Luongo et al. found that the mitochondrial Na+/Ca2+ exchanger (NCLX) was essential for Ca2+ homeostasis and viability. Here, we re-analyze their data in terms of fractal self-similarity and quantitative difference (QD). We calculated the 7-dimension data from NCLX conditional loss-of-function mouse models, and the 9-dimension data from NCLX overexpression (NCLX-Tg) models. Results: The 9-dimension data of the NCLX-Tg and its tTA control were partially self-similar to each other, while the 7-dimension data in NCLX knockout models were not.Conclusion: The NCLX may be necessary but is not sufficient for Ca2+ homeostasis and viability.