The moderating effect of haemoglobin A2 on morbidity in sickle cell anaemia patients

The presence of high blood levels of haemoglobin A2 (HbA2 ) has been noted in sickle cell anaemia (SCA) patients. This study was designed to determine if there is a relationship between high HbA2 levels and a reduction in the occurrence of vaso-occlusive crisis, complications and erythrocyte transfusion requirements in these patients. HbA2 levels were determined in 330 patients (mean age was 23.69±10.94 years) who presented consecutively to the Haematology clinics of the University of Benin Teaching Hospital, Edo State Central Hospital and Sickle Cell Center in Benin City, Nigeria. Of these, 200 (81.3%) were SCA patients in steady state and 46 (18.7%) having vaso-occlusive crisis, and 84 age and sex matched subjects served as controls. An automated Coulter Counter was used to determine blood count values while the haemoglobin A2 was estimated by HbS-free microcolumn chromatography. The mean HbA2 in steady state, vaso-occlusive crisis and control were 4.52% ±1.16, 3.82% ±1.27 and 2.13% ±0.98 respectively. HbA2 was significantly higher in steady state than during vaso-occlusive crisis (