MECP2 protein suppresses IGFBP3 gene expression, so MECP2 dysfunction leads to increased expression of IGFBP3. Mice with artificial Igfbp3 overexpression have phenotype somewhat similar to Mecp2-null mice and some features in their CNS development resemble Rett syndrome pathologies. The gene discussed is IGFBP3; the disease is atypical Rett syndrome.