Fig. 4

Frequency of mtDNA heteroplasmic mutations in cortical regions increases with age. (A) Histogram depicts the number of mtDNA heteroplasmic mutations detected per sample in each of the four studied brain regions. (B) Circular plot of the mitochondrial genome shows the genome annotation on the outer circle. The four inner circles show the genomic locations and the relative frequencies (y-axis) of mtDNA heterplasmic mutations detected in each of the four brain regions. (C-E) Scatter plots showing the relation between age and mtDNA heteroplasmy burden in the DLPFC (C), in the TCX (D), and in the FP (E). Some jitter was added before plotting the points to avoid overlapping points. Regression curves and p values were obtained from quasi-Poisson regression models with the number of mtDNA heteroplasmic mutations as outcome and age as independent variable. In the TCX and FP, age was grouped into 5-year strata because of censored data. (F) Table shows the effect sizes of age on mtDNA heteroplasmy burden obtained from the Quasi-Poisson regression models depicted in panels (C-E). The 95% confidence intervals are shown in brackets