Monarch Disease Ontology id MONDO_0015730 (mosaic trisomy 17) is a rare chromosomal anomaly syndrome, with a highly variable clinical presentation, mostly characterized by growth delay, intellectual disability, body asymmetry with leg length differentiation, scoliosis, and congenital heart anomalies (e.g. ventricular septal defect). Prenatal ultrasound findings include intrauterine growth retardation, nuchal thickening brain anomalies (e.g. cerebellar hypoplasia), pleural effusion and single umbilical artery. Patients with no associated malformations have also been reported. Also known as: Mosaic trisomy chromosome 17, Mosaic trisomy type 17, trisomy 17 mosaicism.