BMPR2 and pulmonary arterial hypertension: Approximately 75% of BMPR2 mutations linked to PAH are heterozygous nonsense mutations that are caused either by frame-shift deletions or insertions, whereby a premature translation codon (PTC) is inserted into the DNA sequence, resulting in an unstable mRNA transcript that is quickly degraded by nonsense-mediated decay (NMD) with complete absence of the mutant protein [137].