Polydactyly of an index finger or PPD3 is a form of preaxial polydactyly of fingers, a limb malformation syndrome, where the thumb is replaced by one or two triphalangeal digits with dermatoglyphic pattern specific of the index finger. Two forms of PPD3 have been characterized: unilateral and bilateral. There have been no further descriptions in the literature since 1962. The disease is polydactyly of an index finger (MONDO_0008271, a Monarch Disease Ontology term). Also known as: PPD3, polydactyly, preaxial type 3, preaxial polydactyly type 3.