Sickle cell disease is a group of hemoglobin disorders caused by a genetic mutation.
This mutation, which shows an autosomal recessive inheritance, causes an amino acid of the beta globin chain [glutamate], to be substituted by another amino acid [valine], changing the physical properties of the whole hemoglobin molecule.
The resultant molecule is known as hemoglobin S.
This defective type of hemoglobin, aggregates together in deoxygenated states, forming rods of hemoglobin inside the red blood cells.
These rods then change the shape of red cells, making them look like pointed sickles.
Hence the name sickle cell disease.
These cells are more rigid and thicker than the normal cells; therefore, they cannot flow smoothly through small blood vessels.
This leads to a vast array of complications throughout the body.
Also, in hypoxic and dehydrated conditions, aggregation of hemoglobin S markedly increases, further increasing the viscosity of blood.
In addition to other features of the disease, sickle cells die very early.
Their lifespan is only around 10 days in contrast to the 72-day lifespan of normal red blood cells.
This leads to extensive hemolysis leading to the condition known as sickle cell anemia.
If a person receives the mutation from only one of the parents, he will have just enough healthy red blood cells needed for normal circulation.
These people are called sickle cell carriers.
But if both genes are mutated in someone, he can get the full blown disease.
Features
Sickle cell carriers do not present with health problems unless they are exposed to extreme hypoxic conditions.
Patients with sickle cell disease can present at any age, but they are protected in the first six months of their lives due to the presence of fetal hemoglobin, which is an efficient oxygen transporter.
But after that, sickle cells tend to clog up in the small vessels and break down, lead to features like;
The haemoglobin level will surely be low as the patient is in an anemic state.
The blood picture will show sickle cells and target cells.
Howell–Jolly bodies, which is a feature of splenic atrophy, may also be evident in the blood smear.
Some countries carry out screening tests for sickling at birth, which is an effective strategy for identifying patients at an early stage.
Protein electrophoresis is another test that can be used to check if HbS is present in a patient’s blood.
- Full blood count
- Peripheral blood smear
- Screening tests for newborns
- Protein electrophoresis
Treatment
The known trigger factors for crises like high altitudes and dehydration should be avoided, while maintaining good hygiene and nutrition, taking folic acid supplements if needed.
Vaccines for encapsulated bacteria are beneficial as the spleen might get affected.
Effective medical management options for the disease include hydroxyurea to increase fetal hemoglobin concentrations, opioids for pain management, and antibiotics for infections.
Sickle cell crises are managed with warmth and rehydration by oral fluids or saline until they resolve.
Severe cases of sickle cell anemia, however, might require blood transfusions or bone marrow transplants.
No responses yet