Structure and organization of the human globin genes

A very precise picture of the fine structure and organization of the human globin genes has recently emerged from the study of cloned fragments of chromosomal DNA containing the globin genes and their flanking DNA. The precise sizes, locations and nucleotide sequences of intervening sequences (introns) that interrupt the globin genes have been determined. A number of presumably functionally important preserved nucleotide sequences common to all of the globin genes have been identified within the 5'-flanking DNA of the genes, as well as in their untranslated sequences and at the junctions between coding and intervening sequences. Intergene distances as well as the sizes of duplication units of closely related genes have been determined. A somewhat unexpected finding has been the identification of apparently nonexpressed globin pseudogenes within the globin gene clusters. Finally, detailed analysis of intergene DNA has revealed the presence of different types of repetitive DNA sequences in the vicinity of many of the globin genes but the significance of this finding with regard to the control of globin gene expression is not yet known.