A novel method to quantitate methylation of specific genomic regions.

A new solid-phase primer extension method has been developed for the quantitation of methylation differences and is described here. The method is less cumbersome than Southern blot analysis, expresses the results in a numerical format, can be adapted to a microtitration well format, and thus allows the analysis of a large series of samples. The model gene analyzed here is the calcitonin gene, but the method can be adapted to the analysis of methylation alterations in any area of the genome. The primer extension method clearly differentiated hypermethylated samples from normally methylated samples and a range for normal values could be determined. In quantitation experiments the method showed linearity in a range from 2% to 100% malignant blasts diluted with normal leukocytes.