Methylation

Infinium Methylation

Powered by Illumina’s revolutionary Infinium Assay, the HumanMethylation27 DNA Analysis BeadChip allows researchers to interrogate 27,578 highly informative CpG sites per sample at single-nucleotide resolution. 

The Infinium Methylation Assay detects cytosine methylation at CpG islands based on highly multiplexed genotyping of bisulfite-converted genomic DNA (gDNA). Upon treatment with bisulfite, unmethylated cytosine bases are converted to uracil, while methylated cytosine bases remain unchanged.

The assay interrogates these chemically differentiated loci using two site-specific probes, one designed for the methylated locus (M bead type) and another for the unmethylated locus (U bead type). Single-base extension of the probes incorporates a labeled ddNTP, which is subsequently stained with a fluorescence reagent. The level of methylation for the interrogated locus can be determined by calculating the ratio of the fluorescent signals from the methylated vs unmethylated sites.

 The 12-sample BeadChip features content derived from the well-annotated NCBI CCDS database (Genome Build 36) and is supplemented with more than 1,000 cancer-related genes described in published literature. Probe content has been enriched to deeply cover more than 150 well-established cancer genes known to show differential methylation patterns. HumanMethylation27 BeadChip content also targets the promoter regions of 110 miRNA genes.

Further information can be found here.