The contribution of α+–thalassaemia to anaemia in a Nigerian population exposed to intense malaria transmission

Summary The proportion to which α‐thalassaemia contributes to anaemia in Africa is not well recognized. In an area of intense malaria transmission in South‐West Nigeria, haematological parameters of α‐thalassaemia were examined in 494 children and 119 adults. The –α3.7 type of α+‐thalassaemia was observed at a gene frequency of 0.27. Nine and 36.5% of individuals were homozygous and heterozygous, respectively. P.falciparum‐infection was present in 78% of children and in 39% of adults. The α‐globin genotypes did not correlate with the prevalence of P. falciparum‐infection. α+‐thalassaemic individuals had significantly lower mean values of haemoglobin, mean corpuscular volume, and mean corpuscular haemoglobin than non‐thalassaemic subjects. Anaemia was seen in 54.7% of children with a normal α‐globin genotype, in 69.9% of heterozygous (odds ratio: 1.99, 95% confidence interval: 1.32–3.00, P= 0.001), and in 88.4% of homozygous α+‐thalassaemic children (odds ratio: 7.72, 95% confidence interval: 2.85–20.90, P= 0.0001). The findings show that α+‐thalassaemia contributes essentially to mild anaemia, microcytosis, and hypochromia in Nigeria.