In a cooperative intrastate program based upon experience with
sickle-cell anemia screening, the authors explored the feasibility of applying
hemoglobin electrophoresis for detection of
beta-thalassemia gene carriers. Initially, blood samples collected in capillary tubes were analyzed by
cellulose acetate electrophoresis with densitometric quantitation of
hemoglobin A2 (
Hb A2), followed by selective spectrophotometric quantitation. This approach proved insufficiently specific or reproducible. Follow-up hematologic and family studies of presumptive
beta-thalassemia gene carriers indicated that coordinate measurement of erythrocytic indices and
Hb A2 values would have discriminated a subpopulation with a high incidence of
beta-thalassemia trait more specifically. This approach was tested prospectively by the use of 731 venous blood samples collected in a county with a large population of Mediterranean ancestry. Of 31 individuals (4.2%) with presumptive
thalassemia trait, 13 returned for a repeat testing, and the initial results for 11 were confirmed. These findings lend support to an empirical screening sequence suggested by Pearson (erythrocytic indices followed by
Hb A2 quantitation), but they also indicate that a significant subpopulation of
beta-thalassemia gene carriers with limited phenotypic expression may elude detection in any single-pass approach.