Synpolydactyly (SPD) is a joint presentation of syndactyly (fusion of digits) and polydactyly (production of supernumerary digits).[1][2] SPD affects both hands and feet, often occurring symmetrically on both body sides.[3] This is often a result of a mutation in the HOXD13 gene,[2] as HOXD genes are necessary in early limb bud development and specification of the limbs.[4]
^Goodman FR, Mundlos S, Muragaki Y, et al. Synpolydactyly phenotypes correlate with size of expansions in hoxd13 polyalanine tract. Proceedings of the National Academy of Sciences. 1997;94(14):7458-7463. doi:10.1073/pnas.94.14.7458
^Xu W, Graham EM, Shubinets V, Mendenhall SD, Chang B, Lin IC. An evolution of the surgical management of Synpolydactyly. Annals of Plastic Surgery. 2023;90(6S). doi:10.1097/sap.0000000000003513
^Kurban M, Wajid M, Petukhova L, Shimomura Y, Christiano AM. A nonsense mutation in the HOXD13 gene underlies synpolydactyly with incomplete penetrance. Journal of Human Genetics. 2011;56(10):701-706. doi:10.1038/jhg.2011.84