Population surveys were conducted on school children, adults and newborns. A total of 37,159 school children, age 8-17 years, both male and female, 1,629 adults, and 12,680 newborns were screened between 1966 and 1994. In addition, 4,564 patients with signs of hemolysis and/or low red blood cell (RBC) indices have been examined for the presence of thalassemias and/or abnormal Hbs. The methods for the detection and characterization of thalassemias and abnormal Hbs were those universally accepted [6,7], and consisted of the determination of RBC indices and morphology, osmotic fragility test [8], quanti tation of Hb A2 by column chromatography on DEAE-Sephadex [6] in the earlier studies, and microcolumn chromatography [9] in the later studies, quantitation of Hb F by an alkali denaturation procedure [6], and starch gel electrophoresis [10]. In addition, whenever indicated, specific studies such as tests for unstable Hbs, isoelectric focusing (IEF), structural characterization of variant Hbs, and in vitro biosynthesis studies [2,6,7], were performed. Gene mapping analysis, dot-blot hybridization of polymerase chain reaction (PCR), amplified DNA with specific probes, and sequencing of the amplified DNA followed methodology previously described [11-14].