These mice develop cardiac hypertrophy, diminished heart function, fibrosis, a reduction in mitochondrial content, and diminished levels of acylcarnitine at 12 months of age.31 Diminished mitochondrial content is associated with the strong reduction of a mitochondrial CIV marker, which is in line with a degradation of Mt-co1 and Cox4i1 in Prdm16csp1/wt hearts. Here, COX4I1 is linked to cardiac hypertrophy.