RMRP and cartilage-hair hypoplasia: Germ-line point-mutations, insertions, and duplications reducing RMRP expression cause the recessively inherited disorder “cartilage-hair hypoplasia” (CHH), which is primarily associated with abnormalities in bone and cartilage development (Ridanpaa et al., 2001; Martin and Li, 2007; Nakashima et al., 2007).