Received on January 20, 2006
Accepted on May 2, 2006

Molecular Diagnostics and Genetics

Matrix-Assisted Laser Desorption/Ionization Mass Spectrometric Analysis of DNA on Microarrays

¹ Max Planck Institute for Molecular Genetics, Department of Vertebrate Genomics, Ihnestrasse 63-73, 14195 Berlin-Dahlem, Germany

^* To whom correspondence should be addressed. E-mail: sauer{at}molgen.mpg.de.

Background: Matrix-assisted laser desorption/ionization (MALDI) mass spectrometry is a powerful tool in biomolecule analysis with a wide range of application possibilities, including genotyping of single-base variations (also known as single-nucleotide polymorphisms, or SNPs) for candidate gene studies and diagnostic typing of DNA markers. We tested a method that does not require stringent purification of the nucleic acids and/or the use of modification chemistry before mass spectrometry analysis.

Methods: We used an alternative direct analysis approach that allows MALDI analysis of crude DNA samples printed on microscope slides densely coated with primary amino groups that efficiently bind negatively charged DNA. After simple washing of the slides, we applied MALDI matrix and used a conventional MALDI mass spectrometer to detect DNA products.

Results: We analyzed crude oligonucleotide samples and performed automated genotyping of single-base variations in 72 DNA samples with a call rate of 95.8% and reliability of 99.98%.

Conclusion: This procedure offers an operational short-cut compared with standard MALDI procedures for preparation of oligonucleotides, including purification, and thus is an efficient tool for genotyping applications, particularly those requiring accurate, flexible, and rapid data generation and medium throughput.