At present, over 190 cases with mutations and deletions involving the ZEB2 gene have been reported, but triplication or duplication of reciprocal region of Mowat-Wilson syndrome has never been reported.<h4>Case presentation</h4>Here we report a 2-year-2-month-old boy carrying a de novo 2.9 Mb complex copy number gain at 2q22.3 involving triplication of ZEB2 gene. The gene discussed is ZEB2; the disease is Mowat-Wilson syndrome.