Hematology Study Notes

Definition: Genetic disorders affecting hemoglobin structure or production.
Types:
- Sickle Cell Disease: Mutation in the beta-globin gene; causes red blood cells to assume a sickle shape, leading to pain and complications.
- Thalassemia: Reduced production of one of the globin chains (alpha or beta), leading to anemia.
  - Alpha Thalassemia: Caused by deletions; severity depends on the number of genes affected.
  - Beta Thalassemia: Caused by mutations; includes minor (mild anemia) and major (severe anemia requiring transfusions).
- Hemoglobin C Disease: Mutation causing mild hemolytic anemia and splenomegaly.
- Hemoglobin E: Common in Southeast Asia; mild anemia associated with beta-thalassemia.

Definition: Disorders affecting the blood’s ability to clot properly.
Types:
- Hemophilia: X-linked recessive disorders characterized by deficiency in clotting factors.
  - Hemophilia A: Factor VIII deficiency; leads to excessive bleeding.
  - Hemophilia B: Factor IX deficiency; similar symptoms to Hemophilia A.
- Von Willebrand Disease: Deficiency or dysfunction of von Willebrand factor, leading to bleeding problems.
- Vitamin K Deficiency: Affects synthesis of factors II, VII, IX, and X; can result from malnutrition or malabsorption.
- Disseminated Intravascular Coagulation (DIC): Acquired condition causing systemic activation of coagulation; leads to both clotting and bleeding.
- Antiphospholipid Syndrome: Autoimmune disorder increasing the risk of thrombosis.

Anemia: Condition marked by a deficiency of red blood cells or hemoglobin.
- Iron Deficiency Anemia: Most common type; caused by inadequate iron intake, chronic blood loss, or malabsorption.
- Aplastic Anemia: Bone marrow failure leading to a deficiency of all blood cell types; can be idiopathic or secondary to toxins or infections.
- Hemolytic Anemia: Increased destruction of red blood cells; can be autoimmune (e.g., autoimmune hemolytic anemia) or hereditary (e.g., hereditary spherocytosis).
Leukemia: Cancer of blood-forming tissues, leading to high numbers of abnormal white blood cells.
- Acute Lymphoblastic Leukemia (ALL): Rapid proliferation of lymphoblasts; more common in children.
- Chronic Lymphocytic Leukemia (CLL): Gradual accumulation of mature lymphocytes; more common in older adults.
- Acute Myeloid Leukemia (AML): Rapid growth of myeloid cells; affects adults and children.
Myelodysplastic Syndromes: Disorders caused by poorly formed or dysfunctional blood cells; can progress to leukemia.
Polycythemia Vera: Myeloproliferative disorder characterized by increased red blood cell mass, leading to hyperviscosity and risk of thrombosis.

Genetic disorders influence hemoglobin's structure or production.
Sickle Cell Disease results from a mutation in the beta-globin gene, causing sickle-shaped red blood cells and associated pain.
Thalassemia involves decreased globin chain production; types include:
- Alpha Thalassemia: Severity varies with deletions affecting gene count.
- Beta Thalassemia: Involves minor (mild anemia) and major (severe anemia needing transfusions) subtypes.
Hemoglobin C Disease leads to mild hemolytic anemia and spleen enlargement.
Hemoglobin E, prevalent in Southeast Asia, is associated with mild anemia linked to beta-thalassemia.

Disorders interfere with the blood's clotting ability.
Hemophilia is an X-linked disorder with two main types:
- Hemophilia A: Deficiency in factor VIII causes significant bleeding.
- Hemophilia B: Factor IX deficiency has similar bleeding tendencies.
Von Willebrand Disease results from a von Willebrand factor deficiency or dysfunction, affecting hemostasis.
Vitamin K Deficiency disrupts synthesis of key clotting factors (II, VII, IX, and X); can result from malnutrition or malabsorption.
Disseminated Intravascular Coagulation (DIC) is an acquired condition prompting systemic coagulation activation, resulting in both clotting and bleeding.
Antiphospholipid Syndrome is an autoimmune disorder heightening thrombosis risk.

Anemia refers to a deficiency in red blood cells or hemoglobin levels.
Iron Deficiency Anemia is the most prevalent form, often resulting from insufficient iron intake, chronic blood loss, or absorption issues.
Aplastic Anemia arises from bone marrow failure, leading to a lack of all blood cell types; can be idiopathic or caused by toxins/infections.
Hemolytic Anemia involves increased red blood cell destruction, with potential causes including autoimmune and hereditary conditions like hereditary spherocytosis.
Leukemia is characterized by abnormal proliferation of white blood cells.
- Acute Lymphoblastic Leukemia (ALL) predominantly affects children due to rapid lymphoblast growth.
- Chronic Lymphocytic Leukemia (CLL) gradually accumulates mature lymphocytes; primarily occurs in older adults.
- Acute Myeloid Leukemia (AML) involves swift myeloid cell growth and affects both adults and children.
Myelodysplastic Syndromes are characterized by defective or poorly formed blood cells, which may evolve into leukemia.
Polycythemia Vera is a myeloproliferative disorder marked by increased red blood cell mass, leading to hyperviscosity and thrombosis risks.