone is home to about 150,000 patients with sickle cell disease and about 88% of SCA cases in Asia. Cases are predominantly found in central India, and northern Kerala and Tamil Nadu, which is also known as the sickle belt of India.
The abnormal hemoglobin leads to a change in the shape of RCB from normal discoid to sickle or crescent-shape.
The symptoms get exacerbated in the presence of dehydration, infection and hypoxia. This change in shape makes the cells stiff and sticky leading to formation of clumps in the blood vessels and obstruction of blood flow.
This results in accelerated destruction of RBC leading to anaemia, episodes of extreme pain as well as chronic damage to vital organs.
Signs And Symptoms
The symptoms usually show in children after six months of age. Children with SCA inherit two copies of the sickle cell gene- one from each parent while a sickle cell trait inherits only one copy of the sickle cell gene from one parent. Such a person can pass on the gene to his or her offspring but remains asymptomatic unless they face severe deprivation of oxygen or severe dehydration.
The disease is common in communities where consanguineous marriages are prevalent. The chances of both mother and father carrying the abnormal gene are significantly increased if they have descendants of a common ancestor.
Almost all major symptoms are the direct result of the abnormally sickle-shaped RCB blocking the flow of blood. Frequently seen signs and symptoms include:
- Anaemia occurs due to short RBC lifespan. It leads to fatigue, irritability, poor growth and development, etc.
- Pain crisis is the most common symptoms of SCA. Periodic episodes of pain occur in chest, abdomen, bones and joints due to blockage of tiny blood vessels by sickle-shaped RBC. Painful swelling of hands and feet also occur. Frequency of pain crises can vary from individual to individual, and may even need hospitalisation for treatment.
- The disease damages the spleen at a very early age, which impairs the body's immune system, making young children extremely vulnerable to bacterial infections.
- Delayed growth
- It causes vision problems due to blockage in the blood vessels.
- Pooling of blood in spleen (splenic sequestration) is also a symptoms which can be fatal.
It is also associated with numerous complications such as stroke, and acute chest syndrome characterised by sudden chest pain, breathing difficulty, high blood pressure in the blood vessels that supply to the lungs (pulmonary hypertension), organ damage such as liver and kidney, blindness, gall stones, leg ulcers, bone and joint damage and painful penile erection (priapism) leading to impotence.
Genetic counselling is of paramount importance as the disease has no permanent cure except bone marrow transplant. In areas with high prevalence of SCA, awareness programs should be implemented and routine screening should be done to detect carrier status.
Marriage between two carriers is discouraged. When there is a family history of SCA or both parents are carriers, prenatal diagnosis can be done when using DNA analysis of fetal cells through procedures such as amniocentesis and chorionic villus sampling. Screening of newborn is important to reduce morbidity and mortality of SCD patients.
Diagnosis and Treatment
Diagnosis can be made through examination of a blood smear showing the characteristic sickle cells. Confirmatory diagnosis is through quantification of the types of hemoglobin present using hemoglobin electrophoresis.
SCA patients need specialist care throughout their lives in order to improve quality of life. The treatment measures include:
- Prevention of painful episodes by drinking plenty of fluids and staying warm.
- Pain crisis will require hospitalisation and treatment with intravenous pain killers and hydration.
- The risk of infections can be reduced by taking daily antibiotics and vaccination.
- Any fever needs to be treated urgently with antibiotics.
- Blood transfusion may be needed if severe anaemia develops. Sometimes regular blood transfusion may be needed in case of worsening symptoms.
- Hydroxyurea can be taken orally. This can reduce frequency of pain crisis and need of regular blood transfusions.
- Using a special ultrasound machine (transcranial), children with a higher risk of stroke can be diagnosed early.
- Sometimes a red blood cell exchange is performed. This process removes some of the sickle blood cells and replaces them with normal (non-sickle) blood cells.
- The only definitive cure is bone marrow transplant in which the bone marrow of a healthy donor replaces the diseased bone marrow of the patient.
(The author is Senior Consultant & Head Pediatric Hematology, Oncology and Blood & Marrow Transplantation, Mazumdar Shaw Cancer Centre, Narayana Health City)