MTHFR 1298 variant showed strong significant results in the whole cohort of children, and CC-homozygotes had a significant delay in ALL onset (8.03 ± 4.8 years; P = 0.006) when compared with AA-homozygotes (5.7 ± 4.15 years). The gene discussed is MTHFR; the disease is acute lymphoblastic leukemia.