• alpha-thalassaemia;
  • ambiguous genitalia;
  • Hb H disease;
  • hydrops foetalis;
  • unstable haemoglobin

Haemoglobin H (Hb H) disease is caused by deletion or inactivation of three α-globin genes, leaving only one intact and active α-globin gene. People with Hb H disease usually have moderate anaemia, but are generally thought to be asymptomatic. Some Hb H disease patients require transfusions, and there are reports of fetuses with Hb H disease who have severe anaemia in utero resulting in fatal hydrops foetalis syndrome. We now report a case of Hb H hydrops foetalis syndrome, caused by the inheritance of a hitherto novel α-globin gene point mutation (codon 35 TCC[RIGHTWARDS ARROW]CCC or Serine[RIGHTWARDS ARROW]Proline) and an α-thalassaemia deletion of the Filipino type removing all ζ-α-globin genes on the other chromosome 16. The infant was delivered prematurely because of pericardial effusion and fetal distress, and was found to have severe anaemia and congenital anomalies. A review of the relevant literature on this syndrome is presented, and serves to underscore the phenotypic variations of Hb H disease and the need for surveillance for this condition among newborns and genetic counselling in communities with a high proportion of at-risk populations.