Genotype-phenotype correlation among Malaysian patients with osteogenesis imperfecta

Dental Abnormalities in Osteogenesis Imperfecta: A Systematic Review

Osteogenesis imperfecta (OI) is a rare genetic disorder characterized by fragile bones and skeletal deformities. Individuals with OI may have dental abnormalities such as dentinogenesis imperfecta (DI) type I, malocclusions, and unerupted or missing teeth. This review comprehensively examines these dental abnormalities to assess their prevalence among the OI population and explore potential differences across different clinical types of OI and pathogenic variants. In accordance with the PRISMA guidelines, a systematic literature search in PubMed, Embase, and Web of Science was conducted that included articles up to June 2024. Out of 672 articles screened, 34 were included. The included studies confirmed that dental abnormalities are prevalent in OI, with DI prevalence ranging from approximately 20 to 48%. Those with a more severe skeletal phenotype (OI type III/IV) exhibited more dental abnormalities than those with a milder skeletal phenotype (OI type I). Notably, OI type V individuals generally do not have DI, although a few isolated cases have been reported. The prevalence of occlusion types varied: Class I occlusion ranged from 14.8 to 50% and Class II malocclusion ranged from 0 to 37.5%, while Class III malocclusion from 4.1 to 84%. This differs from the general population, where Class III malocclusion is typically the least common. Open bites, cross-bites, and unerupted and missing teeth are also commonly reported, particularly in OI types III and IV. This review emphasizes the need for comprehensive dental examinations in OI due to the high prevalence of dental abnormalities. Additionally, the review draws attention to the lack of clear guidelines for diagnosing DI.

Genotype and Phenotype Correlation of Patients with Osteogenesis Imperfecta

Osteogenesis imperfecta (OI) is the most common inherited connective tissue disease of the bone, characterized by recurrent fractures and deformities. In patients displaying the OI phenotype, genotype-phenotype correlation is used to screen multiple genes swiftly, identify new variants, and distinguish between differential diagnoses and mild subtypes. This study evaluated variants identified through next-generation sequencing in 58 patients with clinical characteristics indicative of OI. The cohort included 18 adults, 37 children, and 3 fetuses. Clinical classification revealed 25 patients as OI type I, three patients as OI type II, 18 as OI type III, and 10 as OI type IV. Fifteen variants in COL1A1 were detected in 19 patients, 9 variants in COL1A2 (n = 19), 5 variants in LEPRE1/P3H1 (n = 7), 3 variants in FKBP10 (n = 4), 3 variants in SERPINH1 (n = 2), 1 variant in IFITM5 (n = 1), and 1 variant in PLS3 (n = 1). In total, 37 variants (18 pathogenic, 14 likely pathogenic, and 5 variants of uncertain significance), including 16 novel variants, were identified in 43 (37 probands, 6 family members) of the 58 patients analyzed. This study highlights the efficacy of panel testing in the molecular diagnosis of OI, the significance of the next-generation sequencing technique, and the importance of genotype-phenotype correlation.

Prevalence of Monogenic Bone Disorders in a Dutch Cohort of Atypical Femur Fracture Patients

Atypical femur fractures (AFFs), considered rare associations of bisphosphonates, have also been reported in patients with monogenic bone disorders without bisphosphonate use. The exact association between AFFs and monogenic bone disorders remains unknown. Our aim was to determine the prevalence of monogenic bone disorders in a Dutch AFF cohort. AFF patients were recruited from two specialist bone centers in the Netherlands. Medical records of the AFF patients were reviewed for clinical features of monogenic bone disorders. Genetic variants identified by whole-exome sequencing in 37 candidate genes involved in monogenic bone disorders were classified based on the American College of Medical Genetics and Genomics (ACMG) classification guidelines. Copy number variations overlapping the candidate genes were also evaluated using DNA array genotyping data. The cohort comprises 60 AFF patients (including a pair of siblings), with 95% having received bisphosphonates. Fifteen AFF patients (25%) had clinical features of monogenic bone disorders. Eight of them (54%), including the pair of siblings, had a (likely) pathogenic variant in either PLS3, COL1A2, LRP5, or ALPL. One patient carried a likely pathogenic variant in TCIRG1 among patients not suspected of monogenic bone disorders (2%). In total, nine patients in this AFF cohort (15%) had a (likely) pathogenic variant. In one patient, we identified a 12.7 Mb deletion in chromosome 6, encompassing TENT5A. The findings indicate a strong relationship between AFFs and monogenic bone disorders, particularly osteogenesis imperfecta and hypophosphatasia, but mainly in individuals with symptoms of these disorders. The high yield of (likely) pathogenic variants in AFF patients with a clinical suspicion of these disorders stresses the importance of careful clinical evaluation of AFF patients. Although the relevance of bisphosphonate use in this relationship is currently unclear, clinicians should consider these findings in medical management of these patients. © 2023 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).

Does the c.-14C>T Mutation in the IFITM5 Gene Provide Identical Phenotypes for Osteogenesis Imperfecta Type V? Data from Russia and a Literature Review

Osteogenesis imperfecta (OI) is a large group of genetically heterogeneous diseases resulting from decreased bone density and an abnormal microarchitecture, which are clinically manifested by abnormal bone fractures. A distinctive clinical feature of this group of diseases is the presence of spontaneous fractures and skeletal deformities. However, the clinical manifestations of different types of OI are characterized by marked polymorphism with variable severity of skeletal and extra-skeletal features. Previous studies have shown that a mutation (c.-14C>T) in the IFITM5 gene is responsible for autosomal dominant OI type V. However, the mutation has a variable expression pattern and marked clinical heterogeneity. In this study, a clinical and genetic analysis of 12 cases with molecularly confirmed OI type V from 12 unrelated families was performed. Significant clinical heterogeneity of the disease with the same molecular defect was detected. In six subjects (50%), there were no classic signs of OI type V (formation of a hyperplastic bone callus, calcification of the interosseous membrane and dislocation of the radial head). In all cases, the mutation occurred de novo.

A single-centre study of genetic mutations, audiology, echocardiogram and pulmonary function in Saudi children with osteogenesis imperfecta

OBJECTIVES

Osteogenesis imperfecta (OI) is a heterogeneous group of inherited connective tissue disorders, characterised by skeletal fragility. Patients with OI may also exhibit extra-skeletal features like blue or grey scleral colour, fragile skin, easy bruising, joint laxity, short stature, deafness, cardiac valve abnormalities and abnormal pulmonary function. The objective of this study is to describe genetic mutations, prevalence of hearing issues, cardiac complications and impaired pulmonary function in children with OI.

METHODS

This is a cross-sectional study of 23 Saudi children aged 6 months to 18 years who were diagnosed with OI. The revised Sillence classification (2,105) was used to classify the OI type. Whole exome sequencing was performed for genetic mutations. The hearing was assessed by either pure-tone audiometry and/or otoacoustic emission testing. Cardiac defects were screened by echocardiograms. Spirometry was performed to assess pulmonary function. Data were analysed with descriptive statistics.

RESULTS

Based on the Sillence classification, 16 patients had OI type III, 6 had type IV and 1 had type I. Of the18 patients who had genetic sequencing, 66.6% had autosomal dominant and 33.3% had autosomal recessive mutations. Among children who had screening, hearing loss was diagnosed in 53% (9/17), congenital cardiac malformations in 26% (5/19) and restrictive lung disease in 70% (7/10).

CONCLUSIONS

We found significant extra-skeletal features and a high yield of genetic mutations associated with OI. We suggest further studies to develop a screening protocol for extra-skeletal features in children with OI.

Osteogenesis Imperfecta: Search for Mutations in Patients from the Republic of Bashkortostan (Russia)

Osteogenesis imperfecta (OI) is an inherited disease of bone characterized by increased bone fragility. Here, we report the results of the molecular architecture of osteogenesis imperfecta research in patients from Bashkortostan Republic, Russia. In total, 16 mutations in COL1A1, 11 mutations in COL1A2, and 1 mutation in P3H1 and IFIMT5 genes were found in isolated states; 11 of them were not previously reported in literature. We found mutations in CLCN7, ALOX12B, PLEKHM1, ERCC4, ARSB, PTH1R, and TGFB1 that were not associated with OI pathogenesis in patients with increased bone fragility. Additionally, we found combined mutations (c.2869C>T, p. Gln957* in COL1A1 and c.1197+5G>A in COL1A2; c.579delT, p. Gly194fs in COL1A1 and c.1197+5G>A in COL1A2; c.2971G>C, p. Gly991Arg in COL1A2 and c.212G>C, p.Ser71Thr in FGF23; c.-14C>T in IFITM5 and c.1903C>T, p. Arg635* in LAMB3) in 4 patients with typical OI clinic phenotypes.

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

BACKGROUND

Osteogenesis imperfecta (OI) is a rare connective-tissue disorder characterized by bone fragility. Approximately 90% of all OI cases are caused by variants in COL1A1 or COL1A2. Additionally, IFITM5 variants are responsible for the unique OI type 5. We previously analyzed COL1A1/2 variants in 22 Japanese families with OI through denaturing high-performance liquid chromatography screening, but our detection rate was low (41%).

METHODS

To expand the genotype-phenotype correlations, we performed a genetic analysis of COL1A1/2 and IFITM5 in 96 non-consanguineous Japanese OI probands by Sanger sequencing.

RESULTS

Of these individuals, 54, 41, and 1 had type 1 (mild), type 2-4 (moderate-to-severe), and type 5 phenotypes, respectively. In the mild group, COL1A1 nonsense and splice-site variants were prevalent (n = 30 and 20, respectively), but there were also COL1A1 and COL1A2 triple-helical glycine substitutions (n = 2 and 1, respectively). In the moderate-to-severe group, although COL1A1 and COL1A2 glycine substitutions were common (n = 14 and 18, respectively), other variants were also detected. The single case of type 5 had the characteristic c.-14C>T variant in IFITM5.

CONCLUSION

These results increase our previous detection rate for COL1A1/2 variants to 99% and provide insight into the genotype-phenotype correlations in OI.

The evolution of the nosology of osteogenesis imperfecta

Osteogenesis imperfecta (OI) is a relatively common genetic skeletal disorder with an estimated frequency of 1 in 20 000 worldwide. The manifestations are diverse and although individually rare, the several different forms contribute to the production of a significant number of affected individuals with considerable morbidity and mortality. During the last decade, there have been extensive molecular investigations into the etiology of OI and these advances have direct relevance to the medical management of the disorder, and the purpose of this review is to document the history and evolution of the nosology of OI. The current nosology, based on molecular concepts, which are crucial in the identification of genotype-phenotype correlations in persons with OI, is also outlined. The successive revisions of the nosology and classification of OI have highlighted the importance of the nomenclature of the condition in order for it to be recognized by clinicians, scientists and patient advocacy groups. In this way, improved counseling of patients and individualized, tailored therapeutic approaches based on the underlying pathophysiology of the individual's type of OI have been facilitated.

The molecular landscape of osteogenesis imperfecta in a Brazilian tertiary service cohort

We have sought the molecular diagnosis of OI in 38 Brazilian cases through targeted sequencing of 15 candidate genes. While 71% had type 1 collagen-related OI, defects in FKBP10, PLOD2 and SERPINF1, and a potential digenic P3H1/WNT1 interaction were prominent causes of OI in this underrepresented population.

INTRODUCTION

Defects in type 1 collagen reportedly account for 85-90% of osteogenesis imperfecta (OI) cases, but most available molecular data has derived from Sanger sequencing-based approaches in developed countries. Massively parallel sequencing (MPS) allows for systematic and comprehensive analysis of OI genes simultaneously. Our objective was to obtain the molecular diagnosis of OI in a single Brazilian tertiary center cohort.

METHODS

Forty-nine individuals (84% adults) with a clinical diagnosis of OI, corresponding to 30 sporadic and 8 familial cases, were studied. Sixty-three percent had moderate to severe OI, and consanguinity was common (26%). Coding regions and 25-bp boundaries of 15 OI genes (COL1A1, COL1A2, IFITM5 [plus 5'UTR], SERPINF1, CRTAP, P3H1, PPIB, SERPINH1, FKBP10, PLOD2, BMP1, SP7, TMEM38B, WNT1, CREB3L1) were analyzed by targeted MPS and variants of interest were confirmed by Sanger sequencing or SNP array.

RESULTS

A molecular diagnosis was obtained in 97% of cases. COL1A1/COL1A2 variants were identified in 71%, whereas 26% had variants in other genes, predominantly FKBP10, PLOD2, and SERPINF1. A potential digenic interaction involving P3H1 and WNT1 was identified in one case. Phenotypic variability with collagen defects could not be explained by evident modifying variants. Four consanguineous cases were associated to heterozygous COL1A1/COL1A2 variants, and two nonconsanguineous cases had compound PLOD2 heterozygosity.

CONCLUSIONS

Novel disease-causing variants were identified in 29%, and a higher proportion of non-collagen defects was seen. Obtaining a precise diagnosis of OI in underrepresented populations allows expanding our understanding of its molecular landscape, potentially leading to improved personalized care in the future.