The contribution of alpha(+)-thalassaemia to anaemia in a Nigerian population exposed to intense malaria transmission

The proportion to which cr-thalassaemia contributes to anaemia in Africa is ,not well recognized. In an area of intense malaria transmission in South-W est Nigeria, haematological parameters of a-thalassaemia were examined in 4 94 children and 119 adults; The -alpha(3,7) type of alpha(+)-thalassaemia w as observed at a gene frequency of 0.27. Nine and 36.5% of individuals were homozygous:and heterozygous, respectively P. falciparum-infection was pres ent in 78% of children and in 39% of adults. The alpha-globin genotypes did not correlate with the prevalence of P. falciparum-infection. alpha(+)-tha lassaemic individuals had significantly lower mean values of haemoglobin, m ean corpuscular volume, and mean corpuscular haemoglobin than non-thalassae mic subjects. Anaemia was seen in 54.7% of children with a normal alpha-glo bin genotype, in 69.9% of heterozygous (odds ratio: 1.99, 95% confidence in terval:1.32-3.00, P = 0.001), and in 88.4% of homozygous alpha(+)-thalassae mic children (odds ratio: 7.72, 95% confidence interval: 2.85-20.90, P = 0. 0001). The findings show that alpha(+)-thalassaemia contributes essentially to mild anaemia, microcytosis, and hypochromia in Nigeria.