Foetal haemoglobin levels in sickle cell anaemia in Nigerians

Abstract

Many patients with sickle cell anaemia (SCA) arc known to synthesize increased amounts of foetal haemoglobin (lib I7). In some situations, the levels attained are so high that the course of the disease is ameliorated since lib F does not participate in the polymerization process characteristic of the sickling phenomenon. It has also been reported that the simultaneous inheritance of an u-thalassacmia gene reduces the severity of SCA. We have examined the levels of lib F in relation to the erythrocyte indices and the coinheritance of the deletion type a-thalassacmin in SCA patients in Nigeria. The concentration of Mb F in peripheral blood was measured by the alkali denaturation technique of Betke et al. (15), whilst erythrocyte indices were determined on a Coulter S plus II counter. Alpha-thalassacmia was detected by the restriction endonuclease analysis of DNA obtained from peripheral white blood cells (WBC) and nucleated red cells using a-globin gene-specific probes. The mean lib F level in 130 SCA subjects was 5.9 ± 3.8% (range 0.9-16%). Males had significantly lower levels than females. lib concentration, haematocrit, and Hb A2 did not differ in subjects with Hb F levels lower than 2% (Group I) when compared with those whose I lb F levels were higher than 8% (Group II). The mean corpuscular volume (MCV) and mean corpuscular haemoglobin (MCI I) were lower in Group I. Globin analysis in 30 of these subjects showed that 20 had four, eight had three, and two had two a-globin genes. The mean lib F level (6.4 ± 3.7%) in the four alpha-gene group was significantly higher than that in the three alpha-gene group (2.7 ± "To whom correspondence should be addressed