In most cases, duplication 12p phenotype is characterized bydysmorphic features, multiple congenital anomalies and intellectual disability.A small number of cases in literature have described genes associated withneurodevelopmental disease, such as ING4,CHD4, MFAP5, GRIN2B, SOX5,SCN8A and PIANP. In our patient theduplication 12p was de novo. The gene discussed is MFAP5; the disease is glycogen storage disease VI.