The Ala140Asp (rs4925) polymorphism in GSTO-1 has been the most widely-studied, linked to risk of pre-cancerous skin lesions and cancer in arsenic-exposed populations [26,52,53], however studies have not confirmed any association between specific variants in GSTO-1 with the relative proportion of arsenic and its metabolites [47,52,54]. The gene discussed is GSTO1; the disease is cancer.