FLP-Mapping

Summary

Genetic mapping with DNA sequence polymorphisms allows for map-based positional cloning of mutations at any required resolution. Numerous methods have been worked out to assay single nucleotide polymorphisms (SNPs), the most common type of molecular polymorphisms. However, SNP genotyping requires customized and often costly secondary assays on primary PCR products. Small insertions and deletions (InDels) are a class of polymorphisms that are ubiquitously dispersed in eukaryotic genomes and only about fourfold less frequent than SNPs. InDels can be directly and universally detected as fragment length polymorphisms (FLPs) of primary PCR fragments, thus eliminating the need for an expensive secondary genotyping protocol. Genetic mapping with FLPs is suited for both small-scale and automated high-throughput approaches. Two techniques best suited for either strategy and both offering very high to maximal fragment-size resolution are discussed: Analysis on nondenaturing Elchrom gels and on capillary sequencers. Here, we exemplify FLP-mapping for the model organisms Drosophila melanogaster and Caenorhabditis elegans. FLP-mapping can, however, be easily adapted for any other organism as the molecular biology involved is universal. Furthermore, we introduce FLP mapper, a JAVA-based software for graphical visualization of raw mapping data from spreadsheets. FLP mapper is publicly available at http://bio.mcsolutions.ch.