Heteroduplex analysis

This representation of heteroduplex analysis shows how this technique can be used to distinguish between an individual with normal DNA and heterozygous for a gene mutation. An individual's DNA is amplified by polymerase chain reaction (PCR), and the PCR products from both alleles are mixed and denatured (top section). The PCR products are then reannealed, allowing all combinations of DNA pairing. Homoduplexes are generated by the pairing of normal with normal and mutant with mutant DNA; heteroduplexes are generated from the pairing of of normal with mutant DNA. (middle section). The mutation is denoted by an "X".
Lane 2: DNA from an individual homozygous for the normal gene forms only homoduplexes, which run faster through the gel.
Lane 3: DNA from an individual heterozygous for the gene mutation forms heteroduplexes, which contain bubbles. This makes the DNA run more slowly through the gel.