AB023. Problem in the prevention and control of thalassaemia in Asia

Abstract: Thalassaemia is the most common inherited single gene condition in the world. It is especially highly prevalent in the Asian Pacific region and poses a major public health problem. Carrier frequencies of the 2 major types of thalassaemia, the α and the β-thalassaemia, range from 3-40%, and vary from one country to another and within the same country in different ethnic groups. The most severe form of α-thalassaemia is Bart’s hydrops fetalis. This is a lethal condition that also poses an increased risk for maternal morbidity. Children with β-thalassaemia major are born healthy but require life-long transfusion with expensive iron chelation therapy, or bone marrow transplant to survive. Control of thalassaemia is further complicated by the prevalence of HbE in this region. Individuals who co-inherit HbE and β-thalassaemia have thalassaemia intermedia with severity range from mild to severe anaemia requiring transfusion. The key to control thalassaemia is to identify the population at risk and to offer genetic counselling and providing options to prevent the disease in the family. Routine full blood count and Hb electrophoresis can reliably identify most if not all β-thalassaemia and HbE carriers, and majority of α-thalassaemia carriers. Detection of mutation causing thalassaemia enables accurate identification of carrier at risk and allows early prenatal diagnosis to be carried out. This is especially important in identifying at risk individuals who are both α and β-thalassaemia carriers. However, molecular diagnosis is expensive and effective screening requires prior knowledge of the spectrum of mutations in the population. Planning of an effective screening strategy depends on available resources and prevalence of the disease. In many countries, screening is carried out at pregnancy when option for prevention is possible. While screening and prevention may be effective to reduce number of major type of thalassaemia, more resources for optimal treatment can then be made available to those who are seriously affected by the disease.

Keywords: Thalassaemia carrier; anaemia; screening; mutation; counselling