Two-dimensional DNA typing: A cost-effective way of analyzing complex mixtures of DNA fragments for sequence variations.

By two-dimensional (2D) DNA typing, multiple DNA fragments can be analyzed in parallel for all possible sequence variations. The method involves electrophoretic separation in polyacrylamide gels, first by size and subsequently on the basis of basepair sequence in a denaturing gradient. The system has been automated partly and a dedicated image analysis system for rapid interpretation of the often complex spot patterns was developed. In this review, the basic principles of 2D DNA typing, its methodology, and some major applications in genetic studies of animals, plants, and microorganisms will be discussed, with the emphasis on human genetics.