Alpha Thalassaemia Gene Testing (BROCHURE)
(seven common deletions)
Test Information/Clinical Significance
Mutations of the alpha globin genes are among the most common known genetic defects. Their incidence in Australia is increasing. Testing in the Sonic Clinical Institute detects seven of the commonest alpha globin deletions. These are: _ _ SEA, _ _ FIL, _ _ THAI, _ _ MED, -alpha (20.5), -alpha 3.7, - alpha 4.2.
Alpha Thalassaemia genetic testing is useful for determining the cause of microcytic red cells in a patient with normal iron stores. Although a conventional thalassaemia screen will establish the diagnosis in a proportion of these patients, the test has a high false negative rate for alpha thalassaemia trait.
Molecular screening for the seven commonest alpha globin deletions is a useful second line test and will provide a definitive diagnosis in patients with one of these deletions. This is particularly useful in patients of childbearing age who may risk a more seriously affected child if their partner also has an abnormality of haemoglobin synthesis.
Note that a negative result does not exclude the presence of one of the rarer alpha thalassaemias or any form of non-alpha thalassaemia or haemoglobinopathy.
Method
The test is a PCR based investigation .
The test, will not, detect any beta globin defects, or any forms of alpha thalassaemia other than the above deletions.
Genetic Counselling
Genetic counselling is an essential aspect of testing for all genetic disorders and should be offered to patients prior to referral for testing and for discussion of test results.
Specimen
5 mL EDTA
Results Availability
Test performed weekly