11p15.4 microduplication syndrome is a rare partial autosomal trisomy/tetrasomy characterized by obesity, global developmental delay and intellectual disability, facial dysmorphism (synophrys, high-arched eyebrows, large posteriorly rotated ears, upturned nose, long smooth philtrum, overbite and high palate), large hands and limb hypotonia. Additional features include seizures and behavioral abnormalities. The disease is 11p15.4 microduplication syndrome (MONDO_0017580, a Monarch Disease Ontology term). Also known as: dup(11)p(15.4), trisomy 11p15.4.