The mRNA levels of Col1α1 and Col3α1 and hydroxyproline concentration in the RV were also greatly upregulated under chronic HAH, whereas no similar change occurred in the LV, revealing that hypoxia increased collagen content and promoted myocardial fibrosis in the RV (Watson et al., 2014). The gene discussed is COL1A1; the disease is Myocardial fibrosis.