Predictors of thalassaemia carriers in Trinidad and Tobago

ABSTRACT

OBJECTIVE: To determine possible predictors of thalassaemia carriers among prospective blood donors in Trinidad and Tobago. DESIGN AND METHODS: 460 prospective blood donors were screened for microcytosis (MCV<83fL) by performing a complete blood count (CBC) using a Sysmex XE-2100. The 86 samples with microcytosis further had a blood film analysis, iron studies, haemoglobin electrophoresis, haemoglonin F and A2 quantification, and DNA analysis for thalassaemia mutations. Statistical analysis was done using SPSS to determine predictors of thalassaemia trait. The variables tested were ethnicity, haemoglobin, mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), mean corpuscular hemoglobin volume (MCHC), red blood cell (RBC), RBC distribution width (RDW-SD and RDW-CV). We looked at different mathematical formulae to predict thalassaemia trait ie the Mentzer Index, Shine and Lal Index, Green and King Index, Srivastava Index, RDW Index and the red cell indices tested were RDW-CV, RDW-SD and RCC. RESULTS: 86 (18.7%) subjects had microcytosis. 44(51.2%) of these had DNA results. 31(70.5%) had thalassaemia trait 25(80.6%) with genotype –α/αα, 4(12.9%) α-/α-(all α3.7), one IVS I-5 G/C and one IVSII-666 T/C. The MCV, RDW-SD and RDW-CV were useful in predicting thalassaemia trait. RDW-SD identified 30 (96.8%) of the 31 carriers, the Green and King formula identified 27 (87.1%), and Ricerca index identified all 31 (100%). CONCLUSION: MCV, RDW-SD, Green and King formula and Ricerca index may be useful predictors of thalassaemia trait in Trinidad and Tobago.