A study claims that high doses of vitamin C can possibly stop the progression of lethal blood cancer. Vitamin C encourages faulty stem cells in the bone marrow to die, claims the study. Certain genetic changes are known to reduce the ability of an enzyme called TET2 to encourage stem cells to become mature blood cells, which eventually die, in many patients with certain kinds of leukaemia, researchers said. “We are excited by the prospect that high-dose vitamin C might become a safe treatment for blood diseases caused by TET2-deficient leukaemia stem cells, most likely in combination with other targeted therapies,” said Benjamin Neel, professor at New York University (NYU) in the US. Changes in the genetic code (mutations) that reduce TET2 function are found in 10 per cent of patients with acute myeloid leukaemia (AML), 30 per cent of those with a form of pre-leukaemia called myelodysplastic syndrome, and in nearly 50 per cent of patients with chronic myelomonocytic leukaemia. Such cancers cause anaemia, infection risk, and bleeding as abnormal stem cells multiply in the bone marrow until they interfere with blood cell production, with the number of cases increasing as the population ages. Researchers studied the relationship between TET2 and cytosine, one of the four nucleic acid “letters” that comprise the DNA code in genes. To determine the effect of mutations that reduce TET2 function in abnormal stem cells, the team genetically engineered mice such that the scientists could switch the TET2 gene on or off. They found that similar to the naturally occurring effects of TET2 mutations in mice or humans, using molecular biology techniques to turn off TET2 in mice caused abnormal stem cell behaviour. These changes were reversed when TET2 expression was restored by a genetic trick. Previous studies had shown that vitamin C could stimulate the activity of TET2 and its relatives TET1 and TET3.