CHROMOSOMES WITH ONE, 2, 3, AND 4 FETAL GLOBIN GENES - MOLECULAR AND HEMATOLOGIC ANALYSIS

  • 1 June 1986
    • journal article
    • research article
    • Vol. 67  (6) , 1611-1618
Abstract
Analysis of DNA from 852 Island Melanesians has revealed a high frequency of single- and triple-.gamma.-globin genes in this population. Homozygotes for triple- and single-.gamma. genes have normal hematologic findings, normal hemoglobin F (HbF) levels, and when there is coexisting .alpha. thalassemia, appropriate levels of Bart''s Hb (.gamma.4) at birth. In addition, we have identified an individual with a quadruple-.gamma. gene chromosome who also has a normal HbF level. All single-.gamma. genes were A.gamma., all triple-.gamma. genes G.gamma.G.gamma.A.gamma., and the quadruple-.gamma. gene G.gamma.G.gamma.G.gamma.A.gamma.. Analysis of G.gamma.:A.gamma. ratios in cord bloods and HbF levels in adults showed that these additional .gamma. genes are expressed and are down regulated appropriately by the fetal to adult Hb switch. Analysis of the restriction enzyme haplotypes of these various chromosomes indicates that intrachromosomal cross-overs are more likely to have produced these variants than interchromosomal recombination events.