RELIABILITY OF ISOELECTROFOCUSING FOR THE DETECTION OF Hb S, Hb C, AND Hb D IN A PIONEERING POPULATION-BASED PROGRAM OF NEWBORN SCREENING IN BRAZIL

Abstract

Out of 128,326 newborns in the first 6-month period of a population-based screening program in Minas Gerais, Brazil, a second sample was obtained at the age of 6 months from 4,635 carriers of Hbs AS, AC, and AD which were detected by isoelectrofocusing. Discordance in results occurred in only 27 cases (0.6%): in seven there was a history of hemotransfusion; errors during pipetting or transcription of results occurred in seven cases; it was difficult to differenciate between Hbs S and D in eight patients; and the causes were not elucidated in five patients. The incidence of Hbs FS and FSC for the total population was 1 : 2,800 and 1 : 3,450, respectively. Isoelectrofocusing is a very reliable method for distinguishing AS, AC, or AD carriers from patients with presenting variant hemoglobin and β⁺-thalassemia combinations, and may be widely used in massive newborn screening programs.