We measured the levels of oxidized DNA bases in wild-type and NTH-1-deficient PD nematodes during aging by liquid chromatography-tandem mass spectrometry (LC-MS/MS) (Figure 5A) and by immunohistochemical staining with anti-8-oxoG antibodies (Figure 5B; Figure S7A). Here, NTHL1 is linked to Parkinson disease.