Characterization of New Alpha Zero (α 0 ) Thalassaemia Deletion (-- GB ) among Malays in Malaysian Population.

Malaysia is a multicultural and multiethnic country comprising numerous ethnic groups. From the total population of 32.7 million, Malays form the bulk of the Bumiputera in Malaysia comprise about 69.9%, followed by Chinese 22.8%, Indian 6.6%, and others 0.7%. The heterogeneous population and increasing numbers of non-citizens in this country affects the heterogeneity of genetic diseases, diversity, and heterogeneity of thalassaemia mutations. Alpha (α)-thalassaemia is an inherited haemoglobin disorder characterized by hypochromic microcytic anaemia caused by a quantitative reduction in the α-globin chain. A majority of the α-thalassaemia are caused by deletions in the α-globin gene cluster. Among Malays, the most common deletional alpha thalassaemia is -α 3.7 deletion followed by -- SEA deletion. We described the molecular characterization of a new -- GB deletion in our population, involving both alpha genes in cis . Interestingly, we found that this mutation is unique among Malay ethnicities. It is important to diagnose this deletion because of the 25% risk of Hb Bart's with hydrops fetalis in the offspring when in combination with another α 0 - thalassaemia allele. MLPA is a suitable method to detect unknown and uncommon deletions and to characterize those cases which remain unresolved after a standard diagnostic approach.