Schematic diagram of in-gel competitive reassociation (IGCR) procedure. Closed bars, target-specific DNA fragments; open bars, common DNA fragments derived from target DNA; shaded bars, common DNA fragments derived from reference DNA; short open bars, adaptors for PCR amplification. BAP, bacterial alkaline phosphatase. Circles at the end of the bars represent phosphate moieties. Target-specific restriction fragment length polymorphism products, which are enriched after IGCR, are shown at the bottom of the chart (closed bars with adapters).