DNA testing of couples who are both carriers is necessary for prenatal diagnosis to be available. Testing can be time-consuming and, if possible, couples should be tested and referred prior to pregnancy.
This is usually performed in the first trimester but, under certain circumstances, may be performed in the second trimester. Some combinations of thalassaemia and haemoglobin variants can result in a clinically affected child. It usually represents 2 to 3. Each individual has two copies of this gene, one from each parent. This is a severe medical condition requiring frequent blood transfusions and iron chelation therapy. While this is not a serious medical condition, it manifests as reduced red cell indices and elevated concentrations of HbA2, and can be mistaken for iron deficiency.
This risk applies for every pregnancy of that partnership. This is known as compound heterozygosity, as the two types of gene mutations are different. Nucleated red blood cells are usually present. Affected children over the age of six months usually have markedly elevated levels of HbF and elevated HbA2. Contact a haematologist for advice. These patients require the same immunisation as other children and prompt treatment of infections.
It causes life-long anaemia of mild to moderate degree. In addition, the mother of an affected fetus is at risk of severe early pre-eclampsia, ante-partum or post- partum haemorrhage, and pre-term delivery. HbH disease can cause life-long anaemia of mild to moderate degree and sometimes requires transfusion support. Medical management is advised. This is not clinically significant; however, haemoglobin is often in the low end of the normal range and MCV and MCH may be reduced.
In younger individuals HbH preparation demonstrates presence of varying amounts of HbH. Testing the partner is an urgent priority if the woman is already pregnant. This results in red blood cells that form an irreversible sickle shape after repeated cycles of deoxygenation.
Carriers are usually healthy. In some very rare instances eg anaesthesia or long distance air travel , the red blood cells of a carrier can undergo partial sickling. However, with increasing immigration from sub Saharan Africa and the Indian subcontinent , HbS is becoming more prevalent. Where the sickle cell carrier state is identified it is essential that the partner be investigated. In some very rare instances, eg anaesthesia , the red blood cells of a carrier can undergo sickling.
Anaesthetists should be informed when a patient is a carrier for sickle cell disease. Table 2. Haemoglobinopathies: how much should the GP know? Modern Medicine of Australia, March, — Prevention of Thalassaemias and other Haemoglobin Disorders. Vol 1, Nicosia, Thalassaemia International Federation. The Thalassaemia Syndromes. Bibliography Angastiniotis M and Modell B, Global Epidemiology of Hemoglobin Disorders.
Annals of the New York Academy of Sciences, Barlow-Stewart K, Screening for thalassaemia. Australian Prescriber, Thalassaemia disorders. Tony Abbott, Australian Minister for Health and Ageing, said: 'Genetic medicine is a constantly evolving field and this handbook Having been informed by extensive consultations with GPs, consumers and genetics healthcare professionals and peer-reviewed by an expert advisory group, Australian officials envisage that the handbook will become the 'gold standard' for genetics information for GPs and other health professionals.
Abbott believes the handbook, heralded as 'the only one of its kind available' by Ian Macfarlane, Australian Minister for Industry Tourism and Resources, is a significant step towards improving the patient journey for the many people affected by genetic conditions.
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