The risk of alpha-thalassaemia in offspring of beta-thalassaemia carriers in Hong Kong

Prenat Diagn. 1997 Aug;17(8):733-6.

Abstract

Couples in whom one is heterozygous for alpha-thalassaemia-1 and the other is heterozygous for beta-thalassaemia are assumed not to be at risk of having offspring with homozygous alpha-thalassaemia-1 or homozygous beta-thalassaemia. We retrospectively reviewed the genetic outcome of 189 pregnancies of 178 couples in whom the partners were diagnosed to be discordant heterozygotes of alpha-thalassaemia and beta-thalassaemia on haematological tests. Zeta gene mapping was performed on 158 beta-thalassaemia carriers to diagnose the presence of co-existing alpha-thalassaemia-1. Eleven patients (7 per cent) were found to be compound alpha- and beta-thalassaemia heterozygotes. They accounted for 16 pregnancies, of which five were diagnosed to be affected by homozygous alpha-thalassaemia-1. Our results show that couples presumed to be discordant heterozygotes of alpha- and beta-thalassaemia on haematological testing are at risk of having offspring with homozygous alpha-thalassaemia-1 if the zeta gene mapping of the heterozygous beta-thalassaemia partner shows co-inheritance of alpha-thalassaemia-1. Prenatal diagnosis of homozygous alpha-thalassaemia-1 should be performed on these at-risk pregnancies.

MeSH terms

  • Chromosome Mapping
  • Erythrocyte Indices
  • Female
  • Hemoglobins / metabolism
  • Heterozygote*
  • Homozygote
  • Hong Kong
  • Humans
  • Pregnancy
  • Prenatal Diagnosis*
  • Retrospective Studies
  • Risk Factors
  • Ultrasonography, Prenatal
  • alpha-Thalassemia / diagnosis
  • alpha-Thalassemia / genetics*
  • beta-Thalassemia / genetics*

Substances

  • Hemoglobins