It is well-established that DNA demethylation caused by DNMT deficiency induces aneuploidies: in Dnmt1 hypomorphic cells in vivo80,81, in peripheral T cell lymphomas arising from haematopoietic stem/precursor cells conditionally disrupted for Dnmt3a82,83 and in Dnmt3b deficiency mimicking ICF syndrome (immunodeficiency, centromere instability and facial abnormalities) in vivo84. This evidence concerns the gene DNMT1 and immune system disorder.