Hedgehog Homolog, Indian (IHH)

IHH is one of three proteins in the mammalian hedgehog family, the others being desert hedgehog (DHH) and Sonic hedgehog (SHH). It is involved in chondrocyte differentiation, proliferation and maturation especially during endochondral ossification. It regulates its effects by feedback control of parathyroid hormone-related peptide (PTHrP).Gao et al. (2001) decided to focus on IHH as the gene implicated in brachydactyly type A1 because of its position in the implicated interval on chromosome 2q35-q36 flanked by markers D2S2248 and D2S360 and becauseIHH is known to mediate condensation, growth, and differentiation of cartilage. They identified 3 heterozygous missense mutations in the region encoding the amino-terminal signaling domain in all affected members of 3 large, unrelated Chinese families.