Osteogenesis imperfecta (OI) is a rare heritable skeletal disorder which is mainly caused by defected type I collagen. Autosomal recessive OI (AR-OI) is caused by mutations of genes that are responsible for type I collagen modification and folding, and is often associated with more severe phenotypes. Due to the limited number of recessive OI patients, it has been difficult to study the mutation spectrum as well as the correlation of genotype and phenotype. This study recruited a Chinese cohort of 74 AR-OI families, aiming to establish the mutation spectrum and to examine the genotypic and phenotypic correlation. We identified 82 variants including 25 novel variants and 57 HGMD reported variants in these AR-OI patients, using whole exome sequencing/panel sequencing combined with Sanger sequencing. Pathogenic mutations were found at WNT1 (n = 30, 40.54%), SERPINF1 (n = 22, 29.73%), FKBP10 (n = 10, 13.51%), CRTAP (n = 3, 4.05%), P3H1 (n = 3, 4.05%), SERPINH1 (n = 2, 2.70%), SEC24D (n = 3, 4.05%), and PLOD2 (n = 1, 1.35%) respectively. Thus, WNT1 represents the most frequent pathogenic gene of AR-OI in Chinese population. The most common clinical manifestations of AR-OI patients include walking problem (72.86%), scoliosis (65.28%) and frequent fractures (fractures ≥2/year) (54.05%). Interestingly, ptosis represents a unique phenotype of patients carrying WNT1 variants, and it was rare in patients harboring other pathogenic genes. Our study expanded the mutation spectrum of AR-OI and enriched the knowledge of genotypic and phenotypic correlation in Chinese cohort with AR-OI.

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