Microdeletions of chromosome 7p21, including TWIST1, associated with significant microcephaly, facial dysmorphism, and short stature.

Saethre-Chotzen syndrome due to TWIST1 mutations is characterized by coronal synostosis, facial dysmorphism and additional variable anomalies. Small deletions comprising the whole TWIST1 account for a small proportion of patients with Saethre-Chotzen syndrome. Here we describe 3 patients with facial dysmorphism, marked microcephaly, short stature (2/3 patients), and overlapping 7p21 microdeletions. Molecular karyotyping identified small deletions of chromosome 7p21 including TWIST1 with a size of 526 kb, 9.2 Mb, and 11.7 Mb, respectively. The clinical manifestations of these patients do not resemble the typical phenotype of Saethre-Chotzen syndrome. In the two patients with larger microdeletions, severe mental retardation and significant short stature are present. Facial dysmorphism of patient 3 includes also signs of blepharophimosis-ptosis-epicanthus inversus syndrome.