Comprehensive genetic analyses using targeted next-generation sequencing and genotype-phenotype correlations in 53 Japanese patients with osteogenesis imperfecta

Abstract

To elucidate mutation spectrum and genotype-phenotype correlations in Japanese patients with OI, we conducted comprehensive genetic analyses using NGS, as this had not been analyzed comprehensively in this patient population. Most mutations were located on COL1A1 and COL1A2. Glycine substitutions in COL1A1 resulted in the severe phenotype. Introduction Most cases of osteogenesis imperfecta (OI) are caused by mutations in COL1A1 or COL1A2, which encode α chains of type I collagen. However, mutations in at least 16 other genes also cause OI. The mutation spectrum in Japanese patients with OI has not been comprehensively analyzed, as it is difficult to identify using classical Sanger sequencing. In this study, we aimed to reveal the mutation spectrum and genotype-phenotype correlations in Japanese patients with OI using next-generation sequencing (NGS). Methods We designed a capture panel for sequencing 15 candidate OI genes and 19 candidate genes that are associated with bone fragility or Wnt signaling. Using NGS, we examined 53 Japanese patients with OI from unrelated families. Results Pathogenic mutations were detected in 43 out of 53 individuals. All mutations were heterozygous. Among the 43 individuals, 40 variants were identified including 15 novel mutations. We found these mutations in COL1A1 (n = 30, 69.8%), COL1A2 (n = 12, 27.9%), and IFITM5 (n = 1, 2.3%). Patients with glycine substitution on COL1A1 had a higher frequency of fractures and were more severely short-statured. Although no significant genotype-phenotype correlation was observed for bone mineral density, the trabecular bone score was significantly lower in patients with glycine substitutions. Conclusion We identified pathogenic mutations in 81% of our Japanese patients with OI. Most mutations were located on COL1A1 and COL1A2. This study revealed that glycine substitutions on COL1A1 resulted in the severe phenotype among Japanese patients with OI.

Genetic analysis in Japanese patients with osteogenesis imperfecta: Genotype and phenotype spectra in 96 probands

“…Therefore, the detection rate may be affected by the ethnicity and consanguinity of the study population, and the disease severity (Fernandes et al, 2020;Mrosk et al, 2018). Ohata et al, (2019) have conducted comprehensive genetic analyses through targeted next-generation sequencing in 53 Japanese OI patients but only detected variants in COL1A1, COL1A2, and IFITM5.…”

“…Therefore, the detection rate may be affected by the ethnicity and consanguinity of the study population, and the disease severity (Fernandes et al, 2020; Mrosk et al, 2018). Ohata et al, (2019) have conducted comprehensive genetic analyses through targeted next‐generation sequencing in 53 Japanese OI patients but only detected variants in COL1A1 , COL1A2 , and IFITM5 . In fact, autosomal recessive diseases are very rare in Japan (e.g., phenylketonuria has a rate of 1:125,000, and cystic fibrosis a rate of 1:350,000), so recessive OI patients are scarcely reported (Aoki & Wada, 1988; Takeyari et al, 2018; Yamashiro et al, 1997).…”

“…OI is mainly caused by variants in type I collagen; however, the genetic analysis of OI is laborious and time‐consuming because type I collagen genes are large ( COL1A1 and COL1A2 have 51 and 52 exons within 18 and 38 kb, respectively) and have no apparent variant hotspots. Limited published data are available on the molecular diagnosis of OI in Japan (Kanno et al, 2018; Ohata et al, 2019). We previously reported six COL1A1 and three COL1A2 variants in 22 families with OI through Sanger sequencing and heteroduplex screening using denaturing high‐performance liquid chromatography (DHPLC) (Kataoka et al, 2007).…”

Understanding Musculoskeletal Disorders Through Next-Generation Sequencing

“…Novel candidate genes such as SERPINF1 101,102 , IFITM5, WNT1 103 , SEC24D, and P4HB 104 were identified by performing WES or targeted sequencing 105-109 . Several studies investigating patients with OI type V have identified mutations in the IFITM5 gene 110 . Rauch et al performed Sanger sequencing in patients with OI type V and detected a c.−14C>T mutation in IFITM5 in all of the patients, thus indicating a strong association of IFITM5 with OI type V 109 .…”

4-Phenylbutyric acid enhances the mineralization of osteogenesis imperfecta iPSC-derived osteoblasts

“…OI is mainly caused by autosomal dominant mutations of COL1A1 or COL1A2 , encoding the α1 or α2 chain of type I collagen, respectively. Variants that reduce the synthesis of type I collagen such as nonsense mutations usually result in mild OI type I, whereas variants that alter type I collagen structure such as glycine substitution mutations usually result in severe OI type III or moderate OI type IV ( 3 , 4 , 5 ). On the other hand, variants that cause exon skipping such as splice site mutations are associated with either mild OI type I, or severe OI type III, or moderate OI type IV ( 4 , 6 ).…”