Immunodetection Array

A novel procedure for DNA methylation analysis is described that characterizes the extent of DNA methylation in CpG islands. The basic concept relies on direct immunodetection of 5′ methylcytosines (5′ mCs) without the need for bisulfite treatment utilizing a microarray format. This system is designed for the application of immunofluorescence using a monoclonal antibody that specifically recognizes 5′ mC in single-stranded DNA hybridized to oligonucleotide microarrays. An ultrasensitive fluorescence scanner and 170−μm thin aldehyde-functionalized glass slides are used to optimize the signal-to-noise ratio and to minimize autofluorescence. These methodological improvements allow for the direct detection of 5′ mC in genomic DNA hybridized to microarrays without prior PCR amplification with high analytical sensitivity.