Polydactyly, also known as hyperdactyly, is a condition that causes a person to be born with extra fingers or toes. It's one of the most common birth defects that affects hands and feet, affecting about one in every 500 to 1,000 babies. The extra digits are usually small and abnormally developed, and are often present on both hands or both feet. What to Know About Polydactyly - WebMD Feb 16, 2024 — Polydactyly is the term for when someone has extra digits, or fingers or toes.

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