In contrast, the positive association of ccf-mtDNA with brain structure in BD may reflect the beneficial characteristics of ccf-mtDNA, namely intracellular communication, rescue of mitochondrial biogenesis pathways (Nicolás-Ávila et al. 2020), and clearance of damaged mitochondria (Davis et al. 2014). The gene discussed is PITX1; the disease is Behcet disease.