8p23.1 duplication syndrome is a rare chromosomal anomaly syndrome, resulting from the partial duplication of the short arm of chromosome 8, with a highly variable phenotype, principally characterized by mild to moderate developmental delay, intellectual disability, mild facial dysmorphism (incl. prominent forehead, arched eyebrows, broad nasal bridge, upturned nares, cleft lip and/or palate) and congenital cardiac anomalies (e.g., atrioventricular septal defect). Other reported features include macrocephaly, behavioral abnormalities (e.g., attention deficit disorder), seizures, hypotonia and ocular and digital anomalies (poly/syndactyly).

Webbing or fusion of the toes, involving soft parts only or including bone structure. Bony fusions are referred to as \"bony\" Syndactyly if the fusion occurs in a radio-ulnar axis. Fusions of bones of the toes in a proximo-distal axis are referred to as \"Symphalangism\".