A moderate decrease in all‐titin phosphorylation vs. control hearts was detected in RV samples from patients with PAH 113 and in LV samples from patients with severe chronic HF due to hypertrophic cardiomyopathy (HCM) 87, as well as in endomyocardial LV biopsies from patients with severe aortic stenosis (AS) 114. The gene discussed is TTN; the disease is pulmonary arterial hypertension.