Quantitative LINE1 bisulfite pyrosequencing. (A) Example of LINE1 pyrogram. The percentage of C and T (corresponding to methylated and unmethylated cytosine, respectively) are shown in boxes above each CpG site (gray shading). Overall LINE1 methylation is estimated from the average proportion of C across 4 CpG sites. (B) LINE1 methylation at 4 CpG sites in hematopoietic cells from 12 healthy controls and 21 JMML cases. The JMML cases are grouped into 8 cases with normal CpG island methylation (patients A054, CH017, D097, D116, D257, D454, D675, and SC102) and 8 cases with hypermethylation in at least 3 of 4 CpG islands (patients D020, D127, D360, D361, D397, D567, D684, and PL019).