Hemoglobin H (Hb H) disease in Canada: molecular diagnosis and review of 116 cases

Am J Hematol. 2001 Sep;68(1):11-5. doi: 10.1002/ajh.1142.


Over the past decade, we have characterized at the DNA level a total of 116 hemoglobin H (Hb H) disease patients living in Canada. The majority of patients were of southeast Asian descent (Chinese, Filipino, Laotian, Vietnamese), with a small number being of Mediterranean, Middle Eastern or East Indian background. A total of 15 distinct genotypes were detected, all but one being compound heterozygotes for a two-gene cis deletion and a single-gene deletion (-alpha/-) or a non-deletion mutation of the alpha2-globin gene (alpha(T) alpha/-). Seven different two-gene cis deletions were encountered, along with nine single-gene deletions and point mutations. The wide range of mutations associated with Hb H disease in Canada is a reflection of the population heterogeneity. The diagnosis of Hb H disease at the molecular level is important with respect to genetic counseling and the identification of families at risk for having pregnancies affected with Hb Bart's hydrops fetalis syndrome and/or Hb H disease. Six of the Hb H disease patients in our cohort had spouses who carried single-gene deletions, making these couples at risk for having children with Hb H disease. More important, seven patients had partners who carried two-gene cis deletions. These couples are at reproductive risk for both Hb Bart's hydrops fetalis syndrome and Hb H disease.

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Alpha-Globulins / genetics*
  • Canada
  • Child
  • Child, Preschool
  • DNA Mutational Analysis
  • Female
  • Gene Deletion
  • Genotype
  • Heterozygote
  • Humans
  • Infant
  • Male
  • Middle Aged
  • Retrospective Studies
  • alpha-Thalassemia / diagnosis*
  • alpha-Thalassemia / genetics*


  • Alpha-Globulins