A community profile of alpha thalassaemia in Western Australia

Objective: To investigate the current prevalence of α-thalassaemia in the population of Western Australia, which has received substantial immigration from South-East Asia during the last 30 years. Method: Over a 1-year period commencing July 2002, α-thalassaemia DNA testing was performed on 920 blood samples received from the Migrant Health Service, referring doctors or pathology laboratories in Western Australia. Molecular testing for α-thalassaemia was performed on extracted DNA for single and double α-globin gene deletions and mutations by PCR. Results: An α-globin gene abnormality was detected in 35.4% (326/920) of samples. There were 177 cases (50.6%) with a single gene deletion α⁺-thalassaemia, most commonly-3.7 kb, and 102 cases (31.2%) with double α-gene deletions (α⁰-thalassaemia), including 7 cases of HbH disease. Conclusion: Overall, the findings amount to 1.7 new cases of α-thalassaemia per 10,000 population in the 12-month period and demonstrate that α-thalassaemia is an increasingly common disorder in the Western Australian population. This has important implications for community outreach programmes, genetic counselling and the screening of at-risk populations.