Our results also failed to identify any duplication of the 15q11-q13 or 22q11.2 regions. Maternally-derived duplications of chromosome 15q11-q13, involving the region deleted in PWS and Angelman syndrome, confer a high risk of autism spectrum disorder or autistic features, whereas paternal inheritance usually leads to a normal phenotype or mild developmental delay [31,32]. Recent technical progresses have lead to the identification of new chromosomal microrearrangements, including the reciprocal duplications of 22q11.2 deletions [33,34]. 22q11.2 microduplications are characterized by highly variable and subtle phenotypes. The majority of individuals have cognitive deficits including speech delay and developmental delay [33,35]. In addition, 22q11.2 microduplications can be inherited from relatives with no distinctly recognizable phenotype, suggesting reduced penetrance [36]. OCD or obsessive-compulsive symptoms have not been reported in individuals with the 15q11-q13 duplication syndrome or the 22q11.2 duplication syndrome, but given the recent identification of the latter syndrome and the limited number of patients described [33-35,37], further studies are needed.
