The variants MTRR p.I49M and NAT2*6 are less frequent in individuals from Groups 1 and 4 (those with a greater degree of NA ancestry) and could predict a reduction in toxicity in cancer patients treated with methotrexate, reduce the risk of hepatotoxicity in tuberculosis patients, and the risk in its use for treatment of acute lymphoblastic leukemia (Gast et al., 2007; Huang et al., 2008), for which it is one of the main drugs used in Mexico (Medellin-Garibay et al., 2019). Here, NAT2 is linked to cancer.