Molecular diagnosis of Beckwith-Wiedemann Syndrome using quantitative methylation-sensitive polymerase chain reaction

Purpose: Beckwith-Wiedemann Syndrome is caused by defects in imprinted gene expression at 11p15. Currently, quantitative Southern analysis using DNA methylation-sensitive restriction enzymes is used in molecular diagnosis of this syndrome. Methods: We describe a rapid and highly quantitative test for assessing DNA methylation at 11p15 using sodium bisulfite treatment of genomic DNA coupled with quantitative TaqMan methylation-sensitive polymerase chain reaction. Results: TaqMan MSP can assess DNA methylation at both differentially methylated region (DMR)1 and DMR2 at 11p15. In addition, by using TaqMan MSP we were able to determine the parent of origin of a duplication of 11p15 by quantification of both DMR1 and DMR2 DNA methylation. Conclusion: TaqMan MSP method is a robust and rapid method for detecting changes in DNA methylation that compares favorably to the current standard of Southern blot for DNA methylation analysis. Assessment of DMR1 and DMR2 provides the most comprehensive assay for methylation defects in Beckwith Wiedemann Syndrome, accounting for more than 70% of the cases. The advantages of TaqMan IVISP are that it requires less DNA and that it is rapid, less labor-intensive, and amenable to high-throughput analysis. Moreover, this approach can be modified to assess DNA methylation changes anywhere in the genome.