Haemopoiesis and Haemolytic Anaemia Flashcards
(34 cards)
Foetal haemoglobin
2 alpha and 2 gamma globin chains, should be less than 1% in adults, it is the main form before birth
HbA
2 alpha, 2 beta chains
HbA2
2 alpha, 2 delta
Definition of haemoglobinopathies
inherited disorders in haemoglobin, typically autosomal recessive
Thalassemia
Reduced or absent expression of normal globin chains
Sickle cell disease
Abnormal globin chain variants with altered function
a-Thalassemia
Humans have 4 a-globin genes, 2 on each chr16
1 deleted alpha globin gene
Silent carrier state, no symptoms, carrier of disease
2 a-globin deleted
a-Thalassemia trait, minimal or no anaemia, microcytosis and hypochromia in RBC
3 a-globin genes deleted
Haemoglobin H disease, moderately severe, microcytoc, hypochromic anaemia with target cells and Heinz bodies
4 a-globin genes deleted
Hydrops fetalis, severe, usually results in intrauterine death
Consequences of Thalassemia
Extramedullary haemopoiesis resulting in splenomegaly, hepatomegaly, impaired growth, iron overload
Thalassemia treatments
- Red cell transfusion from childhood
- Folic acid (supports erythropoiesis)
- Stem cell transplant
Sickle cell disease
Autosomal recessive resulting in mutation of beta globin gene
Why is sickle cell disease a problem?
In low oxygen state, irreversibly sickled cells that are less deformable can get stuck in small blood vessels
Symptoms of sickle cell disease
Stroke, skin ulcers, acute chest syndrome
Autoimmune haemolytic anaemias
Caused by autoantibodies binding to red cell membrane proteins, spleen recognises these as abnormal -> reduced life span of RBC
Myeloproliferative neoplasms
Overproduction of one or several blood elements with dominance of a transformed clone
Cause of myeloproliferative neoplasms
Point mutation in one copy of JAK2 gene
JAK2 mutation
Normal activated my EPO on receptor of RBC surface, mutated is activated without EPO binding
Polycythaemia
Increase in circulating RBC concentration, usually have raised haemotocrit
Polycythaemia vera
Usually in older patients, bone marrow overproduction due to genetic mutation
Clinical features of polycythaemia vera
- arterial/venous thrombosis
- splenomegaly
- gout
Secondary polycythaemia
Caused by increased levels of erythropoietin