Monarch Disease Ontology term MONDO_0015718 (mosaic trisomy 12) is a rare chromosomal anomaly syndrome, with a highly variable phenotype, principally characterized by developmental or growth delay, short stature, craniofacial dysmorphism (e.g. turricephaly, tall forehead, downslanting palpebral fissures, posteriorly rotated and low set ears, narrow palate), congenital heart defects (e.g. atrial septal defect, patent ductus arteriosus), hypotonia, and pigmentary dysplasia. Scoliosis, hearing loss, facial/body asymmetry, and intellectual disability have also been reported. Also known as: Mosaic trisomy chromosome 12, Mosaic trisomy type 12, trisomy 12 mosaicism.