Relation of Xmn-1 Polymorphism & Five Common Indian Mutations of Thalassaemia with Phenotypic Presentation in b-Thalassaemia

ABSTRACT

Xmn-1 polymorphism is a known factor, which increases foetal haemoglobin production. Among, b thalassaemics in India five mutations are common. Disease severity was assessed based on age of presentation, age when received first transfusion and blood transfusion in ml/kg/year. Data was divided into three Xmn-1 categories, (+/+), (-/+), (-/-) and intergroup correlation was made. Mutations were divided into 2 groups, (group I) IVS 1-1 as one of its variables and (group II) without IVS 1-1. They were correlated. In Xmn-1 +/+ category 66.66% were diagnosed after one year of age, in mutations (group I) 53.57% had age of diagnosis after 1 year. 77.77% in Xmn-1 +/+ received their first blood transfusion after 1 year of age, in mutations (group I) 64.28% received their first blood transfusion after 1 year of age. About 66.66% patients in Xmn-1 +/+ category received blood <200ml/kg/year as against 72.22% in Xmn-1 -/- category. In mutations group I 57.14% received blood transfusion <200 ml/kg/year as against 68.18% in group II. It is concluded that the presence of Xmn-1 polymorphism and IVS 1-1 mutation leads to a milder phenotypic presentation causing a delay in onset of blood transfusions but dose not effect the amount of blood received /kg/year.