Haematology summray 7

Chapter 7 in Haematology (Genetic disorder of haemoglobin) summary

 

-Genetic disorders of haemoglobin fall into two main groups:

1-The thalassaemias in which synthesis of the alpha or beta globin chain is reduced.

2-Structural disorders in which an abnormal haemoglobin is produced.

-The alpha or beta thalassaemias occur clinically as minor forms with microcytic hypochromic red cells and a raised red cell count with or without anaemia.total absece of function of all four alpha globin genes causes hydrops fetalis.

-Total absencce of function of both beta globin genes causes beta thalassaemia major , a transfusion –dependent anaemia associated with iron overload. Thalassaemia intermedia is a clinical term for a group of disorder showing mild to moderate anaemia and is usually caused by variants of beta thalassaemia.

-The most frequent structural defect of haemoglobin is the sickle mutation in the beta globin chain causing, in the homozygous form, a sever haemolytic anaemia, associated with vaso-occlusive crises.these may be painful affecting bone or affect soft tissue (e.g.chest,spleen or central nervous system).crises may also be haemolytic or aplastic.

-Antenatal diagnosis using PCR technology to amplify chorionic villous DNA is used to detect sever genetic defect of haemoglobin production,with termination of the pregnancy if appropriate .

  From book: Essentail Haematology A.V.HOFFBRAND,P.A.H.MOSS.6EDITION