Haemoglobinopathies Flashcards
alpha gene for global chain is present on which chromosome
chromosome 16
beta gene is present on which chromosome
chromosome 11
after how long is adult level of Hb reached?
6-12 months
problems do not manifest until 6-12 months
haemoglobinopathies are autosomal recessive or dominant?
Recessive
2 main groups?
- thalassemia (decreased rate of global synthesis)
- Sickle cell (structural Hb variant)
how to distinguish between alpha thalassemia trait and iron deficiency?
in alpha thalassemia- ferritin will be normal
HbH disease
- only one working alpha gene
- anaemia
- very low MCV and MCH
- excess Beta chain form tetramers (beta 4)
presentation
- Jaundice
- splenomegaly
there may be a need for transfusion
common in South east Asia
Hb Barts Hydrops Foetalis Syndrome
- no alpha gene
- no production of HbF and HbA
- tetramers of Hb Parts (gamma4) and HbH
clinical presentation
- profound anaemia
- cardiac failure
- growth retardation
- severe hepatosplenomegaly
- skeletal and cardiovascular abnormalities
- almost all die in utero
what is diagnostic of beta thalassemia trait?
rasied HbA2
Beta thalassemia major
- presents when HbF falls (6-24 months)
presentation
- pallor
- failure to thrive
- hepatosplenomegaly
- skeletal changes
- organ damage
- on analysis only HbF present and no HbA
- extra medullary haematopoiesis can cause cord compression
management of Beta thalassemia major
- regular transfusion to maintain Hb
- BM transplant before development of complications
what is the main cause of mortality in beta thalassemia major
- iron overload
what happens if there is iron overload?
- endocrine dysfunction
- cardiac disease
- liver disease
management of iron overload
iron cheating agents (desferrioxamine)
Sickle cell trait (HbAS)
- asymptomatic carrier state
- may sickle in severe hypoxia
- mainly HbA
- HbS is less than 50%
