HOXD13 and Huntington disease: In another study, no obvious limb malformations were noted in the individuals with a heterozygous HOXD13 missense mutation c.938C>G (p.T313R) or T46R in HD, but the homozygotes of T46R result in a severe SPD with metacarpal to carpal transformation.35 However, in our mouse model, all heterozygotes showed shortened digits, while some exhibited syndactyly and polydactyly, displaying different pheontypes campared to SDTY5 patients.