Decreases in ATP content are consistent with an impairment of oxidative phosphorylation, and cardiac mitochondria isolated from a mouse model of BTHS due to doxycycline mediated Taz knockdown (herein referred to as TazKD mice), display markedly reduced respiration, primarily attributed to impaired complex III activity (Kiebish et al., 2013; Powers et al., 2013). The gene discussed is TAFAZZIN; the disease is Barth syndrome.