Contiguous gene deletion neighboring TWIST1 identified in a patient with Saethre-Chotzen syndrome associated with neurodevelopmental delay: Possible contribution of HDAC9.

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.