PITX1 and premenstrual tension: However we found no significant difference in ccf-mtDNA deletion levels between PMS cases and controls (Wilcoxon Ranked Sum Test p > .05, Fig. 2a) and no significant correlation (p > .05) between ccf-mtDNA deletion level and age at death, brain weight, post mortem interval (in either PMS cases, controls or when combined) or age of onset (PMS cases only) (Supplementary Table 2).