Rett syndrome (RTT) and Angelman syndrome (AS) are devastating neurological disorders that participate in overlapping clinical features with autism spectrum disorders (ASDs). It has been reported that in addition to common mutations or deletions, individuals with chromosomal duplications including either the MECP2 or UBE3A loci show clinical features related to those of MECP2 duplication syndrome, AS, or ASDs. Here we report a 10-year--10-months old male patient having overlapping clinical features of MECP2 duplication syndrome, AS and ASDs. He had mental retardation, lack of speech and developmental delay, and also dysmorphic features such as plagiocephaly, retrognathia, hyperextensible joints in fingers and elbows, broad great toe and three different sizes of cafe au laits. The X-ray revealed compound craniosynostosis and the cranial MRI at 10 years showed delayed myclination. Due to his clinical features, we performed molecular karyotyping and found numerous genomic alterations. Two of these genomic alterations including duplications of chromosome Xq28 and 15qll.2ql3.l1 were found to be compatible with his clinical findings. According to methylation analysis, duplicated UBE3A gene found to be not methylated. The present case study may contribute to a better definition and an improved comprehension of the overlapping pathways of MECP2 and UBE3A.