In Reply We thank Chao and colleagues for their comments regarding our article.¹ Referring to the recent article that showed the median plasma coenzyme Q10 (CoQ10) level in 141 healthy Japanese individuals to be 1.02 µg/mL,² which was much higher than that in our study (0.72 µg/mL), they suggested that the difference in the plasma CoQ10 level between patients with multiple system atrophy (MSA) and controls may be much larger than previously reported. To date, 2 groups from Japan have shown decreased plasma CoQ10 levels in patients with MSA.^1,3 As noted by Chao and colleagues, the sample sizes in those studies were relatively small; hence, it will be important to determine plasma CoQ10 levels in much larger sample sizes. They also mentioned that cholesterol levels should be taken into account in evaluating CoQ10 levels because plasma cholesterol levels affect CoQ10 levels by forming a conjugated form. We admit that we did not include plasma cholesterol levels in our study. However, Kasai et al³ reported that the CoQ10 to total cholesterol ratios are significantly decreased in patients with MSA (mean [SD], 3.04 [1.23]) compared with those in controls (mean [SD], 5.92 [5.88]). Furthermore, 2 groups from the United Kingdom and United States have reported decreased CoQ10 levels in the cerebellum of patients with MSA.^4,5 Thus, decreased CoQ10 levels in patients with MSA are consistent findings. Although the association of the COQ2 V393A variant with MSA has been demonstrated in East Asian populations,⁶ the entire mechanisms underlying decreased CoQ10 levels remain to be elucidated in detail.