Abstract: Objective To investigate the phenotype of a boy with osteogenesis imperfecta (OI) and detect the pathogenic gene mutation in his family. Methods The clinical data of a uygur ethnic boy was investigated in detail, who suffered from early onset repeated fragile fractures. Bone turnover biomarkers, bone mineral density (BMD) and bone morphology were evaluated. The pathogenic mutations in this patient were investigated by targeted next-generation sequencing and subsequently confirmed by Sanger sequencing. Results Serum β-cross linked C-telopeptide of type I collagen was elevated. Radiological assessment revealed generalized osteoporosis in thoracolumbar spine, slender long bone with thin cortices. The pathogenic mutations in TMEM38B were detected as follow: a homozygous mutation c.507G>A transition in exon 4, which would generate a new downstream termination codon (p.W169X). His parents were heterozygous carriers of the mutation. Conclusion Mutation in TMEM38B is identified for the first time in a uygur ethnic boy with extremely rare autosomal recessive OI type XIV. The clinical and genetic findings extend our understanding of rare OI induced by TMEM38B mutation.

Key words: osteogenesis imperfecta, TMEM38B mutation, calcium homeostasis