Therefore, the DNA hypomethylation and chromosomal abnormalities in mice with Dnmt3b mutations or derived cell cultures is more extensive (including centromeric as well as juxtacentromeric DNA) than in the DNMT3B-mutant ICF syndrome in humans, even when comparing the same DNMT3B mutations, and the nature of the immune dysfunction is different. This evidence concerns the gene DNMT3B and ICF syndrome.