Haemoglobinopathy overview Flashcards
What makes up haemoglobin?
2 alpha chains
2 beta chains
One haem
Name 3 types of haemoglobon?
HbA
HbA2
HbF
What makes up HbA2?
2 alpha and 2 delta
What makes up HbF?
2 alpha and 2 gamma
Where are the alpha genes found?
Chromosome 16
Where are the beta genes found?
Chromosome 11
What are thalassaemias?
hereditary disorders of globin chain synthesis
What is inadequate Hb production?
Microcytic hypochromic anaemia
What is unbalanced accumulation of globin chains?
Ineffective erythropoiesis and haemolysis
What is Hb Barts hydrops fetalis?
No functional alpha genes
What is wrong with HbH?
Can’t carry oxygen
What can be seen in HbH disease when stained?
HbH bodies
How can HbH cause splenomegaly?
Extramedullary haematopoiesis
How can HbH cause jaundice?
Haemolysis
Ineffective erythropoiesis
What else can occur in HbH?
Growth retardation
Gallstones
Iron overload
What are clinical features of Hb Barts hydrops fetalis?
Severe anaemia Cardiac failure, oedema Growth retardation Severe hepatosplenomegaly Skeletal and cardiovascular abnormalities
Most die in utero
In terms of beta thalassaemia, what are the classifications?
Trait - asyptomatic or mild anaemia, low MCV/MCH
Intermedia - moderate needing occasional transfusion
major - severe, lifelong transfusion dependency
What are lab features of beta thalassaemia?
Severe anaemia
reticulocytosis, very low MCV/MCH
Microcytosis, hypochromia, anisopoikilocytosis and target cells
What spinal conditional can occur due to extramedullary haematopoiesis?
Cord compression
What are endocrine consequences of iron overload?
Impaired growth and pubertal development
Diabetes
Osteoporosis
What are cardiac consequences of iron overload?
Cardiomyopathy
Arrhythmias
What are liver consequences of iron overload?
Cirrhosis
Hepatocellular cancer
Give an example of a drug that causes iron chelating?
Desferrioxamine
What do chelators do?
Bind to iron and the complexes formed are excreted in urine/stool
Which codon in the beta globin gene substitutes glutamine to valine produsing Bs?
codon 6
What is sickle crisis?
Episodes of tissue infarction due to vascular occlusion
What is chronic haemolysis?
Shortened RBC lifespan
What is hyposplenism?
Due to repeated splenic features
What are precipitants of sickle crisis?
Hypoxia Dehydration Infection Cold exposure Stress/fatigue
What are treatments of sickle crisis?
Opiate analgesia Hydration Rest Oxygen ABx
What are the long term effects of sickle crisis?
Impaired growth Risk of sepsis Pulmonary hypertension Renal disease Avascular necrosis Leg ulcers Stroke
What are the treatments for hyposplenism?
Prophylactic penicillin
Vaccine - pneumococcus, meningococcus, haemophilus
What treatment can increase RBC turnover and increase demand?
Folic acid
What can reduce severity of sickle cell disease by inducing HbF production?
Hydroxycarbamide
