Figure 2. Schematic representation of the CFTR gene (exon-intron structure) showing the promoter (P) and three enhancers located 35-kb 5′ (upstream) from the gene (E-35), in intron 1 (E1) and intron 11 (E11). Zoom on the 5′ region where DNA methylation was analyzed by either bisulfite and genomic sequencing (BGS), or next-generation sequencing (NGS), or pyrosequencing (PS). The three assays measured methylation in 29, 10, and 6 overlapping CpG dinucleotides, respectively. TSS is the transcription start site, and ATG is the first methionine codon. Shown are the hg19 coordinates of the analyzed regions.