Sickle cell disease is a group of red blood cell disorders usually inherited from the parents. It is inherited in an autosomal recessive manner. It is due to an abnormality in the oxygen-carrying protein hemoglobin (hemoglobin S) found in red blood cells. This leads to sickling of the red blood cells resulting in early death of the cell or obstruction of the blood vessels.
Sickle cell disease in children begins to manifest after the age of 5-6 months. This is because the fetal hemoglobin in the baby which has a high oxygen carrying capacity compensates for the abnormal sickle red blood cell.
More than 300,000 babies are born with severe forms of hemoglobinopathies worldwide each year. 75 percent of all patients with sickle cell disease live in Sub-Saharan Africa while Nigeria alone accounts for more than 100,000 new births every year. It is also commonly found in tribal regions of India and the Middle-East. SCD affects approximately one in every 300 – 500 African American newborns.
Normal red blood cells are elastic and easily pass through blood vessels. However, sickle red blood cells have lost their elasticity and get stuck in red blood cells leading to ischemia. The sixth amino acid glutamate, in the hemoglobin structure is replaced by valine which leads to change in structure and function of the red blood cell.
The abnormality is usually inherited from the parents in an autosomal recessive manner. A person can be a heterozygous, whereby the child is just a carrier of the sickle gene. He/swhe has inherited the abnormal gene from just one parent but they don’t manifest the disease (AS,AC). A person is homozygous when the child has inherited the abnormality from both parents and will thus manifest the disease.
There are different forms of the homozygous disease and they include;
- Hemoglobin SS
- Hemoglobin SC
- Hemoglobin Sβ0 thalassemia
- Hemoglobin Sβ+ thalassemia
- Hemoglobin SD
- Hemoglobin SE
- Sickle cell hemoglobin C disease is usually less severe.
Signs and symptoms
Sickle cell disease causes significant morbidity and mortality. It begins to manifest in early childhood. Some of the symptoms they manifest with include;
- Bossing of the skull; this is a prominent, protrusion of the forehead that’s also often associated with a heavy brow ridge. It results due to erythropoiesis (red blood cell formation) outside the long bones.
- Dactylitis; which is the painful swelling of the dorsal part of the hands and foot.
- Bone pain; affects long bones of the limbs usually due to bone marrow infarction (death).
- Anaemia; is due to the rapid breakdown of red blood cells in the child. It is usually chronic. Normal red blood cells last for 90-120 days while sickle cells last for just 10-20 days. There is also pooling of the abnormal red blood cells in the spleen where they are also destroyed.
- Growth retardation/being underweight
- Delayed sexual maturation
- Limb length discrepancy; the finger to finger length of the child is usually longer than the length of the body.
- Splenic enlargement; this is due to the pooling of blood cells into the spleen. It can be life threatening.
- Infection; sickle cell disease patients are prone to being infected by encapsulated bacteria especially Streptococcus pneumonia.
- Acute and chronic pain: due to the abnormal nature of their red blood cells, they block the blood vessels leading to insufficient blood flow to the tissue and associated death. This is a major cause of crisis in sickle cell patients.
- Acute chest syndrome: Young children present with chest pain, fever, cough, tachypnea, leukocytosis, and pulmonary infiltrates in the upper lobes
- Pulmonary hypertension: Increasingly recognized as a serious complication of sickle cell diseases. It is characterized by high blood pressure in the lungs due to damage to the pulmonary arteries by the sickle red blood cells.
- Avascular necrosis of the femoral or humeral head: This is due to vascular occlusion of the head of the femoral or humeral bone by the sickle cells.
- CNS involvement: the most severe manifestation is stroke
- Eyes: they can have ptosis, retinal vascular changes and proliferative retinitis
- Heart: Dilation of both ventricles and the left atrium
- Gall stones
- Priapism; obstruction of the blood vessels of the penis by the abnormal sickle cells can prevent drainage of blood from the penis. It requires prompt management so as to prevent damage to the penile tissue.
- Leg ulcers are a chronic painful problem
Sickle cell disease is a life-long disease that requires continuous care and management. The diagnosis of the disease should be confirmed in the laboratory.
- The disease can be cured by a bone marrow transplant from a person not carrying the disease (AA). However, bone marrow transplants are difficult to obtain because of the specific HLA typing necessary.
- Folic acid supplements; daily supplements of folic acid should be taken for life to aid in the formation of red blood cell from the bone marrow.
- Adequate hydration; dehydration in sickle cell patient increases the viscosity of the blood leading to increased chances of blood vessel obstruction (crisis).
- Blood transfusion; this can be given to reduce the chances of complication in sickle cell patients. It also reduces the amount of sickle cells in the child’s body.
- Vaccination; splenic damage which occurs in sickle cell patients increases their chances of having infections caused by encapsulated bacteria. Therefore, they should be vaccinated against common encapsulated organisms such as pneumococcal spp.
- Malaria prophylaxis; sickle cell is prevalent in malaria endemic regions. The malaria parasite leads to breakdown of the few red blood cells that they have. Malaria is the most common cause of crises in them. They are therefore given malaria prophylaxis for life.
- Pain medication; when they have crisis they are given pain medication such as non steroidal anti-inflammatory, opioid depending on the severity of the pain.
- Hydroxyurea can also be given to them as it helps stimulate the body to make fetal hemoglobin, the type of hemoglobin that newborns have and lowers white blood cells that can contribute to slowing blood flow.
- They should avoid cold weather as this will slow down blood flow in the blood vessels and lead painful crises due to infarction.
- Routine medical checkup by a specialist is important in the management of sickle cell disease.
About 90% of people survive to age 20, and close to 50% survive beyond the fifth decade.
This disease can however be prevented. People who are both carriers of the disease shouldn’t have children together. It is important we prevent this disease.