In other species: rock pigeon , chicken , turkey , dog , domestic cat , domestic horse , pig , Arabian camel , guanaco , llama , Western roe deer , taurine cattle , goat , sheep , domestic guinea pig , alpaca , springbok

Categories: Skeleton phene (incl. short stature & teeth) , Limbs / fins / digit / tail phene

Links to possible relevant human trait(s) and/or gene(s) in OMIM: 174500 (trait) , 605522 (gene) , 188740 (trait)

Single-gene trait/disorder: unknown

Disease-related: yes

Cross-species summary: Often called preaxial polydactyly (PPD)

Species summary:  [IT thanks Emma Faull for contributions to this entry in September 2025]

Clinical features: Warburton et al. (2020) reported "a case of extremely unusual bilateral preaxial polydactyly on the pectoral limbs of a male western grey kangaroo (Macropus fuliginosus) from the South West region of Western Australia, in which two supernumerary digits were present on each manus. A supernumerary digit I on each manus was rudimentary in morphology without extrinsic muscular connections. However, supernumerary digit II present on each manus had fully developed extrinsic and intrinsic muscular connections, suggesting that these digits possessed normal function in flexion and extension. An alternative hypothesis is that the two supernumerary digits are both representatives of the most radial digit I, though this would then require the true digit I to have taken on the appearance of digit II by acquiring an additional phalanx and modified muscular attachments."