Osteogenesis imperfecta: Novel genetic variants and clinical observations from a clinical exome study of 54 Indian patients.

Osteogenesis imperfecta (OI) is a group of inherited disorders with increased bone fragility and wide genetic heterogeneity. We report the outcome of clinical exome sequencing validated by Sanger sequencing in clinically diagnosed 54 OI patients in Indian population. In 52 patients, we report 20 new variants involving both dominant and recessive OI-specific genes and correlate these with phenotypes. COL1A1 and COL1A2 gene variants were identified in 44.23%, of which 28.84% were glycine substitution abnormalities. Two novel compound heterozygous variants in the FKBP10 gene were seen in two unrelated probands. A novel heterogeneous duplication of chromosomal region chr17: 48268168-48278884 from exons 1-33 of the COL1A1 gene was found in one proband. In five probands, there were additional variants in association with OI. These were ANO5 in association with CRTAP in two probands of the same family causing gnathodiaphyseal dysplasia, COL5A2 with LEPRE1 causing Ehlers Danlos syndrome, COL11A1 in addition to COL1A1 causing Stickler syndrome, and a previously unreported combination of SLC34A1 gene variant with FKBP10 leading to Fanconi renal tubular syndrome type II. Our findings demonstrate the efficacy of clinical exome sequencing in screening OI patients, classifying its subtypes, and identifying associated disorders in consanguineous populations.

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.

Pseudo-Protrusio Acetabular Deformity in Osteogenesis Imperfecta Patients.

BACKGROUND: Osteogenesis imperfecta (OI) can develop a protrusio acetabuli deformity. However, the authors observed a pseudo-protrusio-type acetabular deformity (PPAD) on 3-dimensional computed tomography (3D-CT). Hence, we systematically reviewed 3D-CT and pelvis radiographs of OI patients and report the incidence and patterns of acetabular deformity in OI patients and the associated radiographic signs. METHODS: The study included 590 hips of 295 OI patients, who were older than 5 years, and did not have a pelvic fracture. The incidence of a deformed acetabulum (center-edge angle >40 degrees) and its correlation with disease severity were investigated. In 40 hips for which 3D-CT was available, 3-dimensional morphology of the acetabular deformity was analyzed to delineate PPAD. On plain radiographs, PPAD-related signs were determined, focusing on the contour of ilioischial line, iliopectineal line, acetabular line, and their relationship. These radiographic signs were also evaluated in the remaining hips with deformed acetabula that did not have 3D-CT. RESULTS: One hundred twenty-three hips of 590 hips (21%) showed deformed acetabula. The incidence of deformed acetabula was significantly associated with disease severity (P<0.001). Three-dimensional analysis showed that 10 hips had protrusio acetabuli, whereas 17 had PPAD, which showed that the hemipelvis was crumpled, the acetabular roof was rotated upwardly and medially, and the hip center migrated superiorly, uncovering the anterior femoral head. Among the PPAD-related signs, superomedial bulging of the iliopectineal line was the most predictive radiographic sign (73% sensitivity and 100% specificity). This sign was also observed in almost one third of deformed acetabula of those investigated only with plain radiographs. CONCLUSIONS: This study showed that acetabular deformity is common in OI patients and is associated with disease severity. A substantial number of hips showed PPAD, which may not cause femoroacetabular impingement but result in anterior uncovering of the hip joint. Superomedial bulging of the iliopectineal line suggests this pattern of acetabular deformity. LEVEL OF EVIDENCE: Lever IV-prognostic studies.

COL1-related overlap disorder: A novel connective tissue disorder incorporating the osteogenesis imperfecta/Ehlers-Danlos syndrome overlap.

The 2017 classification of Ehlers-Danlos syndromes (EDS) identifies three types associated with causative variants in COL1A1/COL1A2 and distinct from osteogenesis imperfecta (OI). Previously, patients have been described with variable features of both disorders, and causative variants in COL1A1/COL1A2; but this phenotype has not been included in the current classification. Here, we expand and re-define this OI/EDS overlap as a missing EDS type. Twenty-one individuals from 13 families were reported, in whom COL1A1/COL1A2 variants were found after a suspicion of EDS. None of them could be classified as affected by OI or by any of the three recognized EDS variants associated with COL1A1/COL1A2. This phenotype is dominated by EDS-related features. OI-related features were limited to mildly reduced bone mass, occasional fractures and short stature. Eight COL1A1/COL1A2 variants were novel and five recurrent with a predominance of glycine substitutions affecting residues within the procollagen N-proteinase cleavage site of α1(I) and α2(I) procollagens. Selected variants were investigated by biochemical, ultrastructural and immunofluorescence studies. The pattern of observed changes in the dermis and in vitro for selected variants was more typical of EDS rather than OI. Our findings indicate the existence of a wider recognizable spectrum associated with COL1A1/COL1A2.

Functional Outcome of Humeral Rodding in Children With Osteogenesis Imperfecta.

BACKGROUND: The impact of humeral rodding on functional ability in children with osteogenesis imperfecta (OI) has not previously been reported. This article investigates this issue. METHODS: A retrospective chart review was conducted on 35 children with OI who underwent humeral rodding at our institution between 1995 and 2013. Fassier-Duval rods were inserted in 19 cases, K-wires in 13 cases, and Rush rods in 3 cases. Functional ability was assessed preoperatively and every year postoperatively using the self-care and mobility domains of the Pediatric Evaluation of Disability Inventory (PEDI). RESULTS: The mean PEDI self-care score increased by 5.7 (P=0.028) and the mean PEDI mobility score increased by 3.6 (P=0.008) at 1-year postsurgery. Improved function was maintained in the majority of cases at a mean of 7.0 years postcorrection. CONCLUSIONS: Humeral rodding in children with OI leads to significant improvement in functional ability. LEVEL OF EVIDENCE: Level IV.

Developmental charts for children with osteogenesis imperfecta, type I (body height, body weight and BMI).

Osteogenesis imperfecta (OI) is a rare genetic disorder of type I collagen. Type I is the most common, which is called a non-deforming type of OI, as in this condition, there are no major bone deformities. This type is characterised by blue sclera and vertebral fractures, leading to mild scoliosis. The body height of these patients is regarded as normal, or only slightly reduced, but there are no data proving this in the literature. The aim of this study is the preparation of the developmental charts of children with OI type I. The anthropometric data of 117 patients with osteogenesis imperfecta were used in this study (61 boys and 56 girls). All measurements were pooled together into one database (823 measurements in total). To overcome the problem of the limited number of data being available in certain age classes and gender groups, the method called reverse transformation was used. The body height of the youngest children, aged 2 and 3 years, is less than that of their healthy peers. Children between 4 and 7 years old catch up slightly, but at later ages, development slows down, and in adults, the median body height shows an SDS of -2.7. CONCLUSION: These results show that children with type I OI are smaller from the beginning than their healthy counterparts, their development slows down from 8 years old, and, ultimately, their body height is impaired. What is Known: • The body height of patients with osteogenesis imperfecta type I is regarded as normal, or only slightly reduced, but in the known literature, there is no measurement data supporting this opinion. What is New: • Children with type I osteogenesis imperfecta are smaller from the beginning than their healthy counterparts, their development slows down from 8 years old and, ultimately, their final body height is impaired. • The developmental charts for the body height, body weight and BMI of children with type I osteogenesis imperfecta are shown.

Advances in the Classification and Treatment of Osteogenesis Imperfecta.

Osteogenesis imperfecta (OI) is a rare disorder of type 1 collagen with 13 currently identified types attributable to inherited abnormalities in type 1 collagen amount, structure, or processing. The disease is characterized by an increased susceptibility to bony fracture. In addition to the skeletal phenotype, common additional extraskeletal manifestations include blue sclerae, dentinogenesis imperfecta, vascular fragility, and hearing loss. Medical management is focused on minimizing the morbidity of fractures, pain, and bone deformities by maximizing bone health. Along with optimizing Vitamin D status and calcium intake and physical/occupational therapy, individualized surgical treatment may be indicated. Pharmacological therapy with bisphosphonate medications is now routinely utilized for moderate to severe forms and appears to have a good safety profile and bone health benefits. New therapies with other anti-resorptives as well as anabolic agents and transforming growth factor (TGF)ß antibodies are in development. Other potential treatment modalities could include gene therapy or mesenchymal cell transplant. In the future, treatment choices will be further individualized in order to reduce disease morbidity and mortality.

Acetabular Protrusio and Proximal Femur Fractures in Patients With Osteogenesis Imperfecta.

BACKGROUND: Osteogenesis imperfect (OI) is a genetic disorder characterized by increased bone fragility, frequent fractures, and extremity deformities among other clinical findings. A frequent radiographic finding in OI patients is acetabular protrusio (AP). We hypothesized that AP incidence would be significant in OI patients and highest among type III OI patients, who have a more severe disease phenotype. In addition, we hypothesized that there would be a correlation between AP and proximal femur fracture incidence. METHODS: We retrospectively reviewed radiographs and medical records of 49 patients with OI evaluated at our institution. Demographic information and modified Sillence classification were recorded. AP was diagnosed using previously published radiographic criteria using the center-edge angle of Wiberg, acetabulum relative to the iliopectineal line, teardrop figure relative to the ilioischial (Kohler) line, and acetabulum relative to the ilioischial (Kohler) line. Medical record and radiographs were reviewed for evidence of proximal femur or acetabulum fracture. Associations between OI type, AP, and fracture incidence were examined with χ or Fisher exact tests. RESULTS: In this series of 49 OI patients, the overall incidence of AP was 55.1% (27/49) with the highest incidence among patients with type III OI (70.6%). There was an increased incidence of proximal femur, and particularly femoral neck, fractures among patients with AP compared with patients with normal hip anatomy. Overall, patients with AP had a 30% increased risk for proximal femur and acetabulum fractures (P=0.03). CONCLUSIONS: AP is a common deformity in OI patients (55.1%) and particularly type III OI (70.6%). Patients with AP have an increased risk for proximal femur fractures and particularly femoral neck fractures. This novel finding adds to the growing body of literature on clinical implications of AP in OI patients. LEVEL OF EVIDENCE: Level IV-Retrospective case series.

Classification of osteogenesis imperfecta.

Osteogenesis imperfecta (OI) is an extremely heterogeneous group of heritable connective tissue disorders. Most of the affected patients carry autosomal dominant mutations in the genes encoding for collagen type I, the most abundant protein of the bone extracellular matrix. The resulting phenotypes are extremely broad and have been classified by Sillence and colleagues into four groups according to clinical, radiological and genetic criteria.More recently, proteins have been described that interact directly or indirectly with collagen biosynthesis and their deficiency result in rare forms of mostly autosomal recessive OI sharing phenotypic features of 'classical' types but lacking primary defects in type I collagen. Consequently the Sillence classification has been gradually expanded to include novel forms based on the underlying mutations. The goal of this article is to revisit the actual OI classification and to outline current approaches in categorizing the disorder.

Osteogenesis imperfecta: clinical diagnosis, nomenclature and severity assessment.

Recently, the genetic heterogeneity in osteogenesis imperfecta (OI), proposed in 1979 by Sillence et al., has been confirmed with molecular genetic studies. At present, 17 genetic causes of OI and closely related disorders have been identified and it is expected that more will follow. Unlike most reviews that have been published in the last decade on the genetic causes and biochemical processes leading to OI, this review focuses on the clinical classification of OI and elaborates on the newly proposed OI classification from 2010, which returned to a descriptive and numerical grouping of five OI syndromic groups. The new OI nomenclature and the pre-and postnatal severity assessment introduced in this review, emphasize the importance of phenotyping in order to diagnose, classify, and assess severity of OI. This will provide patients and their families with insight into the probable course of the disorder and it will allow physicians to evaluate the effect of therapy. A careful clinical description in combination with knowledge of the specific molecular genetic cause is the starting point for development and assessment of therapy in patients with heritable disorders including OI. © 2014 The Authors. American Journal of Medical Genetics Published by Wiley Periodicals, Inc. This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made.

Impact of three genetic musculoskeletal diseases: a comparative synthesis of achondroplasia, Duchenne muscular dystrophy and osteogenesis imperfecta.

Achondroplasia, Duchenne muscular dystrophy, and osteogenesis imperfecta are among the most frequent rare genetic disorders affecting the musculoskeletal system in children. Rare genetic disorders are severely disabling and can have substantial impacts on families, children, and on healthcare systems. This literature review aims to classify, summarize and compare these non-medical impacts of achondroplasia, Duchenne muscular dystrophy and osteogenesis imperfecta.

Osteogenesis imperfecta types I-XI: implications for the neonatal nurse.

Osteogenesis imperfecta (OI), also called "brittle bone disease," is a rare heterozygous connective tissue disorder that is caused by mutations of genes that affect collagen. Osteogenesis imperfecta is characterized by decreased bone mass, bone fragility, and skin hyperlaxity. The phenotype present is determined according to the mutation on the affected gene as well as the type and location of the mutation. Osteogenesis imperfecta is neither preventable nor treatable. Osteogenesis imperfecta is classified into 11 types to date, on the basis of their clinical symptoms and genetic components. This article discusses the definition of the disease, the classifications on the basis of its clinical features, incidence, etiology, and pathogenesis. In addition, phenotype, natural history, diagnosis and management of this disease, recurrence risk, and, most importantly, the implications for the neonatal nurse and management for the family are discussed.

Letter to the editor: Re: Pathogenic mechanisms of osteogenesis imperfecta, evidence for classification.

A paper published in Orphanet Journal of Rare Diseases proposes a new classification of osteogenesis imperfecta (OI) based upon underlying pathological mechanisms. The proposed numbering of OI types conflicts with the currently used numbering and is likely to lead to confusion. In addition, classification of OI according to underlying pathogenic mechanisms is not novel.

Osteogenesis imperfecta type V: clinical and radiographic manifestations in mutation confirmed patients.

Osteogenesis imperfecta (OI) type V is a specific OI phenotype with interosseous membrane calcification of the forearm and hyperplastic callus formation as typical features. The causative gene mutation for OI type V has been recently discovered. The purpose of this report is to review the clinical and radiographic characteristics of mutation confirmed OI type V in detail. Sixteen (nine familial and seven sporadic) patients were enrolled in the study. Blue sclera and dentinogenesis imperfecta were not evident in any patient. However, hypodontia in the permanent teeth, ectopic eruption, and short roots in molars were additionally observed in 11 patients. Of the radiographic abnormalities, cortical thickening and bony excrescence of interosseous margin of the ulna was the most common finding, followed by overgrowth of the olecranon and/or coronoid process of the ulna. Slender ribs and sloping of the posterior ribs with or without fractures were also a consistent finding. Hyperplastic callus was detected in 75% of patients and was commonly encountered at the femur. Heterotopic ossification in the muscles and tendon insertion sites were noted in four patients, which resulted in bony ankylosis or contracture of joints. The current study confirms common clinical and radiographic findings of OI type V and reports additional phenotypic information. These observations provide clues to recognize OI type V more promptly and guide to direct targeted molecular study. © 2013 Wiley Periodicals, Inc.

Osteogenesis imperfecta.

Osteogenesis imperfecta (OI), an inherited skeletal disorder characterized by low bone mass, bone fragility, and often short stature. The clinical severity varies widely from being nearly asymptomatic with a mild predisposition to fractures, normal stature and normal lifespan being to profoundly disabling and even lethal. Extra skeletal manifestations may include blue-grey sclera and dental abnormalities. Initially, the classification of OI into four types was based on clinical findings, but more recently additional types OI (types V-XI) have been ascertained, based on the identification of different mutations. While this classification is somewhat controversial, it is described in this article. The treatment of patients with OI is based on the nature and severity of symptoms. The goal of therapy is to prevent fractures and disability, improve function and quality of life. A multidisciplinary approach is needed, and treatment options include medication such as bisphosphonates, surgery, and rehabilitation. Investigations continue to explore gene and cell therapies that may be developed in the future.

Osteogenesis imperfecta/lobstein syndrome associated with dentinogenesis imperfecta.

Osteogenesis imperfecta is a collagen related disorder characterized by increased bone fragility and low bone mass. The important oral finding in osteogenesis imperfect is the presence of dentinogenesis imperfecta. This article presents a case of osteogenesis imperfecta (type IV B) with dentinogenesis imperfecta where a 7-year-old girl had opalacent primary teeth associated with severe bone deformity, scoliosis, barrel shaped rib cage, and short stature. The clinical, radiographic ad histologic features are reviewed along with management aspects.

[Clinical condition and therapy of bone diseases].

Skeletal dysplasia is the term which represents disorders including growth and differentiation of bone, cartilage and ligament. A lot of diseases are included, and new disorders have been added. However, the therapy of most bone diseases is less well-established. Achondroplasia, hypochondroplasia, and osteogenesis imperfecta are most frequent bone diseases. There is no curative treatment for these diseases, however, supportive therapies are available ; for example, growth-hormone therapy for achondroplasia and hypochondroplasia, and bisphosphonate therapy for osteogenesis imperfecta. In addition, enzyme replacement therapy for hypophosphatasia is now on clinical trial.

Osteogensis imperfecta and role of nurse in management.

Osteogenesis imperfecta (OI) is a rare but striking cause of bone fragility and fractures. It usually presents in children or young adults. Consider it in the differential diagnosis when a child presents with a history of recurrent fractures. Early detection can improve morbidity. Nurses, if have the knowledge of the disease, can protect the child in hospital and can educate parents appropriately how to take care the child.

Absence of FKBP10 in recessive type XI osteogenesis imperfecta leads to diminished collagen cross-linking and reduced collagen deposition in extracellular matrix.

Recessive osteogenesis imperfecta (OI) is caused by defects in genes whose products interact with type I collagen for modification and/or folding. We identified a Palestinian pedigree with moderate and lethal forms of recessive OI caused by mutations in FKBP10 or PPIB, which encode endoplasmic reticulum resident chaperone/isomerases FKBP65 and CyPB, respectively. In one pedigree branch, both parents carry a deletion in PPIB (c.563_566delACAG), causing lethal type IX OI in their two children. In another branch, a child with moderate type XI OI has a homozygous FKBP10 mutation (c.1271_1272delCCinsA). Proband FKBP10 transcripts are 4% of control and FKBP65 protein is absent from proband cells. Proband collagen electrophoresis reveals slight band broadening, compatible with ≈10% over-modification. Normal chain incorporation, helix folding, and collagen T(m) support a minimal general collagen chaperone role for FKBP65. However, there is a dramatic decrease in collagen deposited in culture despite normal collagen secretion. Mass spectrometry reveals absence of hydroxylation of the collagen telopeptide lysine involved in cross-linking, suggesting that FKBP65 is required for lysyl hydroxylase activity or access to type I collagen telopeptide lysines, perhaps through its function as a peptidylprolyl isomerase. Proband collagen to organics ratio in matrix is approximately 30% of normal in Raman spectra. Immunofluorescence shows sparse, disorganized collagen fibrils in proband matrix.

Recessive osteogenesis imperfecta: clinical, radiological, and molecular findings.

Osteogenesis imperfecta (OI) or "brittle bone disease" is currently best described as a group of hereditary connective tissue disorders related to primary defects in type I procollagen, and to alterations in type I procollagen biosynthesis, both associated with osteoporosis and increased susceptibility to bone fractures. Initially, the autosomal dominant forms of OI, caused by mutations in either COL1A1 or COL1A2, were described. However, for decades, the molecular defect of a small percentage of patients clinically diagnosed with OI has remained elusive. It has been in the last 6 years that the genetic causes of several forms of OI with autosomal recessive inheritance have been characterized. These comprise defects of collagen chaperones, and proteins involved in type I procollagen assembly, processing and maturation, as well as proteins involved in the formation and homeostasis of bone tissue. This article reviews the recently characterized forms of recessive OI, focusing in particular on their clinical and molecular findings, and on their radiological characterisation. Clinical management and treatment of OI in general will be discussed, too.