Haemoglobin F Victoria Jubilee (alpha 2 A gamma 2 80 Asp-Try)

Haemoglobin gene frequencies in the Jamaican population: a study in 100,000 newborns

The gene frequencies of abnormal haemoglobins have been determined in a group of 100,000 Jamaican newborns screened over a period of 8 1/2 years. The population is predominantly of West African origin and the survey represents approximately one quarter of all island deliveries within the period of the study. The common beta globin chain abnormalities beta s and beta c occurred with gene frequencies of 0.055 and 0.019 respectively; beta thalassaemia was relatively rare. In contrast, alpha thalassaemia was quite common, occurring with a gene frequency of 0.183. In addition to these common abnormalities, the frequencies of 256 rare abnormal haemoglobins are described. This survey thus represents a complete and accurate documentation of the alpha and beta globin variants that occur in the Jamaican population.

Survey of cord blood hemoglobin in Japan and identification of two new gamma chain variants

Two gamma chain variants were discovered during a survey of 2,569 cord bloods of Japanese. One was the first case with mutation of the T-gamma chain, i. e. Hb F Yamaguchi or gamma 80 (EF 4) Asp leads to Asn (75 Thr, 136 Ala). It comprised 33.6% of Hb F, an unusually high percentage for a gamma chain variant. The other concerned with the first report of substitution at E 16, i. e. Hb F Iwata or gamma 72 (E 16) Gly leads to Arg (75 Ile, 136 Ala). It comprised 11.0% which is comparable to the values usually reported in an A-gamma chain variant. No clinical consequences have been observed in association with the hemoglobin variants.

gamma chain composition in five Italian newborns heterozygous for Hb F Malta G gamma-117 His leads to Arg

The percentage of Hb F Malta G gamma-177 His replaced by Arg and the gamma chain composition have been evaluated at birth and at different times after birth in five Italian newborns heterozygous for this variant. The percentage of Hb F Malta ranged at birth from 24% to 31% of the total Hb F, while the average G gamma/A gamma chain ratio was about 7/3, overlapping the values observed in normal newborns. T gamma chains were detected in three out of five newborns, with a percentage of about 10% of the total Hb F. After birth the Hb F Malta declined faster than the total Hb F; thus, the Hb F decrease during the first 45 d of life is mainly due to the switch-off of the G gamma locus containing the Hb F Malta gene.

The human gamma-chain variants. A review

The human gamma-chain variants are discussed in relation to their chemical structures and to the importance that their study has had for our present knowledge of the genetics and biosynthesis of hemoglobin chains.

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.