In light of our results with R237C, and since prior work suggested an association between amyotrophic lateral sclerosis (a.k.a., Lou Gehrig’s Disease) and reduced-function APE1 variants (e.g., L104R,, E126D and D283G) [33], we searched for disease-associated variation in APE1 in 62 human cancer cell lines. Here, APEX1 is linked to amyotrophic lateral sclerosis.