Mutation Analysis and confirmation of beta thalassemia in Nepalese population

Abstract

Beta (β) thalassemia is genetic disorder which passes from parents to their offspring in an autosomal recessive inheritance pattern. This disease is directly related to the haemoglobin chemical anatomy and functioning. This genetic disease leads to defective beta globin haemoglobin chain which means partial or complete loss of beta globin chain synthesis. This chemistry in RBCs make them vulnerable to lysis of cells themselves prematurely resulting in anaemia. Beta-thalassemia hence requires continuous blood transfusion along with other care to maintain the normal homeostasis of RBCs and other systems of body. This management procedure is costly, sensitive and tedious and became serious health problem in developing nation like Nepal. 107 subjects were selected of which 61 were already clinically distinguished cases and remaining were one of their immediate family members as carrier unaffected according to clinical data. These two groups were carefully recruited and evaluated by means of multiplex ARMS PCR. The multiplex ARMS PCR results were validated by direct sequencing. The group of 21 major mutations were investigated using allelespecific primerscategorised in 6 different panels in this study but only 9 mutations were revealed during study. Unaffected family member were analysed to find the link among them. The most common mutations were found as IVS 1-5(G-C) and Cd 26(G-A) with 23% followed by 619 deletion (20%), Cd 8/9(+G) 12%, Cd 16 (-C) 8%, Cd 41/42(-TTCT) 6%, IVS 1-1 (G-T) 4%, Cd 19 (A-G) 3% and Cd 17(A-T) 1% respectively. Heterozygous and homozygous mutation types were analysed using internal controls. The result of this study reveals that the mutational profile of Nepal resembles with two neighbouring countries China, India and other South Asian countries. Previously it was assumed that thalassemia is common in Terai region only but our study reflects its distribution all over Nepal in most of the ethnic groups. This technique has proved its value in β thalassemia studies and has been used widely for the analysis of β thalassemia worldwide. It is found reliable, simple, quicker and affordable. It is recommended to participate in the thalassemia screening programmes before marriage in endemic areas. And for the married couples to take prenatal diagnosis of foetus in high risk populations to predict and prevent or stop the frequency of the new patients in early future.

Keywords: (β) thalassemia, autosomal recessive, Multiplex ARMS PCR, Sequencing, high risk population, prenatal diagnosis, Nepalese population.