Globin genes: a paradigm of gene structure, function, and evolution.

Access to the detailed structure of the globin (and other) genes has taught us at least three valuable, but not necessarily expected, lessons regarding the structure and evolution of the genes. Foremost, at least in terms of its surprising nature, is the fact that many genes are interrupted, i.e., they contain discontinuous blocks of coding and noncoding information. No less surprising are the accompanying facts that chromosomal DNA changes by the movement and rearrangement of large pieces of DNA and that genetic loci are highly and unexpectedly complex, consisting of arrays of related genes and pseudo (or apparently nonfunctional) genes. Here we review some of the evidence upon which these conclusions rest, and we try to form a coherent picture of gene evolution. The evidence that we shall use is based on studies of the mouse globin. Evidence from various other genetic systems leads us to believe that these genes serve as an instructive general model rather than an idiosyncratic one.