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Letter to the editor
Editor, – The article 'Screening for thalassaemia' (Aust Prescr 2001;24:120-3) provided an excellent and concise overview of the thalassaemias and haemoglobinopathies in Australia.
A major point arises in relation to initial testing and how to identify a suspected carrier. While the thalassaemias and haemoglobinopathies are more prevalent in particular ethnic groups and geographical areas, the mutations causing these conditions can be found in virtually every country because of genetic drift and ethnic melding over the centuries.
Australia has a particularly heterogeneous population with an increasingly diverse pattern of these conditions. A positive family history is clearly an indication for testing, but this detects only a limited number of carriers. Clinical experience at our hospital shows that testing on the basis of name, place of birth or religion is unreliable for detecting carriers. Furthermore, reliance on red blood cell indices (MCH and MCV) as a screening process is inadequate. Haemoglobin electrophoresis is essential for the diagnosis of β thalassaemia minor and the haemoglobin variants of clinical significance, the latter being seen with increasing frequency due to recent immigration from Asia, Africa and the Middle East.
Comprehensive testing is advisable to provide optimal detection of couples at risk of having children with severe thalassaemia, so that they can be offered genetic counselling and prenatal diagnosis if appropriate. This means that, at the very least, all antenatal patients should be tested by full blood examination and haemoglobin electrophoresis (or HPLC), plus ferritin in the presence of microcytosis, as early in pregnancy as possible. Ideally, testing should occur in primary care before conception. Partner testing can then be pursued in accordance with the recommendations in the article.
F. Rex Betheras
Specialist in Charge
Royal Women's Hospital