4p16.3 microduplication syndrome is a rare genetic syndrome that results from the partial duplication of the short arm of chromosome 4. It has a highly variable phenotype, principally characterized by psychomotor and language delay, seizures and dysmorphic features such as high forehead with frontal bossing, hypertelorism, prominent glabella, long narrow palpebral fissures, low set ears and short neck. Eye abnormalities (glaucoma, irregular iris pigmentation, hyperopia) have also been reported. The disease is MONDO_0019873 (4p16.3 microduplication syndrome). Also known as: distal duplication 4p, distal trisomy 4p, telomeric duplication 4p, trisomy 4pter.