Saethre-Chotzen syndrome (SCS) is an autosomal dominant craniosynostotic 
disorder characterized by coronal synostosis, facial asymmetry, ptosis, and limb 
abnormalities. Haploinsufficiency of TWIST1, a basic helix-loop-helix 
transcription factor is responsible for SCS. Here, we report a 15-month-old male 
patient with typical clinical features of SCS in addition to developmental 
delay, which is a rare complication in SCS. He showed a de novo 0.9-Mb 
microdeletion in 7p21, in which TWIST1, NPMIP13, FERD3L, TWISTNB, and HDAC9 were 
included. In comparison with previously reported patients, HDAC9 was suggested 
to contribute to developmental delay in SCS patients with 7p21 mirodeletions.