ABSTRACT
As a first step toward obtaining a complete description of the human genome, detailed physical and genetic linkage maps of all the human chromosomes must be established. Since the idea was first proposed in 1980 that a genetic linkage map of the human genome could be made using DNA probes that detect restriction fragment length polymorphisms, an extraordinary amount of progress has been made in developing DNA markers and using them to map human chromosomes. Today, preliminary genetic linkage maps exist for all the human chromosomes. The earliest type of genetic marker used in human genetics was the protein polymorphism. This was a polymorphism of the gene product and was defined by various marker systems that included serological tests for blood group antigens and tests to detect electrophoretic variants of different proteins and enzymes.
