Journal of Blood Disorders & Transfusion

Abstract

The Diagnosis of Beta Thalassemia with Borderline HbA2 Level among Kelantan Population

Rosnah B, Nani Shahida S, Mohd Nazri H, Marini R, Noor Haslina MN, Shafini MY, Wan Zaidah A

Level of HbA2 more than 4% is the reliable parameter to identify β- thalassemia carrier. However, in some cases the level is not typically increased hence leading to diagnostic dilemma. Thus the objectives of this study were to evaluate the existence of β- thalassemia among borderline HbA2 sample. Out of 11,790 samples received for thalassemia screening, 405 (3.4%) were found to have borderline HbA2 level. Out of this, 117(28.9%) samples were selected by simple random sampling for PCR. Multiplex ARMS-PCR was used to detect β-globin gene mutation and multiplex gap PCR for α-globin genes deletion. The result revealed 36 (30.8%) had β-globin gene mutations, 8 (6.8%) had α-globin gene deletions and 1 (0.9%) had coexistence of α and β-globin gene defects.

The commonest gene mutation detected were CD 19 (A-G), detected from 17 (45.9%) samples, followed by 9 (24.3%) with IVS 1-1 (G-A) mutation, 5 (13.5%) with Poly A mutation and 1 (2.7%) showed CAP +1 (A-C) mutation. Two samples (5.4%) showed mutations of Poly A and CD19, 2 (5.4%) showed mutation of IVS 1-1 and CD 19 while 1 (2.7%) showed IVS 1-5 and CD 19 mutations. This study showed 10 (27.0%) positive molecular results even though the HbA2 level was at only 3.0%. There was significant number of people with HbA2 between 3.0% and 3.9% and confirmed as thalassemia carriers by PCR. This data may suggest the level of HbA2 need to be revised to ensure the success of thalassemia screening programme in our population.