title: Phenotypic and genotypic expression of alpha thalassaemia in Ibadan, Nigeria.
abstract: BACKGROUND
  Alpha thalassaemia is a common monogenic disorder found in most parts of the world but the severe form is restricted in its distribution while the mild deletional form of alpha- thalassaemia has a wider geographical distribution.
  
  
  METHODS
  One hundred and fifty one Nigerians which included 29 patients with unexplained recurrent haemolytic anaemia had their a-thalassaemia status determined by gap PCR after being screened using red cell indices.
  
  
  RESULTS
  Only the -alpha(3.7) deletion occurs among Nigerians with a gene frequency of 0.21. Forty-two per cent of the study population are heterozygotes, 9% are homozygotes while 49% are normal for this deletion. The mean haematocrit for the study population is 37.5%: homozygote, heterozygotes and normal subjects had a mean haematocrit of 37.3%, 37.5% and 37.7% respectively. The mean mean corpuscular haemoglobin (MCH) and haematocrit are significantly lower for patients than controls (24 +/- 2.9 pg vs. 26.6 +/- 2.5 pg (p = .000), 29% vs. 40% (p = .000) respectively). Forty three percent of both patients and controls had MCH of less than 27 pg but only 10% of patients had MCH that is greater than 27pg. Homozygote patients had a higher mean haematocrit than patients who are normal for the deletion (34.7% vs. 25.4%, p = 0.06) but homozygote patients had a lower mean haematocrit than homozygote controls (34.7% vs. 38.5%, p = 0.4).
  
  
  CONCLUSIONS
  This would suggest that alpha-thalassaemia is not responsible for the recurrent haemolytic anaemia observed in these patients and that the high prevalence of microcytosis among the normal populace needs further exploration.
authors: Department of Haematology, College of Medicine, University of Ibadan, Ibadan, Nigeria. tkotila@comui.edu.ng
authors: T R
authors: TR
authors: Kotila
mesh_terms: D004909:Erythrocyte Indices; D005260:Female; D005787:Gene Frequency; D005838:Genotype; D006400:Hematocrit; D006801:Humans; D008297:Male; D009549:Nigeria; D010641:Phenotype; D016133:Polymerase Chain Reaction / Q000379:methods; D012008:Recurrence; D017085:alpha-Thalassemia / Q000235:genetics*