CARRIER DETECTION AND PRENATAL-DIAGNOSIS OF HEMOGLOBINOPATHIES IN ONTARIO

The province of Ontario has a total population of approximately 10 mil lion people, with approximately 20% being of African, Southeast Asian, East Indian, Mediterranean, or Middle Eastern ancestry in whom the ge ne frequency for hemoglobinopathies is relatively high. In 1989, the O ntario Ministry of Health funded the establishment of the Provincial H emoglobinopathy DNA Diagnostic Laboratory located at the McMaster Univ ersity Medical Centre in Hamilton, Ontario. The Laboratory provides DN A analysis to identify the globin gene mutations in carriers and affec ted individuals, and performs prenatal diagnosis for severe hemoglobin opathies. Annually, more than 400 patient samples are referred to the Laboratory for investigation, of which 25-35 are fetal samples from pr egnancies at risk for either homozygous alpha-thalassemia, beta-thalas semia major, or sickling disorders. We have detected more than 70 diff erent globin gene mutations, including several mutations not previousl y reported in the literature. Here we present examples of the approach es used to detect globin gene mutations in a heterogeneous ''at risk'' population such as in Ontario, and discuss the impact of this service on patient care, genetic counselling, and the incidence of severe hem oglobinopathies in Ontario.