Micro mapping of common alpha thalassaemia deletions (3.7 kb, 4.2 kb) in Sri Lanka and assessment of the contribution of alpha thalassemia to hypochromic microcytosis

Abstract

INTRODUCTION AND OBJECTIVES: The exact prevalence and distribution of a thalassaemia in Sri-Lanka is not known, and it is widely believed that single gene deletion of a thalassaemia does not cause hypochromic rnicrocytic anaemia. To micro map the distribution of the common athalassaemia deletions in Sri Lanka and to assess its contribution to hypochromic microcytosis in the community. METHODS: A national survey on haemoglobin disorders was carried out between 2009-2010 covering all 25 districts where 300 school children of each district were screened for haemoglobin disorders and anaemia. As part of the survey 3.7 kb and 4.2 kb common alpha plus deletions were analysed using polymerase chain reaction (PCR) Gap PCR in two groups. Group 01,,2038 subjects with hypochromTc rnicrocytic anaemia [MCV < 80 fl; MCH < 27 pg], Group 02, 1305 subjects with normal MCV and MCH. RESULTS: Overall prevalence of a thalassaemia in Sri-Lanka was 9.49 % of which 3.7kb was the commonest deletion (8.27%) whilst the 4.2kb deletion accounted for 1.14%. The distribution of a thalassaemia showed remarkable variabiiity within the districts in Sri Lanka ranging from (16.33%) in Kurunegala to (3.86%) in Galie. Contrary to the present belief a thalassaemia due to single gene deletions is most often associated with hypochromic microcytic anaemia (95%) than not (5%).