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17q23.1q23.2 microdeletion syndrome
17q23.1q23.2 microdeletion syndrome is a recently described syndrome characterized by developmental delay, microcephaly, short stature, heart defects and limb abnormalities.
It has been clinically and molecularly characterized in 7 patients.
All individuals had mild to moderate developmental delay, in particular speech delay. All except one had heart defects, including mainly patent ductus arteriosus or atrial septal defect. Limb abnormalities include long, thin fingers and toes, and hypoplasia of patellae. Scoliosis is also present. Patients had some mild and unspecific dysmorphic facial features.
The syndrome is caused by an interstitial deletion encompassing 17q23.1q23.2. The deletions were characterized by comparative genomic hybridization (CGH) microarray and fluorescence in situ hybridization (FISH). The underlying mechanism is non-allelic homologous recombination (NAHR). Parental FISH testing in five of the seven cases confirmed a de novo origin. The minimal deletion region of 2.2 Mb encompasses 2 transcription factors, TBX2 and TBX4, which are good candidate genes for explaining the phenotype.