A rare chromosomal anomaly syndrome resulting from the partial duplication of the long arm of chromosome 1. The syndrome has a highly variable phenotype and principle characteristics of intellectual disability, short stature, craniofacial dysmorphism (including macro/microcephaly, prominent forehead, posteriorly rotated, low-set ears, abnormal palpebral fissures, microphthalmia, broad, flat nasal bridge, high-arched palate, micro/retrognathia), cardiac defects and urogenital anomalies. Patients may also present cerebral (for example ventriculomegaly) and gastrointestinal malformations, as well as dystonic tremor and recurrent respiratory tract infections. [from
SNOMEDCT_US]