No abstract

We have derived a 'map' of restriction enzyme sites in and around the human gamma-globin genes. This has enabled us to show that there are two gamma-globin genes per haploid set, that the genes contain 'introns' within the same regions of DNA as the human beta and delta-globin genes, and that the genes are 3,500 base pairs apart. We conclude that the correct gene organisation of the human beta-like globin locus is GgammaAgammadeltabeta.

Twenty-one cases of beta 0 and beta +-thalassaemia have been analysed by restriction endonuclease mapping. In most cases no deletion in the regions surrounding the beta- and delta-globin genes could be detected. However, in a single Asian case of beta 0-thalassaemia, homozygous clinically, one of the homologous chromosomes contained a beta-globin gene with a deletion of 600 base pairs of DNA and comprising most or all of the 3' end of the structural gene including the EcoRI restriction site within the beta-globin coding sequence.

No abstract

Many human globin-chain mutants contain amino acid replacements that result from single base changes in the corresponding globin gene. Using recombinants, the coding sequences of each of the alpha-, beta-, Ggamma- , and Agamma-globin genes have now been determined. Those sequences of DNA that are cleaved by a number of specific restriction endonucleases have been identified and accurately positioned. Mutations at these sequences abolish the restriction site, and therefore, the pattern of DNA fragments containing hybridizing globin-gene sequences is altered compared to DNA from normal persons. This allows the identification of one of a pair of cross-hybridizing human globin-gene sequences, as is shown here for the two alpha-globin, the two gamma-globin, and the delta- and beta-globin genes.