SNP Genotyping by MALDI

Already in the late 1980s, with the introductions of matrix-assisted lasCT desorption/ionisation time-of-flight mass spectrometry (MALDI) and electrospiay ionisation mass spectrometry (ESI), it was recognised that the mass spectrometer might be an ideal tool for the analysis of DNA, proteins, and peptides. Initially, it 

Nevertheless, over the last ten years, mass spectrometric methods used for the analysis of DNA have come of age, so that now several procedures for the elucidation of DNA sequence variation are ready for integration into the postgenome sequencing era. Several of the protagonists of these developments have contributed chapters to this book. It was almost universally acknowledged that one of the major problems of DNA analysis by mass spectrometry was to achieve sufficient sample purity. Rather than to look for solutions for sample purification we decided to look for the reason for the sensitivity of DNA to impurities. 

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SNP genotyping by MALDI-TOF MS takes advantage of mass differences between allele-specific primer extension products. At present, three related assays are used, the PROBE— primer oligo base extension assay, which was further developed to the MassExtend assay by SEQUENOM— the PinPoint, and the GOOD assay (8). A representative scheme is depicted in Fig. 1. 

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