Anemia, sickle cell

A genetic blood disorder affecting hemoglobin

Sickle cell anemia
Synonyms	N/A
Pronounce	N/A
Specialty	N/A
Symptoms	Anemia, pain crises, swelling in hands and feet, frequent infections
Complications	Stroke, acute chest syndrome, organ damage
Onset	Childhood
Duration	Lifelong
Types	N/A
Causes	Genetic mutation in the HBB gene
Risks	N/A
Diagnosis	Blood tests, genetic testing
Differential diagnosis	N/A
Prevention	N/A
Treatment	Pain management, blood transfusions, hydroxyurea, bone marrow transplant
Medication	N/A
Prognosis	N/A
Frequency	Common in people of African, Mediterranean, Middle Eastern, and Indian ancestry
Deaths	N/A

Sickle cell anemia is a genetic disorder that affects the hemoglobin within red blood cells. It is a type of sickle cell disease (SCD), which is characterized by the presence of abnormal hemoglobin, known as hemoglobin S (HbS). This condition leads to the distortion of red blood cells into a sickle shape, which can cause various complications.

Pathophysiology

Sickle cell anemia is caused by a mutation in the HBB gene on chromosome 11, which encodes the beta-globin subunit of hemoglobin. The mutation results in the substitution of valine for glutamic acid at the sixth position of the beta-globin chain. This alteration causes hemoglobin molecules to polymerize under low oxygen conditions, leading to the sickling of red blood cells.

Sickled cells are rigid and can obstruct small blood vessels, leading to vaso-occlusive crisis and ischemic damage to tissues. The sickled cells also have a shorter lifespan, resulting in chronic hemolytic anemia.

Clinical Manifestations

Patients with sickle cell anemia may experience a variety of symptoms and complications, including:

• Anemia: Due to the rapid destruction of sickled red blood cells.
• Pain crises: Episodes of severe pain due to vaso-occlusion.
• Swelling in hands and feet: Known as dactylitis, common in infants and young children.
• Frequent infections: Due to splenic dysfunction.
• Delayed growth and puberty: Resulting from chronic anemia.
• Stroke: Due to blockage of blood flow to the brain.
• Acute chest syndrome: A life-threatening complication involving the lungs.

Diagnosis

Diagnosis of sickle cell anemia is typically confirmed through:

• Blood tests: To detect the presence of sickle-shaped cells and hemoglobin S.
• Genetic testing: To identify mutations in the HBB gene.
• Newborn screening: Common in many countries to detect sickle cell disease early.

Management

Management of sickle cell anemia involves both preventive and therapeutic strategies:

• Pain management: Using analgesics and hydration during pain crises.
• Blood transfusions: To reduce the proportion of sickled cells.
• Hydroxyurea: A medication that increases fetal hemoglobin (HbF) levels, reducing sickling.
• Bone marrow transplant: The only potential cure, though it carries significant risks.

Prognosis

With appropriate management, individuals with sickle cell anemia can lead relatively normal lives, though they may experience recurrent complications. Advances in treatment have significantly improved life expectancy.

Also see

• Hemoglobinopathy
• Thalassemia
• Vaso-occlusive crisis
• Acute chest syndrome
• Bone marrow transplant