GRHPR and osteogenesis imperfecta: 1999). Mutations creating uAUGs have subsequently been described and functionally tested in 12 other human disorders (reviewed by Barbosa et al. 2013). In all these cases, the uORFs generated by the novel uAUGs reduced protein expression from the normal ORF to 30% or less. Two further examples of novel uAUGs compromising translation at the normal start site were reported: in the IFITM5 gene in osteogenesis imperfecta (Cho et al. 2012; Semler et al. 2012), and in the GRHPR gene in primary hyperoxaluria type II (Fu et al. 2015).