Strategies for detecting genomic DNA methylation: a survey of US patents

DNA methylation is one of the mechanisms for the epigenetic control of gene expression. Alterations in the methylation status of genomic DNA can result in the silencing of genes. Such control is of significance for a wide range of biological processes, ranging from cellular differentiation during development, genomic imprinting and X-chromosome inactivation to the maintenance of genome stability. The cytosine in the genomic DNA is converted to 5-methylcytosine. The hypermethylation of some CpG islands in genomic DNA could result in gene silencing and hypomethylation can lead to transcription and gene expression. There has been a great interest in developing molecular techniques to analyze genomic DNA methylation at the CpG islands. The discovery that DNA treatment with sodium bisulfite converts the cytosine to uracil while keeping the 5-methycytosine intact has opened the door to a number of strategies to investigate genomic DNA methylation both at regional and global levels. A survey of recently patented methods to analyze DNA methylation indicated a range of inventions from simple PCR to high throughput based technologies. The disease diagnosis was the prominent application of DNA methylation detection for most of these methods. Future inventions will likely concentrate on genome-scale DNA methylation discovery.