POLG and cardiac hypertrophy: Transgenic mice for a cardiac-specific mutant of Polg (termed Y955C) develop LV hypertrophy at 94 days of age[160], while mice with a homozygous mutation in the encoding domain (D257A) of a proofreading deficient version of Polg develop biventricular hypertrophy at 10–12 months of age[161].