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Haemoglobinopathies. - are a group of inherited conditions with abnormalities of the Hb. - Haemoglobin consists of a group of four molecules, each of which as a haem unit made up of an iron porphyrin complex and a protein or globin chain.
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Haemoglobinopathies • - are a group of inherited conditions with abnormalities of the Hb. • - Haemoglobin consists of a group of four molecules, each of which as a haem unit made up of an iron porphyrin complex and a protein or globin chain. • A total of 97% of adult Hb (HbA) has two α- and two β-chains and the remaining 3% is composed of two α- and two δ-chains.
-Fetal Hb (HbF) has two α- and two γ-chains, gradually replaced by the β-chain by around the age of 6 months. • -The type of globin chain is genetically determined and defective genes lead to the formation of abnormal haemoglobin.
-This may be as a result of impaired globin synthesis (thalassaemia syndromes) or from structural abnormality of globin (haemoglobin variants such as sickle cell anaemia). • - Haemoglobinopathies mainly affect people from Africa, West Indies, Asia, the Middle East and the eastern Mediterranean and the theory is that the carrier state offers some protection against malaria ).
Thalassaemia • -different types of thalassaemia depending upon which haemoglobin chain has been affected: α-chains are formed by two genes from each parent whereas β-chains are formed by one gene from each parent. In α-thalassaemia, the production of α-globin is deficient and in β -thalassaemia the production of β-globin is defective.
α-thalassaemia major: Four defective α genes. This type is also known as Hb Bart's. • It presents as severe non-immune intrauterine haemolytic anaemia • . As a result the fetus becomes oedematous: known as hydrops fetalis/Hb Bart's hydrops, which is usually fatal
β-thalassaemia • One defective β gene is inherited. individual presents with mild anaemia, a low MCV and MCH, but is clinically asymptomatic.
β-thalassaemia intermedia: This type presents with high levels of HbF which can fluctuate, resulting in anaemia upon which symptoms usually develop when the haemoglobin level remains below 7.0 g/dl, a very low MCV and MCH, splenomegaly and variable bone changes. • The dependency on blood transfusion
β-thalassaemia major: As a result, the individual presents with severe haemolytic anaemia, a very low MCV and MCH, and hepatosplenomegaly, such that they are chronically dependent on frequent blood transfusions
Diagnosis : • full blood count that would reveal a low mean corpuscular haemoglobin (MCH <27 pg) and a low mean cell volume (MCV <75 fl) • bone marrow examination would reveal microcytic, hypochromic red blood cells • haemoglobin analysis would reveal elevated HbA2 levels • Pre-conception care is important and genetic counselling may be required, especially if there is inter-marriage of cousins. There is a 1 in 4 chance of a baby inheriting a major condition if both parents are carriers
-DNA analysis of chorionic villi and fetal blood sampling with termination of pregnancy. • -Antenatal care should be provided within an obstetric unit where the woman can be assessed within a combined clinic with a haematologist in afendance. • - The treatment would entail regular assessment of FBC and serum ferritin. • - Iron is prescribed only if serum ferritin levels are low as there is a risk of iron overload, which may lead to congestive cardiac failure.
- investigations to assess cardiac function. Folic acid deficiency must be treated and dietary advice given by the midwife . • woman has thalassaemia major she is at risk of pre-term labour, which might be iatrogenic, as well as both maternal and fetal hypoxia in labour. • - If the woman has any bone deformities, caesarean section may be necessary. • continuous fetal monitoring in labour and strict monitoring of blood pressure and fluid balance. Due to the risk of haemorrhage, it would be wise for the midwife to facilitate active management of the third stage of labour.
postnatal period, the woman should be observed for signs of infection and hemorrhage and any wound should be inspected for signs of poor healing. • the anemia might worsen following the birth if the baby and tiredness could also predispose to depression. • -The baby will require paediatric assessment appointments should be made to monitor growth and development as well as determine the baby's thalassaemia status.
