Heterocellular hereditary persistence of fetal haemoglobin affects the haematological parameters of beta-thalassaemia

Chad Garner1, Tracy K Dew, Roy Sherwood

  • 1Department of Environmental Analysis and Design, Division of Epidemiology, University of California, Irvine, CA, USA.

To assess and define the effects of heterocellular hereditary persistence of fetal haemoglobin (HPFH) on the haematological phenotype of heterozygous beta-thalassaemia, we have studied a large kindred that included a total of 204 subjects with 60 beta-thalassaemia carriers, of whom 35 were also heterozygous, and five homozygous, for heterocellular HPFH. The study was possible because of the homogeneity of the beta-thalassaemia mutation and the ability to genotype the heterocellular HPFH allele. Heterocellular HPFH had a significant effect on the mean corpuscular haemoglobin (MCH), mean corpuscular volume (MCV) and haemoglobin (Hb) A2 values in the beta-thalassaemia carriers and accounted for 29%, 30% and 24% of their respective variances. beta-thalassaemia subjects with heterocellular HPFH had higher MCV and MCH values, concomitant with lower levels of Hb A2, and a reduced ineffective erythropoiesis. We conclude that co-inheritance of heterocellular HPFH leads to a primary increase in gamma-chain synthesis in beta-thalassaemia trait and can be another confounding factor in the use of red cell indices and Hb A2 levels in population screening for beta-thalassaemia.

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