Phenotypes associated with the disease polydactyly of a triphalangeal thumb (OMIM:174500):
- Preaxial hand polydactyly (HP:0001177): Supernumerary digits located at the radial side of the hand. Polydactyly (supernumerary digits) involving the thumb occurs in many distinct forms of high variability and severity. Ranging from fleshy nubbins over varying degrees of partial duplication/splitting to completely duplicated or even triplicated thumbs or preaxial (on the radial side of the hand) supernumerary digits. Evidence: PCS. Frequency: Very frequent (HP:0040281). (PMID:18178630)
- Complete duplication of distal phalanx of the thumb (HP:0009606): Complete duplication of the distal phalanx of the thumb. On x-ray two separate bones appear side to side. Evidence: TAS. (OMIM:174500)
- Postaxial hand polydactyly (HP:0001162): Supernumerary digits located at the ulnar side of the hand (that is, on the side with the fifth finger). Evidence: PCS. Frequency: Frequent (HP:0040282). (PMID:18178630)
- Duplication of phalanx of hallux (HP:0010066): Partial or complete duplication of one or more phalanx of big toe. Evidence: TAS. Frequency: Frequent (HP:0040282). (OMIM:174500)
- Duplication of thumb phalanx (HP:0009942): Complete or partial duplication of the phalanges of the thumb. Depending on the severity, the appearance on x-ray can vary from a notched phalanx (the duplicated bone is almost completely fused with the phalanx), a partially fused appearance of the two bones (bifid), two separate bones appearing side to side, or completely duplicated phalanges (proximal and distal phalanx of the thumb and/or 1st metacarpal). In contrast to the phalanges of the digits 2-5 (proximal, middle and distal), the proximal phalanx of the thumb is embryologically equivalent to the middle phalanges of the other digits, whereas the first metacarpal is embryologically of phalangeal origin and as such equivalent to the proximal phalanges of the other digits. Evidence: TAS. Frequency: Very frequent (HP:0040281). (OMIM:174500)
- Preaxial foot polydactyly (HP:0001841): Duplication of all or part of the first ray. Evidence: PCS. Frequency: Frequent (HP:0040282). (PMID:18178630)
- Postaxial foot polydactyly (HP:0001830): Polydactyly of the foot most commonly refers to the presence of six toes on one foot. Postaxial polydactyly affects the lateral ray and the duplication may range from a well-formed articulated digit to a rudimentary digit. Evidence: PCS. Frequency: Frequent (HP:0040282). (PMID:18178630)
- Syndactyly (HP:0001159): 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". Evidence: PCS. Frequency: Frequent (HP:0040282). (PMID:18178630)
- Autosomal dominant inheritance (HP:0000006): A mode of inheritance that is observed for traits related to a gene encoded on one of the autosomes (i.e., the human chromosomes 1-22) in which a trait manifests in heterozygotes. In the context of medical genetics, an autosomal dominant disorder is caused when a single copy of the mutant allele is present. Males and females are affected equally, and can both transmit the disorder with a risk of 50% for each child of inheriting the mutant allele. Evidence: PCS. (PMID:12837695)
- Opposable triphalangeal thumb (HP:0005866): A form of triphalangeal thumb that can be placed opposite the fingers of the same hand. Evidence: PCS. Frequency: Very frequent (HP:0040281). (OMIM:174500)