Fig. 1

Pedigree and phenotypes information of the four PPD affected pigs. a Pedigree of the three PPD affected pigs and one random case. Squares represent males and circles represent females. Shaded symbols denote polydactyly pigs. b Phenotypes of the affected male (F1-a1) which expressing a preaxial polydactyly on left forelimb. c Affected female (F1-a2) expressing a preaxial polydactyly phenotype on right side of fore limb. d Affected male (F1-a3) appears a preaxial polydactyly phenotype on right side of fore limb. e Affected female (F0–4) appears a preaxial polydactyly phenotype on left forelimb. f Radiograph and phenotype of the affected male (F1-a1). g Radiograph and phenotype of the affected male (F1-a3). The four hooves were placed based on the position of alive pigs, at the front were forelimbs and on the right were right limbs