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

Abstract

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 (P<0.01). Erythrocyte transfusion requirement and occurrence of complications were significantly lower with higher HbA₂ value (P=0.042 and P=0.038 respectively). High HbA₂ levels are associated with lower morbidity in sickle cell anaemia patients. Treatment strategies, which increase HbA₂ , may be beneficial in managing SCA.

Keywords: Haemoglobin A₂ ; sickle cell anaemia; morbidity.

International Journal of Biological and Chemical Sciences Vol. 1 (3) 2007: pp. 287-292