Thalassaemia Flashcards
What is beta-thalassaemia.
Most common autosomal recessive inherited haematological disorder.
Where is beta-thalassaemia most common. (3)
Mediterranean.
Middle East.
Asia.
What is the pathogenesis of beta-thalassaemia.
Decreased beta-globin production, leading to chronic anaemia.
What does beta-thalassaemia lead to.
Chronic anaemia.
What sort of anaemia is present in beta-thalassaemia.
Microcytic anaemia.
What is seen in patients who are homozygous for beta-thalassaemia. (4)
Failure to thrive.
Severe anaemia (from 3 to 6 months).
Splenomegaly.
Bone hypertrophy (secondary to extramedullary haemopoiesis).
What is seen in patients who are heterozygous for beta-thalassaemia. (3)
Usually asymptomatic.
Mildly anaemic.
Decreased MCV.
What are the complications of beta-thalassaemia. (2)
Secondary haemosiderosis (from repeated blood transfusions). Endocrine disease.
What are the clinical divisions of beta-thalassaemia. (3)
Thalassaemia minor.
Thalassaemia intermedia.
Thalassaemia major.
What characterises thalassaemia minor.
A symptomless heterozygous carrier state.
May have mild manageable anaemia.
The anaemia may worsen during pregnancy.
What characterises thalassaemia intermedia. (2)
A moderate anaemia.
Not requiring regular transfusions.
What characterises thalassaemia major.
Severe anaemia requiring regular transfusions.
What distinguishes thalassaemia minor from iron deficiency anaemia on blood tests. (2)
Serum ferritin and iron stores are normal.
What is another name for thalassaemia major.
Cooley’s anaemia.
What are some physical signs seen in thalassaemia intermedia. (6)
Splenomegaly.
Bone deformities.
Recurrent leg ulcers, gallstones and infections.
They may be iron overloaded despite the lack of regular blood transfusions.
What are some physical signs seen in thalassaemia major. (4)
Most children affected by homozygous Beta-thalassaemia present during the first year of life with:
Failure to thrive.
Recurrent bacterial infections.
Severe anaemia from 3-6months.
Extramedullary haemopoiesis that leads to hepatosplenomegaly and bone expansion - giving a classic thalassaemic face.
What is seen on the skull Xrays of a child with thalassaemia major.
The characterisitc ‘hair on end’ appearance of bony trabeculation, as a result of the expansion of the bone marrow into cortical bone.
What is the cause of beta-thalassaemia.
Usually caused by point mutation in beta-globin genes on Chromosome 11.
What is absent or abnormal in beta-thalassaemia.
There is either decreased beta chain production, or its absence.
What is MRI used for in beta-thalassaemia.
To monitor myocardial siderosis from iron overload.
When does thalassaemia major usually present.
In the first year of life.
What is necessary in thalassaemia major.
Lifelong blood transfusions.
What is a complication with the treatment for thalassaemia major.
Transfusions result in iron overload/deposition.
This is seen after approximately 10 years and presents as endocrine failure, liver disease and cardiac toxicity.
What is seen on the blood film of a patient with thalassaemia major. (3)
Very hyperchromic, microcytic cells.
Target cells.
Nucleated RBCs.
How many alpha thalassaemia genes are there.
There are two separate alpha globin genes on each chromosome 16.
Ie, there are 4 genes.
What is the predominant mechanism for alpha thalassaemia.
Gene deletions.
What occurs if there is deletion of all four alpha genes.
Bart’s hydrops - death in utero.
What occurs if there is deletion of three alpha genes.
HbH disease.
What are the characteristics of HbH disease. (2)
There may be moderate anemia.
Features of haemolysis (hepatosplenomegaly, jaundice, leg ulcers).
What is seen on the blood film of a patient with HbH.
There is formation of Beta4 tetramers due to excess beta chains.
What are the characteristics of HbA. (2)
Asymptomatic carrier state.
Low MCV.
What occurs if there is deletion of one alpha globin gene.
There is a normal clinical pictures.
What is the difference between alpha and beta thalassaemias. (2)
In alpha thalassaemia there are excess beta chains.
In beta thalassaemia, there are excess alpha chains.
