Haemoglobinopathies Flashcards
What are haemoglobinopathies?
A group of inherited disorders characterised by the production of structurally abnormal haemoglobin or reduced synthesis of one or more globin chains.
What are the two main classifications of haemoglobinopathies?
- Thalassaemias
- Structural haemoglobin variants
What is the primary result of thalassaemias?
Imbalanced globin chain production leading to ineffective erythropoiesis and chronic haemolytic anaemia.
What is an example of a structural haemoglobin variant?
Sickle cell disease.
What type of genetic disorder is thalassaemia?
Autosomal recessive.
What is the normal structure of haemoglobin?
Consists of 2 alpha-globin and 2 beta-globin chains.
What happens to globin chain production in thalassaemia?
Globin genes are absent or mutated, leading to reduced ability to produce globin chains.
What are the universal clinical features of thalassaemia?
- Microcytic anaemia (low MCV)
- Fatigue
- Pallor
- Jaundice
- Gallstones
- Splenomegaly
- Poor growth and development
What investigations are performed for thalassaemia?
- FBC
- Haemoglobin electrophoresis
- DNA testing
What causes iron overload in thalassaemia?
- Increased iron absorption
- Blood transfusions
What are the types of alpha-thalassaemia?
- Alpha thalassaemia trait
- Haemoglobin H disease
- Alpha thalassaemia major (hydrops fetalis)
What is a severe form of beta-thalassaemia?
Beta thalassaemia major, characterised by severe anaemia and failure to thrive in early childhood.
What is sickle cell disease?
A group of genetic disorders (autosomal recessive) with deformed red blood cells.
What is the most common and severe form of sickle cell disease?
Sickle cell anaemia.
What triggers the polymerisation of haemoglobin S (HbS) in sickle cell disease?
Physiological stress such as hypoxia, dehydration, infection, cold temperature, and acidosis.
What is a vaso-occlusive crisis in sickle cell disease?
A type of sickle cell crisis where sickled red blood cells obstruct capillaries, causing pain and ischaemia.
What are the signs and symptoms of acute chest syndrome in sickle cell disease?
- Fever
- Cough
- Tachypnoea
- Dyspnoea
- New-onset hypoxia
What is an aplastic crisis in sickle cell disease?
Temporary cessation of erythropoiesis leading to severe anaemia, usually triggered by parvovirus B19.
What preventative measures are recommended for sickle cell disease management?
- Avoiding triggers like cold temperature and dehydration
- Antibiotic prophylaxis
- Vaccinations
- Folic acid supplements
What is the purpose of hydroxycarbamide in sickle cell disease management?
Increases HbF production and reduces the proportion of HbS.
What are the abnormal features associated with beta-thalassaemia major?
- Frontal bossing
- Enlarged maxilla
- Depressed nasal bridge
- Protruding upper teeth
Pathophysiology of thalassaemia
- reduced globin chains
- fragile red cells break down easily (haemolytic anaemia)
- spleen collects destroyed red cells (splenomegaly)
What is priapism?
Relating to sickle cell disease
- trapping of blood in penis
- painful, persistent erection
- urological emergency, aspirate blood
Features of hyposplenism on blood films
- target cells
- Howell-jolly bodies
General management of sickle cell disease
Prevention:
- avoid triggers
- prophylactic penicillin V
- vaccinations
- folic acid supplements
Medical:
- blood transfusions
- hydroxycarbamide
- bone marrow transplant
