Screening techniques for detecting allelic variation in DNA sequences

This article reviews four 'DNA screening techniques', namely heteroduplex analysis, single-strand conformational polymorphism (SSCP), denaturing gradient gel electrophoresis (DGGE) and temperature gradient gel electrophoresis (TGGE) as tools for the study of allelic variation in natural populations. The resolving power, advantages, and limitations of each technique are discussed and compared. We also provide some criteria for choosing among techniques and illustrate some practical issues with examples taken primarily from our own laboratory experience.