An atypical 0.8 Mb inherited duplication of 22q11.2 associated with psychomotor impairment

Microduplications 22q11.2 have been recently characterized as a new genomic duplication syndrome showing an extremely variable phenotype ranging from normal or mild learning disability to multiple congenital defects and sharing some overlapping features with DiGeorge/velocardiofacial syndrome (DGS/VCFS), including heart defects, urogenital abnormalities and velopharyngeal insufficiency. We present an atypical and inherited 0.8-Mb duplication at 22q11.2, in the distal segment of the DGS/VCFS syndrome typically deleted region (TDR), in a 3-year-old boy with motor delay, language disorders and mild facial phenotype. This 22q11.2 microduplication was identified by MLPA, designed to detect recurrent microdeletions and microduplications of chromosomal regions frequently involved in mental retardation syndromes and was further characterized by aCGH. The duplicated region encompasses 14 genes, excluding TBX1 but including CRKL, ZNF74, PIK4CA, SNAP29 and PCQAP known to contribute to several aspects of the DGS/VCFS phenotype. To the best of our knowledge, only one case of an isolated duplication in the distal segment of the TDR between chromosome 22-specific low-copy repeats B (LCR22-B) and D (LCR22-D) has been published, but the present report is the first one with a detailed description of physical and developmental features in a patient carrying this kind of atypical 22q11.2 duplication. This case illustrates the importance of reporting unusual 22q11.2 duplications to further evaluate the incidence of these rearrangements in the general population and to improve genotype-phenotype correlations and genetic counseling.