Sickle-cell disase (SCD) is a hereditary blood disorder.

• Abnormality in the Hb (hemoglobin, i.e. carries oxygen) in RBC's, causing cells to assume an abnormal, rigid, sickle-like shape
• Requires inheritance of 2 abnormal copies of the Hb gene, 1 from each parent
• Several subtypes exist, depending on the exact mutation of each Hb gene
• Presence of a single abnormal abnormal copy doesn't cause Sx, and is said to have sickle-cell trait. These patients are also referred to as carriers

• Complications can be prevented to a large extent with:
  • Vaccination
  • Preventative antibiotics
  • Blood transfusion
  • Hydroxyurea/hydroxycarbamide
• Transplant of bone marrow cells, required in a small proportion

• Severe infections
• Attacks of severe pain (sickle-cell crisis)
• Stroke
• Increased risk of death

• Sickle-cell crisis, used to describe several independent acute conditions occurring in patients with SCD. Most episodes of sickle cell crises last between 5-7 days. Although infection, dehydration and acidosis (all of which favor sickling) can act as triggers, in most cases, no predisposing cause is identified. It includes:
  • Vaso-occlusive crisis, which is caused by sickle-shaped RBC's that obstruct capillaries and restrict blood flow to an organ resulting in ischemia, pain, necrosis, and often organ damage
  • Sequestration crisis, where the spleen is frequently affected, because of its narrow vessels and function in clearing defective RBC's
  • Aplastic crisis, which is acute worsening of the patient's baseline anemia, producing pale appearance, fast HR, and fatigue
  • Hemolytic crisis, which are acute accelerated drops in hemoglobin level
• Acute chest syndrome, defined by at least 2 of chest pain, fever, pulmonary infiltrate or focal abnormality, respiratory Sx, or hypoxemia

• 300k kids are born with a form of sickle-cell disease yearly, mostly in people of African origin
• It results in 176k deaths per year, and is increasing