Anemia

Sickle cell disease

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Sickle cell disease
foto de Miguel Cabrero de Cabo Ph.D.
Written by

Miguel Cabrero de Cabo Ph.D.
Medically reviewed by our Medical staff

Last update: 26-08-2021

How else can it be called?

  • Sickle cell anemia

  • HbS disease

  • Hemoglobin S disease

  • SCD

  • CIE-9: 282.6

  • CIE-10: D57

What is sickle cell disease?

Sickle cell disease is a genetic and inherited blood disorder that affects hemoglobin morphology and caused red blood cells with a sickle or crescent shape.

Hemoglobin is an essential molecule of the red blood cells (or erythrocytes). The main purpose of hemoglobin is to transport oxygen through the bloodstream.

Normal red blood cells (RBCs) have a biconcave disc shape. The abnormal hemoglobin produced in this disorder, called hemoglobin S, causes the presence of red blood cells more fragile and shaped like sickles or crescents.

What causes sickle cell disease?

Sickle cell disease is a hereditary genetic disorder caused by the mutation of the HBB gene (11p15.4) located on chromosome 11.

It is an autosomal recessive disorder. It means that it requires both altered copies of the gene, one from each parent, to develop the disease.

People who only have mutated gene will carry the disease with no symptoms. Carriers may pass on the condition to his or her own children.

The mutation causes an abnormally develop of the red blood cells. The red blood cells are stiff and sticky and they may lead to anemia and obstruction of blood vessels that may result in clinical manifestations such as pain crisis, necrosis, bacterial infections, etc.

What incidence does it have?

Sickle cell disease is one of the most common genetic disorders worldwide, which affects approximately 50 million people.

It is more common in equatorial Africa, Mediterranean, India, and the Middle East. It is most frequently seen in black people.

Carriers of the sickle cell trait have some resistance against malaria. They have a better survival rate against this infectious disease.

What are the main symptoms of sickle cell disease?

The symptoms are very diverse. There may be people asymptomatic for life, while others have repeated episodes of severe pain (crises) since childhood that require frequent hospitalization.

The symptoms are a consequence of the obstruction of blood vessels and may affect any part of the body. The obstruction may produce ischemia (lack of oxygen) of the affected area, with very intense pain.

The most common complications are:

  • Chronic anemia
  • Severe pain crises
  • Necrosis
  • Bacterial infections (pneumonia, meningitis, osteomyelitis, bacteremia)
  • Enlarged spleen (sometimes requires spleen removal)
  • Stroke (rare)
  • Heart attack (rare complication)
  • Visual impairment (in case of retinal artery occlusion)
  • Priapism (prolonged and painful erection, it is a medical emergency)
  • Pregnancy complications

It can also lead to long-term complications, such as:

  • Chronic pain
  • Heart and lung problems
  • Neurological disorders
  • High blood pressure and kidney failure
  • Chronic ulcers
  • Visual impairments

How can it be detected?

Molecular genetic testing can be performed to detect the presence of the mutated HBB gene.

It is important to study the rest of the family to avoid further transmission to the offspring.

A newborn screening for sickle cell disease is recommended to detect the disorder as soon as possible.

What is the recommended treatment?

Generally, patients tend to be asymptomatic. Those who suffer pain crises and associated complications require hospitalization.

When symptoms are present, the course of treatment is:

  • Intravenous hydration
  • Analgesics and narcotics (morphine) to relieve the pain
  • Antibiotics (if there are bacterial infections)
  • Blood transfusions (in case of severe anemia)

How can I prevent it?

Sickle cell anemia can be prevented through molecular genetic testing of the family and parents to avoid passing the mutation to the offspring.

Other recommendations include:

  • Healthy balanced diet and proper hydration.
  • Preventive treatment with hydroxyurea (for those who suffer frequent crises).
  • Pneumococcal and Haemophilus Influenzae vaccines (for those who have had their spleen removed).
Medically reviewed by our Medical staff on 26-08-2021

Bibliography

  • UpToDate “Overview of the clinical manifestations of sickle cell disease” Elliott P Vichinsky. Available on: https://www.uptodate.com
  • Atlas of Genetic Diagnosis and Counseling (3rd Ed) 2017, Harold Chen, ISBN: 978-1-4939-2400-4, Pag. 2601.
  • First Aid for the Basic Sciences: Organ Systems (3rd Ed) 2017, Tao Le, William L. Hwang, Vinayak Muralidhar, Jared A. White and M. Scott Moore, ISBN: 978-1-25-958704-7, Pag. 284.
  • Basic Pathology (10th Ed) 2018, Vinay Kumar, Abul K. Abbas, Jon C. Aster, ISBN: 978-0-323-35317-5, Pag. 445.

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