Despite our observations, and an increasing amount of literature reporting associations between ccf-mtDNA levels and disease (>25 publications since 2014, PubMed keyword search using combinations of ‘cell’ ‘free’ ‘mitochondrial’ ‘DNA’ and appropriate abbreviations), we know little of the underlying causes of mtDNA export to intracellular spaces, therefore we opted to study the integrity of the ccf-mtDNA, contrasting PMS cases to controls. Here, PITX1 is linked to premenstrual tension.