A community profile of a-thalassaemia in Western Australia

Abstract

Over the last 50 years there has been substantial migration to Australia. Initially migrants came from Europe, but over the last 30 years significant numbers have originated in SouthEast Asia and more recently SubSaharan Africa. Because of the changed migration pattern it is believed that a-thalassaemia mutations have been introduced. This paper reports the results of a one-year study of the prevalence of a-thalassaemia in Western Australia. Testing for a-thalassaemia was performed on 920 blood samples referred from doctors or pathology laboratories in Western Australia as part of the investigation for a haemoglobinopathy. Molecular testing was performed on extracted DNA for single and double a-globin gene deletions and mutations by PCR. An a-globin gene abnormality was detected in 35.4% (326/920) of samples. There were 177 cases (50.6%) with a single gene deletion a+-thalassaemia, most commonly -a3.7kb, and 102 cases (31.2%) with double a-gene deletions (a0- thalassaemia), most commonly --SEA, including 7 cases of HbH disease compound heterozygotes, were also detected. These findings amount to 1.7 new cases of a-thalassaemia per 10,000 population in the 12-month period and demonstrate that a-thalassaemia is an increasingly common disorder in the Western Australian population. This has implications for genetic counselling and health screening of at-risk populations