Gamma chain variants in Jamaican newborns.

15,661 cord bloods from Jamaican infants were examined for abnormal hemoglobins using alkaline cellulose acetate electrophoresis for the initial screening, supplemented by acid agar gel electrophoresis for samples exhibiting abnormal hemoglobin bands. Of the 16 electrophoretic variants which were detected, six were fully characterized and found to be: four Hb F Port Royal (alpha2 Ggamma2 125 Glu replaced by Ala) and two Hb F Victoria Jubilee (alpha2Agamma2 80 Asp replaced by Tyr). The Hb F Port Royal samples each constituted about one eighth of the total Hb F as did seven additional samples presumed to be Hb F Port Royal. The infants with this variant exhibited no special hematological characteristics or other consistent associations. Both Hb F Victoria Jubilee samples occurred in somewhat lower proportions of the total Hb F compared with Hb F Port Royal and exhibited an apparent increase of free alpha chains in the whole hemolysate. The data available on detectable gamma chain variants suggest that a specific point mutation may occur in either a HbGgamma or a HbAgamma locus.