Molecular pathology of the β-globin gene cluster

In the past few years there has been intensive study of the human globin genes. This study has provided important insights into normal gene structure and function and the nature of molecular defects leading to a set of inherited diseases. It is clear that a similar kind of analysis will soon be carried out on genes which cause single gene defects of neurological significance. Examples of disease-producing genes which are candidates for future analysis are those which produce Duchenne muscular dystrophy, Tay-Sachs disease and various other inherited degenerative diseases of the nervous system. When these genes are isolated one should expect to find common polymorphism or variation in the sequence of the normal gene and its surrounding DNA, and extensive heterogeneity in the mutations producing the defective genes responsible for the disorder. The major lesson derived from studies of β-globin genes is the expectation that genetic heterogeneity both in normal and disease-producing genes will be extensive. This heterogeneity will have important consequences for prenatal diagnosis and potential gene therapy.