The extent of hypertrophy was determined by quantitative real-time PCR (qRT-PCR) for 5 hypertrophy markers: Nppa, Nppb, Myh7, Acta1, and Pln. Although the hypertrophied hearts had similar appearances, the expression levels of the markers significantly differed between the PHH and PAH mice. The gene discussed is ACTA1; the disease is pulmonary arterial hypertension.