Methylation of the rDNA promoter in MDS CD34⁺ cells using pyrosequencing. Heat map representation of the extent of rDNA gene promoter methylation at individual CpGs across the upstream core element and the core promoter region. A 247-bp DNA segment was amplified and the extent of methylation at 23 of 29 CpG sites (−195 to +52 bp) was determined by pyrosequencing using primers A1 to A3. Each square represents a single CpG and each row represents a sample. The extent of methylation is represented over the range of 0% (white) to 100% (dark blue). The heat map was constructed using R software.