Virtual Medical Centre

Sickle Cell Disease

• What is Sickle Cell Disease?
• Who gets Sickle Cell Disease?
• Predisposing Factors
• Progression
• Probable Outcomes
• How is Sickle Cell Disease Diagnosed?
• How is Sickle Cell Disease treated?
• Sickle Cell Disease References
• Drugs/Products Associated with Sickle Cell Disease

What is Sickle Cell Disease?

Sickle cell anaemia is a structural abnormality of the haemoglobin chain in blood.

Who gets Sickle Cell Disease?

The main pathology of the sickle cell syndrome is an abnormality of the haemoglobin gene, the oxygen carrying protein of the bloodstream. The sickle cell form of this gene is most commonly carried by the African population, with approximately 8% of African Americans carrying the sicle cell disease gene. In other regions such as India and the Middle East, different abnormalities exist in the haemoglobin gene, causing a similar pattern of disease.

The gene is relatively uncommon amongst caucasian populations.

Predisposing Factors

Predisposing factors for the incidence of sickle cell syndromes include:
1. Family History - As this condition cannot be acquired, family history is the most important risk factor in the development of a sickle cell syndrome.
2. Race - The condition is more common in negro populations.
3. Local prevalence of malaria- As sickle cell disease protects against the development of malaria, the process of natural selection has increased the prevalence of sickle cell disease to 30% in some regions.

Progression

Sickle cell syndromes are notable for the vast difference in severity between patients with different forms of the disease. The condition is universally inherited, yet its course may be mild and asymptomatic, or severe and disabling.

The main disease process occurring in sickle cell disease is the sudden destruction of red blood cells by "sickling." The red blood cells of the patient with sickle cell anaemia are unstable, and take on a sickled non-functional form when the patient is subject to ceratin disease or physical stress.

Sickle cell anaemia varies from a mild symptomatic disorder to a severe haemolytic anaemia and recurrent severe painful crises. The variation in disease severity relates to the nature of the genetic mutation, which differs between each form of the disease. The condition may present in childhood with anaemia and mild jaundice.

The hand-and-foot syndrome due to infarcts of small bones is quite common in children and may result in digits of varying lengths.

In the older patient, blood vessel may be occluded owing to sickling of blood cells in the small vessels of any organ.

Long-term problem associated with the disease include:
(1) Susceptibility to infections, particularly to Streptococcus pneumoniae, which can cause a fatal meningitis or pneumonia. Bone infection can occur, often due to Salmonella;
(2) Chronic leg ulcers due to poor blood flow to the limbs with sickle cell obstruction;
(3) Gallstones- pigment stones from persistent red blood cell destruction;
(4) Degeneration of bone, particularly of the hips;
(5) Blindness due to retinal attachment and/or retinal disease; and
(6) Chronic renal disease.