We demonstrate that the genetic associations at PPM1K with the BCAA catabolites 2-aminobutyrate, isobutyrylcarnitine and gamma-glutamyl-2-aminobutyrate colocalize (PP = 0.98) with the association with breast cancer (Methods and Extended Data Fig. 6), supporting a role for BCAA catabolism in breast cancer etiology44. This evidence concerns the gene PPM1K and breast cancer.