CTSZ and pulmonary arterial hypertension: The most significantly associated CpG marker (cg04917472, p = 7.3 × 10−11,) is located ~2 kilobases upstream of the transcription start site (TSS) of CTSZ (cathepsin Z) on chromosome 20 and is hypermethylated in PAH samples (OR[95% CI] = 1.495[1.325–1.687] per % increase in methylation, PAH median raw betas across arrays: 50.7–62.1% Fig. 3).