7p22.1 microduplication syndrome : refinement of the critical region

7p22.1 microduplication syndrome is mainly characterized by developmental and speech delay, craniofacial dysmorphisms and skeletal abnormalities. The minimal critical region includes two OMIM genes: ACTB and RNF216. Here, we report on a girl carrying the smallest 7p22.1 microduplication detected to date, contributing to the delineation of the clinical phenotype of the 7p22.1 duplication syndrome and to the refinement of the minimal critical region. Our patient shares several major features of the 7p22.1 duplication syndrome, including craniofacial dysmorphisms and speech and motor delay, but she also presents with renal anomalies. Based on present and published dup7p22.1 patients we suggest that renal abnormalities might be an additional feature of the 7p22.1 microduplication syndrome. We also pinpoint the ACTB gene as the key gene affecting the 7p22.1 duplication syndrome phenotype.