Based on the hypothesis that zinc imbalance disturbs DNA methylation, zinc deficiency or excess might lead to similar phenotypes to those characterizing the human genetic disorders, ICF (immunodeficiency, centromeric instability and facial anomalies) syndrome and Rett syndrome, associated to mutations in the DNMT3B and MECP2 gene, respectively35. Here, DNMT3B is linked to atypical Rett syndrome.