Hereditary persistence of foetal haemoglobin with β-chain synthesis in cis position (^Gγ-β⁺-HPFH) in a negro family

Abstract

HEREDITARY persistence of foetal haemoglobin (HPFH) is an uncommon condition described mainly in negroes and Greeks. Although this genetic disorder is rare, it has been very important in the study of the arrangement of human globin genes on chromosomes and in the investigation of the regulation of foetal haemoglobin synthesis. It is not always possible to distinguish clearly between HPFH and thalassaemia and there is considerable genetic heterogeneity in these conditions. A majority of patients with HPFH have an increased amount of foetal haemoglobin, normal or near normal red cell indices, Hb F in each red cell, an absence of clinical manifestations in the simple heterozygous state or in combination with Hb S, Hb C, or Hb E, and balanced globin synthesis¹. Two different forms of γ chains are normally synthesised, with either glycine or alanine at the γ¹³⁶ position. Although the majority of negro heterozygotes for HPFH have both glycine and alanine at γ¹³⁶, several patients have had only glycine^2–5. There was no synthesis of β or δ chains in the cis position to the HPFH gene in any of the appropriate negro cases reported previously. We describe here a negro family in which the proposita had Hb S-HPFH with β-chain synthesis in the cis position to the HPFH gene.