We sought to characterize the phenotypes and identify the SEC24D gene mutations 
associated with Chinese families of osteogenesis imperfecta (OI). Using 
whole-exome sequencing, we discovered two novel compound SEC24D mutations of OI 
patients. Our study extended both the phenotypic and the genotype of the OI 
patients with SEC24D mutations.
INTRODUCTION: To date, only three compound heterozygous mutations in the SEC24D 
gene have been found to cause recessively inherited forms of OI. We sought to 
characterize the phenotypes and to identify the SEC24D gene mutations associated 
with Chinese families with OI.
METHODS: Using whole-exome sequencing in two probands, we identified two novel 
compound heterozygous mutations in SEC24D. In family 1, the proband was a 
23-year-old male; he had recurrent fractures and dentinogenesis imperfecta. His 
anterior fontanel was not closed, and he showed facial dysmorphism. A computed 
tomography three-dimensional imaging of the cranium showed skull deformities 
associated with a broad ossification defect in the frontoapical area, a widened 
sagittal suture, and Wormian bones. In family 2, the proband was a 7-year-old 
boy, who also had recurrent fractures and dentinogenesis imperfecta. His 
anterior fontanel was not closed, and he did not have obvious facial 
dysmorphism.
RESULTS: We identified one novel compound heterozygous missense substitution in 
the proband in family 1, including c.2723G>A (p. Cys908Tyr) and c.2842T>C (p. 
Ser948Pro). In the proband in family 2, we identified another novel compound 
heterozygous missense substitution, including c.938G>A (p. Arg313His) and 
c.875C>T (p. Pro292Leu).
CONCLUSIONS: We discovered two novel compound SEC24D mutations of autosomal 
recessive OI patients. Our study extended both the phenotypic and the genotypic 
spectrum of the autosomal recessive OI patients with SEC24D mutations.