Figure 1 - Strategy for the methylation-specific PCR based on the methylation pattern of the FMR1 CpG island as described by Stöger et al. (1997). The methylated cytosines are shown in red and marked as asterisks. The non- methylated cytosines are converted into uracil residues (shown in blue) by the bisulfite treatment. This diagram is based on the one published by Zeschnigk et al. (1997) for the diagnosis of Angelman and Prader-Willi syndromes by MSP.