Prenatal diagnosis of hemoglobinopathies in Ontario, Canada.

In 1989, the Province of Ontario established a molecular diagnostic laboratory for carrier detection and prenatal diagnosis of hemoglobinopathies. Over the past 15 years, the laboratory has provided prenatal diagnosis for 672 pregnancies at-risk for severe hemoglobinopathies: 276 (41%) for homozygous beta-thalassemia or hemoglobin (Hb) E/beta-thalassemia, 211 (31%) for homozygous alpha 0-thalassemia (Hb Bart's hydrops fetalis), and/or Hb H disease, and 185 (28%) for various sickling disorders (Hb SS, Hb SC, Hb S/beta-thalassemia). Despite the availability of services for carrier screening, genetic counseling, and prenatal diagnosis, there has been only a modest reduction in the overall incidence of hemoglobinopathies in Ontario.