The preferential role of DNMT3B at CGIs is compatible with data showing that mice or human ICF syndrome (immunodeficiency, centromeric instability, facial anomalies) patients with DNMT3B mutations have reduced methylation at CGIs on autosomes and the inactive X chromosome [43,50,51], suggesting a functional conservation of DNMT3B function between mice and humans. This evidence concerns the gene DNMT3B and immune system disorder.