• A congenital anomaly of the hand or foot, marked by the webbing between adjacent fingers or toes. Syndactylies are classified as complete or incomplete by the degree of joining. Syndactylies can also be simple or complex. Simple syndactyly indicates joining of only skin or soft tissue; complex syndactyly marks joining of bony elements.
  NLM Medical Subject Headings
  U.S. National Library of Medicine, 2025
• A congenital condition characterized by webbing between the fingers and/or toes, joining the digits together. In rare cases, the joining of the fingers or toes may involve bony fusion between the digits. Common causes include Down Syndrome and hereditary syndactyly.
  NCI
  U.S. National Cancer Institute, 2021
• Webbing or fusion of the fingers or 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 fingers or toes in a proximo-distal axis are referred to as "symphalangism"." [https://orcid.org/0000-0002-0736-9199]
  Human Phenotype Ontology (HPO)
  The Human Phenotype Ontology Project, 2025
• Syndactyly is the most common congenital malformation of the limbs, with an incidence of 1 in 2000-3000 live births. Syndactyly can be classified as simple when it involves soft tissues only and classified as complex when it involves the bone or nail of adjacent fingers.
  Medscape
  WebMD, 2025
• Syndactyly is a term used to describe webbed or conjoined digits (fingers or toes). It may occur as an isolated finding or may be a symptom of a genetic syndrome. There are over 300 genetic syndromes that involve syndactyly, such as Apert syndrome and Saethre-Chotzen syndrome. There are many different ways to classify or group...
  NIH Genetic and Rare Diseases
  National Center for Advancing Translational Sciences