Haemoglobinopathy/thalassaemia in pregnancy

Question 1

What is the definition of a thalassaemia

Answer 1

• imbalance in globin chain production
  e.g. beta thalassaemia - mutations in beta gene resulting in free alpha chains
  Red cells indices - reduced MCV and MCH

Question 2

what is the definition of a haemoglobinopathy?

Answer 2

point mutation in the alpha or beta gene resulting in a structurally abnormal Hb
red cell indices - normal MCV and MCH

Question 3

List 4 indications for testing for haemoglobinopathy

Answer 3

• to confirm a provisional diagnosis
• to explain a haematological abnormality
• to permit genetic counselling of prospective counselling
• to identify abnormality in pre clinical phase

baby doesn’t develop a beta globin gene until 6/12 of life

Question 4

what is the pathophysiology of beta thalassaemia morbidity?

Answer 4

• reduced or absent beta globin chains
• lots of free alpha globin chains
• alpha globin chains are less soluble than beta globin chains
• insoluble therefore precipitate on the surface of the RBC resulting in haemolysis = anaemia
• other mechanism is the Alpha chains precipitate on the erythroid precursor cells results in ineffective erythropoiesis and cell death = anaemia
• increased iron absorption as a result of anaemia results in iron loading e.g. in cardiac muscle leading to cardiomyopathy
• bone marrow expands to accommodate for increase in erythropoietin which results in skeletal changes and a hyper metabolic state

Question 5

what is the inheritance pattern of sickle cells disease

Answer 5

autosomal dominant HbSS