IHH and acrocapitofemoral dysplasia: To date, only three homozygous missense mutations [c.137C>T; p.(Pro46Leu), c.569T>C; p.(Val190Ala), c.478C>T; p.(Arg160Cys)] have been reported in the signaling amino terminal domain of the IHH gene in three ACFD families from Belgian, Dutch, and Turkish ethnicities (Hellemans et al. 2003; Cubuk and Duz 2021).