Sickle Cell Anemia

Definition

Sickle cell anemia is an inherited blood disorder characterized by red blood cells that become sickle or crescent-shaped. This abnormal shape causes the cells to get stuck in small blood vessels, leading to periodic episodes of pain, organ damage, and other complications.

5 Must Know Facts For Your Next Test

1. Sickle cell anemia is caused by a genetic mutation that results in the production of abnormal hemoglobin, known as hemoglobin S.
2. Individuals with sickle cell anemia inherit two copies of the sickle cell allele, one from each parent.
3. The sickle cell mutation is most common in parts of the world where malaria is or was prevalent, as it provides some protection against the disease.
4. Sickle cell anemia can lead to a variety of complications, including pain crises, acute chest syndrome, stroke, and organ damage.
5. Early diagnosis and comprehensive medical care, including hydroxyurea and blood transfusions, can help manage the symptoms and complications of sickle cell anemia.

Review Questions

• Explain how the genetic mutation responsible for sickle cell anemia is inherited and how it leads to the characteristic sickle-shaped red blood cells.
  • Sickle cell anemia is an autosomal recessive disorder, meaning an individual must inherit two copies of the sickle cell allele, one from each parent, to develop the condition. The genetic mutation responsible for sickle cell anemia occurs in the hemoglobin gene, causing the production of abnormal hemoglobin known as hemoglobin S. This abnormal hemoglobin causes the red blood cells to become sickle or crescent-shaped, rather than the normal round, flexible shape. The sickle-shaped cells can get stuck in small blood vessels, leading to the characteristic pain crises and other complications associated with sickle cell anemia.
• Describe the relationship between sickle cell anemia and malaria, and explain how this relationship has influenced the prevalence of the sickle cell mutation in certain geographic regions.
  • The sickle cell mutation provides some protection against malaria, a life-threatening parasitic disease that was historically prevalent in parts of Africa, the Mediterranean, and the Middle East. Individuals who carry one copy of the sickle cell allele (heterozygous) have a reduced risk of severe malaria, as the sickle-shaped red blood cells make it more difficult for the malaria parasite to infect and replicate within the cells. This evolutionary advantage has led to a higher frequency of the sickle cell allele in populations where malaria was or is endemic, such as sub-Saharan Africa. However, individuals who inherit two copies of the sickle cell allele (homozygous) develop sickle cell anemia, a serious and potentially life-threatening condition.
• Evaluate the importance of early diagnosis and comprehensive medical care in the management of sickle cell anemia, and discuss how advancements in treatment have impacted the prognosis and quality of life for individuals with this disorder.
  • Early diagnosis of sickle cell anemia is crucial, as it allows for prompt initiation of comprehensive medical care and management strategies. With early intervention, individuals with sickle cell anemia can receive treatments such as hydroxyurea, which can help reduce the frequency and severity of pain crises, as well as blood transfusions to prevent complications like stroke. Advancements in medical care, including the development of new therapies and improved management of complications, have significantly improved the prognosis and quality of life for individuals with sickle cell anemia. While the disorder still presents significant challenges, the availability of comprehensive care has enabled many individuals with sickle cell anemia to lead more active and fulfilling lives, with a reduced risk of life-threatening complications and a greater ability to manage their condition effectively.

Related terms

Hemoglobin:

The iron-rich protein in red blood cells that carries oxygen throughout the body.

Recessive Inheritance: A pattern of inheritance where an individual must inherit two copies of a recessive allele, one from each parent, to express the associated trait or disorder.

Genetic Mutation: A permanent change in the DNA sequence that can alter the function or expression of a gene.