However, ultimately, we saw no significant correlation between vCSF ccf-mtDNA and the levels of S100β, GFAP, CHI3L1, CHI3L2 or CHI3L1:CHI3L2 ratio when analysed as PMS cases only or controls only, or when combined (Supplementary Table 2). This evidence concerns the gene CHI3L2 and premenstrual tension.