Mass array primer extension

DASH, dynamic allele-specific hybridization AS-PCR, allele-specific polymerase chain reaction AS-PE, allele-specific primer extension APEX, arrayed primer extension FP-TDI, fluorescence polarization template directed dye terminator incorporation MALDI-TOF-MS, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry OLA, oligonucleotide ligation assay RCA, ... 

Figure 10.3. Mass array, (a) Primer binding (b) primer extension enzyme, ddATP and dCTP/ dGTP/dTTP addition (c) primer terminates (d) primer extension products ready for MALDI-MS (e) MS spectrum of primer extension products. Each addition of a nucleotide to the primer extension product increases the mass by 289 to 329 Da, depending on the nucleotide added. The mass difference is easily resolved by MALDI-TOF, which has the ability to detect differences as small as 3 Da. Printed by kind permission of Sequenom. (See color insert.)...

Mass Array MALDI TOE MS Primer extension Mass spectrometry 49... 

Current methods combine at least one of four different principles of allelic discrimination (hybridization, primer extension, ligation, or restriction) with one of four different detection techniques (chemiluminescence/ fluorescence, fluorescence polarization, resonance energy transfer, and mass spectrometry). Assay formats range from (slab)- gel electrophoresis, plates, particles, fibre arrays, and microchip arrays to semi- and homogenous assays that do not require any further sample separation or purification. 

A different experimental approach to SNP detection combines mass spectrometric detection with enzymatic extension of primers hybridized to immobilized DNA target arrays. The advantage of this combination is high specificity and high accuracy of allele identification. 

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