Diagnosis Of Osteogenesis Imperfecta Research Articles

Exome Sequencing for the Diagnostics of Osteogenesis Imperfecta in Six Russian Patients.

Osteogenesis imperfecta (OI) is a group of inherited disorders of connective tissue that cause significant deformities and fragility in bones. Most cases of OI are associated with pathogenic variants in collagen type I genes and are characterized by pronounced polymorphisms in clinical manifestations and the absence of clear phenotype-genotype correlation. The objective of this study was to conduct a comprehensive molecular-genetic and clinical analysis to verify the diagnosis of OI in six Russian patients with genetic variants in the COL1A1 and COL1A2 genes. Clinical and laboratory data were obtained from six OI patients who were observed at the Medical Genetics Center in Saint Petersburg from 2016 to 2023. Next-generation sequencing on MGISEQ G400 (MGI, China) was used for DNA analysis. The GATK bioinformatic software (version 4.5.0.0) was used for variant calling and hard filtering. Genetic variants were verified by the direct automatic sequencing of PCR products using the ABI 3500X sequencer. We identified six genetic variants, as follows pathogenic c.3505G>A (p. Gly1169Ser), c.769G>A (p.Gly257Arg), VUS c.4123G>A (p.Ala1375Thr), and c.4114A>T (p.Asn1372Tyr) in COL1A1; and likely pathogenic c.2035G>A (p.Gly679Ser) and c.739-2A>T in COL1A2. In addition, clinical cases are presented due to the presence of the c.4114A>T variant in the COL1A2 gene. Molecular genetics is essential for determining different OI types due to the high similarity across various types of the disease and the failure of unambiguous diagnosis based on clinical manifestations alone. Considering the variable approaches to OI classification, an integrated strategy is required for optimal patient management.

‘BLUES’ procedure for assessing the blue level of the sclera in Osteogenesis Imperfecta

PurposeBlue sclera is a characteristic and common clinical sign of Osteogenesis Imperfecta (OI). However, there is currently no widely accepted, objective method for assessing and grading blue sclera in individuals with OI.To address this medical need, this study is aimed to design and validate a new method called ‘BLUES’ (BLUe Eye Sclera) to objectively identify and quantify the blue color in the sclera of patients affected by OI.MethodsSixty-two patients affected by OI and 35 healthy controls were enrolled in the present prospective study, for a total of 194 eyes analyzed.In the 'BLUES' procedure, eye images from patients with OI and control subjects were analyzed to assess and grade the blue level of the sclera using Adobe Photoshop Software. The validation process then involved comparing the results obtained with the ‘BLUES’ procedure to the judgement of experienced ophthalmologists (JEO).A receiver-operating characteristic (ROC) curve analysis was used to examine the overall discriminatory power. The sensitivity and specificity levels and the Cohen's Kappa (K) indexes of ‘BLUES’ and ‘JEO’ were estimated versus the standard OI diagnosis. The K indexes of ‘BLUES’ versus ‘JEO’ were also evaluated.ResultsThe optimal cut-off point of the scleral blue peak was calculated at 17%. Our findings demonstrated a sensitivity of 89% (CI95%: 0.835–0.945) and specificity of 87% (CI95%: 0.791–0.949) for the ‘BLUES’ procedure with an agreement versus the diagnosis of OI of 0.747. In comparison, the sensitivity and specificity of ‘JEO’ ranged from 89 to 94% and 77% to 100%, respectively, with an agreement ranging from 0.663 to 0.871 with the diagnosis of OI. The agreement between ‘BLUES ‘and ‘JEO’ evaluations ranged from 0.613 to 0.734.ConclusionsOur findings demonstrated an 89% sensitivity and an impressive 87% specificity of our method to analyze the blue sclera in OI. The results indicated high agreement with disease diagnosis and were consistent with evaluations by experienced ophthalmologists. The ‘BLUES’ procedure appears to be a simple, reliable and objective method for effectively identify and quantify the blue color of the sclera in OI.

Imaging in osteogenesis imperfecta: Where we are and where we are going

Osteogenesis imperfecta (OI) is a rare phenotypically and genetically heterogeneous group of inherited skeletal dysplasias. The hallmark features of OI include bone fragility and susceptibility to fractures, bone deformity, and diminished growth, along with a plethora of associated secondary features (both skeletal and extraskeletal). The diagnosis of OI is currently made on clinical grounds and may be confirmed by genetic testing. However, imaging remains pivotal in the evaluation of this disease. The aim of this article is to review the current role played by the various radiologic techniques in the diagnosis and monitoring of OI in the postnatal setting as well as to discuss recent advances and future perspectives in OI imaging. Conventional Radiography and Dual-energy X-ray Absorptiometry (DXA) are currently the two most used imaging modalities in OI. The cardinal radiographic features of OI include generalized osteopenia/osteoporosis, bone deformities, and fractures. DXA is currently the most available technique to assess Bone Mineral Density (BMD), specifically areal BMD (aBMD). However, DXA has important limitations and cannot fully characterize bone fragility in OI based on aBMD. Novel DXA-derived parameters, such as Trabecular Bone Score (TBS), may provide further insight into skeletal changes induced by OI, but evidence is still limited. Techniques like Computed Tomography (CT) and Magnetic Resonance Imaging (MRI) can be useful as problem-solvers or in specific settings, including the evaluation of cranio-cervical abnormalities. Recent evidence supports the use of High-Resolution peripheral Quantitative Computed Tomography (HR-pQCT) as a promising tool to improve the characterization of bone fragility in OI. However, HR-pQCT remains a primarily research technique at present. Quantitative Computed Tomography (QCT) is an alternative to DXA for the determination of BMD at central sites, with distinct advantages but considerably higher radiation exposure. Quantitative Ultrasound (QUS) is a portable, inexpensive, and radiation-free modality that may complement DXA evaluation, providing information on bone quality. However, evidence of usefulness of QUS in OI is poor. Radiofrequency Echographic Multi Spectrometry (REMS) is an emerging non-ionizing imaging method that holds promise for the diagnosis of low BMD and for the prediction of fracture risk, but so far only one published study has investigated its role in OI. To conclude, several different radiologic techniques have proven to be effective in the diagnosis and monitoring of OI, each with their own specificities and peculiarities. Clinicians should be aware of the strategic role of the various modalities in the different phases of the patient care process. In this scenario, the development of international guidelines including recommendations on the role of imaging in the diagnosis and monitoring of OI, accompanied by continuous active research in the field, could significantly improve the standardization of patient care.

The experiences of the families with children diagnosed with osteogenesis imperfecta: A Qualiative study in Turkey

BackgroundThe diagnosis of osteogenesis imperfecta affects the whole lives of family members. This study aims to investigate the lived experience of families with children diagnosed with osteogenesis imperfecta. Design and methodsThis study used a qualitative, phenomenological design. The study sample consisted of parents of the children who were followed up with the diagnosis of osteogenesis imperfecta in the pediatric endocrinology clinic in Turkey. In order to collect data, a semi-structured interview form was prepared, and data were collected by way of face-to-face interviews. The lived experience of families were analyzed using qualitative methods. The life experiences of the families were analyzed in depth using qualitative methods. ResultsIn the study, six themes were identified, including having a child diagnosed with osteogenesis imperfecta, family process, life patterns, emotional dimension, social life, and economic dimension. The results revealed that parents did not know about the disease upon learning of the child's diagnosis. Parents stated that they experienced anxiety, disappointment, sadness, denial, and despair when they first learned about their children's diagnosis. They also indicated that having a child with osteogenesis imperfecta affected the whole family in physiological, psychological, and social aspects. ConclusionParents and children should be given information about the disease since the first diagnosis of osteogenesis imperfecta, and psychosocial support should be provided. Families that can not get sufficient psychosocial support experience difficulties in the medical and care management of the disease. Practice implicationsKnowing and understanding the lived experiences of families living with osteogenesis imperfecta can guide the planning and implementation of quality nursing care processes.

RNA Sequencing of Urine-Derived Cells for the Characterisation and Diagnosis of Osteogenesis Imperfecta.

DNA sequencing is a reliable tool for identifying genetic variants in osteogenesis imperfecta (OI), but cannot always establish pathogenicity, particularly in variants altering splicing. RNA sequencing can provide functional evidence of the effect of a variant on the transcript but requires cells expressing the relevant genes. Here we used urine-derived cells (UDC) to characterize genetic variants in patients with suspected or confirmed OI and provide evidence on the pathogenicity of variants of uncertain significance (VUS). Urine samples were obtained from 45 children and adolescents; UDS culture was successful in 40 of these participants (age range 4 to 20 years 21 females), including 18 participants with OI or suspected OI who had a candidate variant or VUS on DNA sequencing. RNA was extracted from UDC and sequenced on an Illumina NextSeq550 device. Principal component analysis showed that the gene expression profiles of UDC and fibroblasts (based on GTEx consortium data) clustered close together, and had less variability than those of whole blood cells. Transcript abundance was sufficient for analysis by RNA sequencing (defined as a median gene expression level of ≥ 10 transcripts per million) for 25 of the 32 bone fragility genes (78%) that were included in our diagnostic DNA sequencing panel. These results were similar to GTEx data for fibroblasts. Abnormal splicing was identified in 7 of the 8 participants with pathogenic or likely pathogenic variants in the splice region or deeper within the intron. Abnormal splicing was also observed in 2 VUS (COL1A1 c.2829+5G>A and COL1A2 c.693+6T>G), but no splice abnormality was seen in 3 other VUS. Abnormal deletions and duplications could also be observed in UDC transcripts. In conclusion, UDC are suitable for RNA transcript analysis in patients with suspected OI and can provide functional evidence for pathogenicity, in particular of variants affecting splicing. This article is protected by copyright. All rights reserved.

The prevalence of musculoskeletal pain and therapy needs in adults with Osteogenesis Imperfecta (OI) a cross-sectional analysis

BackgroundOsteogenesis Imperfecta affects approximately 1 in every 10,000 people. Musculoskeletal disorders and pain are common in adults with Osteogenesis Imperfecta, but specific knowledge of the problems people have is lacking. Access to therapy services for adults with Osteogenesis Imperfecta is variable. We designed this analysis to better understand the musculoskeletal disorders and consequent therapy needs for adults with Osteogenesis Imperfecta. MethodsThis study was a cross-sectional analysis of outpatients with Osteogenesis Imperfecta. Adults attending a newly established multidisciplinary clinic at a tertiary centre in 2019 were included. A highly specialist physiotherapist worked within the clinic to offer therapy input if required and to refer patients to appropriate therapy as needed. People over the age of 18 were included if they had a diagnosis of Osteogenesis Imperfecta. Data were collected over a five month period using routinely collected clinical information and patient reported outcomes.ResultsOver five months 50 patients attended the clinic. Musculoskeletal pain was a significant feature reported by 84% of patients. Over 50% of patients reported persistent pain for longer than one year duration and the most common site of pain was in the spine (46%). No difference in pain between types of OI and age. Forty five per cent (n = 19) of patients reported moderate to severe problems with mobility on the EQ-5D with over half reporting problems with self-care and ability to carry out usual activities. Over 50% of patients in clinic also reported anxiety (EQ-5D). During the consultation 70% of patients received therapy input which was either advice in clinic or an onward referral to the appropriate service. The referral rate to specialist out-patient rehabilitation services at a tertiary centre was 30%.ConclusionsThis analysis highlights the high prevalence of MSK pain in adults with OI and the effect on physical function and emotional wellbeing. This study demonstrates the diverse needs of the adult Osteogenesis Imperfecta population and the need for suitable multidisciplinary therapy services.

Mutational Screening of Skeletal Genes in 14 Chinese Children with Osteogenesis Imperfecta Using Targeted Sequencing.

Background As a heterogeneous hereditary connective tissue disorder, osteogenesis imperfecta (OI) is clinically characterized by increased fracture susceptibility. Analysis of genetic pathogenic variants in patients with OI provides a basis for genetic counseling and prenatal diagnosis. Methods In this study, 14 diagnosed OI patients from sporadic Chinese families were enrolled to be screened for potential mutations from these patients by next-generation sequencing technology. Results 34 different variants were identified. 18 variants were from 4 OI-related genes including COL1A1, COL1A2, P3H1, and WNT1, and 10 variants are novel. Most OI patients (11 out of 14, 78%) harbor variants in type I collagen genes. Conclusions Our results support previously established estimates of the distribution and prevalence of OI mutations and highlight both phenotype and genetic heterogeneity among and within families. We report several novel variants of OI, which expands the clinical spectrum of OI. In summary, our data provides disease-causing genes information for genetic counseling towards OI patients and families and also provides a reference for clinicians in the diagnosis of OI, also in prenatal diagnosis of this disease.

Phenotypic Variation in Vietnamese Osteogenesis Imperfecta Patients Sharing a Recessive P3H1 Pathogenic Variant.

Osteogenesis imperfecta (OI) is a syndromic disorder of bone fragility with high variation in its clinical presentation. Equally variable is molecular aetiology; recessive forms are caused by approximately 20 different genes, many of which are directly implicated in collagen type I biosynthesis. Biallelic variants in prolyl 3-hydroxylase 1 (P3H1) are known to cause severe OI by affecting the competence of the prolyl 3-hydroxylation—cartilage associated protein—peptidyl-prolyl cis-trans isomerase B (P3H1-CRTAP-CyPB) complex, which acts on the Pro986 residue of collagen type I α 1 (COL1A1) and Pro707 collagen type I α 2 (COL1A2) chains. The investigation of an OI cohort of 146 patients in Vietnam identified 14 families with P3H1 variants. The c.1170+5G>C variant was found to be very prevalent (12/14) and accounted for 10.3% of the Vietnamese OI cohort. New P3H1 variants were also identified in this population. Interestingly, the c.1170+5G>C variants were found in families with the severe clinical Sillence types 2 and 3 but also the milder types 1 and 4. This is the first time that OI type 1 is reported in patients with P3H1 variants expanding the clinical spectrum. Patients with a homozygous c.1170+5G>C variant shared severe progressively deforming OI type 3: bowed long bones, deformities of ribcage, long phalanges and hands, bluish sclera, brachycephaly, and early intrauterine fractures. Although it remains unclear if the c.1170+5G>C variant constitutes a founder mutation in the Vietnamese population, its prevalence makes it valuable for the molecular diagnosis of OI in patients of the Kinh ethnicity. Our study provides insight into the clinical and genetic variation of P3H1-related OI in the Vietnamese population.

When Is an Isolated Olecranon Fracture Pathognomonic for Osteogenesis Imperfecta?

Isolated fractures of the olecranon process of the ulna in pediatric patients with open physes are classically considered pathognomonic for osteogenesis imperfecta (OI). The purpose of this study was to distinguish the clinical manifestations of isolated olecranon fractures in patients with and without OI to help practitioners assess when further evaluation for OI may be necessary. All patients younger than 18 years old who were treated for an isolated olecranon fracture at a pediatric tertiary care center between 2009 and 2021 were identified. Patients without radiographs available for review, those with known skeletal dysplasia other than OI, and patients with multiple fractures (eg, polytraumas) or with concomitant dislocations were excluded. Of the 701 patients identified, 403 were included for analysis. Demographic variables, mechanism of injury, treatment type, and determination of OI diagnosis were collected. Patients with a previously confirmed diagnosis of OI or with genetic confirmation of OI following their fracture were designated as OI (+), and the remainder were designated OI (-). The Mann-Whitney U and χ2 tests were used to compare groups. Of the 403 patients, the median age was 7.8 years (interquartile range 5.2 to 12.5), and 270 (67%) were male. There were 14 confirmed cases of OI (3.5%). The OI (+) and OI (-) groups did not differ significantly by age or sex (P>0.05). OI (+) patients were more likely to sustain an injury from low-energy mechanisms (86% vs. 32%, P<0.001), sustain displaced fractures (86% vs. 21%, P<0.001) and undergo operative treatment (86% vs. 20%, P<0.001), and to report a history of previous fracture (79% vs. 16%, P<0.001) than OI (-) patients. 36% of OI (+) patients sustained a second olecranon fracture during the study period; there were no subsequent olecranon fractures in the OI (-) group. Isolated olecranon fractures may not be pathognomonic for OI. However, orthopaedists must be vigilant about the possibility of OI in patients who sustain displaced, isolated olecranon fractures under low-energy mechanisms with a history of previous fracture(s). Level III.

Steogenesis Imperfecta: An Overview

Osteogenesis Imperfecta (OI) or commonly referred to as brittle bone disease is a congenital connective tissue formation disorder characterized by bone fragility, osteopenia, skin disorders, blue sclera, dentinogenesis imperfecta (DI), and hearing loss. The diagnosis of Osteogenesis Imperfecta is based on history, clinical examination, lumbar bone density, bone biochemistry and radiographic findings. Diagnosis of osteogenesis imperfecta can be difficult and some primary skeletal disorders can be mixed with osteogenesis imperfecta. Management of OI requires a multidisciplinary approach such as endocrinologists, pediatricians, orthopedic surgeons, dentists, medical rehabilitation specialists, geneticists, psychologists, and occupational therapists. Bisphosphonate therapy has been shown to be effective in reducing pain, fracture frequency, and disability. Medical services such as bisphosphonate treatment and rehabilitation in individuals with OI have the long-term goal of optimizing the health and well-being of bone fragility and deformity.

Osteoarthritis in osteogenesis imperfecta: A nationwide register-based cohort study.

Osteogenesis Imperfecta (OI) is a genetic disease characterized by skeletal fragility. Collagen type 1 is found in many tissues and collagen abnormalities may result in organ specific symptomatology. Musculoskeletal pain is a known issue for patients with OI, osteoarthritis (OA) can be a likely cause. Only few studies have investigated the relationship between OI and OA but demonstrated a greater propensity in OI patients to develop rapidly progressing OA. Therefore, we wanted to investigate if OA is more frequent in patients with OI compared to the general population. To evaluate the risk of osteoarthritis in patients with OI. A Danish nationwide, population-based and register-based longitudinal open cohort study. From 1977 to 2019, all patients registered with an OI diagnosis and a reference population matched on age and sex 5:1. Sub-hazard ratios for any, hip, and knee osteoarthritis comparing the OI cohort to the reference population. We identified 907 patients with OI (493 women) and included 4535 patients in the reference population (2465 women). The Sub Hazard Ratio was 2.20 [95% CI 1.73-2.79] for any osteoarthritis with 11.4% of the OI population and 5.4% of the reference population being registered. We found lower incidences of upper extremity joint OA compared to lower joint OA, but upper extremity joint OA was significantly more frequent in the OI population 2.1% vs 0.6%, SHR 3.19 [95% CI 1.78-5.70]. Patients with OI have a higher risk of OA than the reference population. Osteogenesis Imperfecta (OI) is a hereditary connective tissue disorder with skeletal fragility and extraskeletal manifestations. Osteoarthritis is a frequent joint disease and the incidence increases with age. In a population-register-based study, the risk of osteoarthritis was higher in patients with OI at an earlier age compared to a reference population.

Clinical Manifestations and Medical Imaging of Osteogenesis Imperfecta: Fetal Through Adulthood.

The aim of this paper is to describe the varying clinical and imaging manifestations of Osteogenesis Imperfecta (OI) in the fetus, the child, and the adult. OI is a genetic disorder with mutation of Type 1 and non-type 1 collagen genes that results in disruption of multiple collagen based organ systems, most notably bones, often leading to "brittle bones". Additional features such as blue sclera, dentinogenesis imperfecta, joint and ligamentous hyperlaxity, hearing loss and cardiac defects may be present. Currently, there are at least 30 recognized genetic forms of OI. Given the multiple genes involved, variable genetic inheritance, and the wide range in phenotype, diagnosis can be challenging. While OI may sometimes be diagnosed in the fetus, patients with mild forms of OI may be diagnosed in childhood or even in adulthood. Imaging, including ultrasound, radiography, computed tomography, and magnetic resonance imaging, plays an important role in the diagnoses of OI in the fetus, the child, and the adult. Imaging is also crucial in identifying the many multisystem manifestations of OI. In particular, imaging can help differentiate manifestations of OI from injuries sustained in non-accidental trauma. Age, severity and manner of presentation of OI vary broadly depending on the specific genetic mutation involved, mode of inheritance, and age of the patient. Successful diagnosis of OI hinges on a detailed knowledge of the variable presentation and complications that may be encountered with this disease. CONCLUSION: In conclusion, OI comprises a heterogeneous group of genetic disorders responsible for bone fragility and additional connective tissue disorders, which can result in specific clinical and imaging findings in the fetus, the child, and the adult.

Multicenter Study of Pain in Osteogenesis Imperfecta

<h3>Research Objectives</h3> To investigate the frequency and type of pain by disease severity and the treatment of pain in individuals with osteogenesis imperfecta (OI), a genetic disorder and member of the rare disease family. <h3>Design</h3> Cross-sectional analysis. <h3>Setting</h3> Subjects were enrolled in a longitudinal multicenter study of OI. <h3>Participants</h3> The study included 558 individuals with a clinical or molecular diagnosis of OI, classified as OI type I (44%), type III (20%), type IV (27%), and other (9%). Median age was 12.4 years (0.0 - 67.2 years). <h3>Interventions</h3> N/A. <h3>Main Outcome Measures</h3> Rare Diseases Clinical Research Network, Brittle Bone Disorders Consortium: Clinical Assessment Instrument: presence, type of pain and pharmacological treatment used for pain relief. <h3>Results</h3> 62% of subjects reported pain (25% acute; 26% chronic; 11% acute & chronic). Acute pain did not change significantly across age groups (p=0.13), but the frequency of chronic pain increased with age, being highest in adults (p < 0.01). Acute pain was significantly more frequent in OI type III when compared with OI type I (p < 0.05). The prevalence of chronic pain did not vary significantly (p=0.69) across OI types. Pain was identified as a limitation to walking by 38% of individuals. Bisphosphonates (BPs) were the pharmacological treatment most frequently used (54% BP; 13% NSAIDs; 28% No treatment). Those with OI types III and IV receiving intravenous BPs treatment had less chronic pain compared with non-treated peers (p < 0.01). <h3>Conclusions</h3> A majority of individuals with OI experience pain. Chronic pain increases with age across all disease types while acute pain is more frequent in OI type III. The study underscores the need for additional research to address causes of pain, treatment effectiveness, and the impact of pain on mobility for individuals with OI. <h3>Author(s) Disclosuress</h3> The study was supported by 1) BBDC (1U54AR068069), a part of the NCATS RDCRN. BBDC is funded through ORDR, NCATS, NIAMS, NIDCR, and NICHD, 2) HHS/NIDILRR 90ARHF0006-01, 3) OREC at Marquette University, and 4) Shriners Hospitals for Children.

Clinical, genetic characteristics and treatment outcomes of children and adolescents with osteogenesis imperfecta: a two-center experience

ABSTRACT Background Osteogenesis imperfecta (OI), is a heritable, heterogeneous connective tissue disorder, characterized by fragile bones. There are conflicting results about genotype-phenotype correlations and efficiency of bisphosphonate treatment in this disorder. Aim We aimed to evaluate the clinical, genetic characteristics, and long-term follow-up results of children and adolescents with OI. Materials and methods A two-center retrospective study was conducted using demographic, clinical, and genetic data obtained from the medical records of the patients. Results Twenty-nine patients (62% male, median age; 3.6 years) with OI diagnosis from 26 families were included in the study. Thirteen different variants (nine were novel) were described in 16 patients in COL1A1, COL1A2, and P3H1 genes. Our siblings with homozygous P3H1 variants had a severe phenotype with intrauterine and neonatal fractures. Twenty-two patients were treated with bisphosphonates (17 of them with pamidronate, five with alendronate) with a median duration of 3.0 (1.6–4.8) years. Eleven patients (50%) suffered from fractures after the treatment. Haploinsufficiency variants in COL1A1 caused a milder skeletal phenotype with less fracture count and better treatment outcomes than structural variants. When compared with the anthropometric measurements at the initial diagnosis time, height Z-scores were lower on the last clinical follow-up (p = 0.009). Conclusions We could not find an obvious genotype-phenotype correlation in Turkish OI patients with COL1A1 or COL1A2 variants. Treatment with pamidronate was effective in reducing fracture counts, without any long-term adverse effects.

Targeted High-Throughput Sequencing Analysis Results of Osteogenesis Imperfecta Patients from Different Regions of Turkey

Objective: Osteogenesis imperfecta (OI) includes a group of disorders characterized by susceptibility to bone fractures with different severities. The increasing number of genes that may underlie the disorder, along with the broad phenotypic spectrum that overlaps with other skeletal diseases, provided a compelling case for the use of high-throughput sequencing (HTS) technology as an aid to OI diagnoses. The aim of this analysis was to present the data from our 5-year targeted HTS results, that includes the reporting of 9 novel and 24 known mutations, found in OI patients, from 5 different regions of Turkey. Materials and Methods: We performed a retrospective cross-sectional study, reporting the HTS results of 43 patients (23 female and 20 male; mean age: 9.5 years), directed to our center with a suspicion of OI between February 2015 and May 2020. Genetic analyses were also performed for 24 asymptomatic parents to aid the segregation analyses. We utilized an HTS panel targeting the coding regions of 57 genes associated with a reduction, increase, or abnormal development of bone mineralization. In addition, we sequenced the entire coding region of the IFITM5 gene through HTS. Results: Thirty-nine patients had at least one pathogenic/likely pathogenic variation (90.69%) in the COL1A1 (56.41%), COL1A2 (20.51%), FKBP10 (7.7%), P3H1 (5.13%), IFITM5 (5.13%), CTRAP (2.56%), or TMEM38B (2.56%) genes. Nine of the determined pathogenic/likely pathogenic variations were novel. The recurrent pathogenic mutations were c.1081C>T (p.Arg361Ter) (3/43), c.1405C>T (p.Arg469Ter) (2/43), and c.3749del (p.Gly1250AlafsTer81) in COL1A1 gene, along with c.-14C>T variation in the 5'UTR of the IFITM5 gene (2/43) and the c.890_897dup variation in the FKBP10 gene (2/43). Three out of 43 patients were carrying at least one additional variant of unknown significance, highlighting the importance of a multigene panel approach and segregation analyses. Conclusion: We suggest that a targeted HTS panel is a feasible tool for genetic diagnosis of OI in patients.

Multiple Bone Fractures in a Neonate with Osteogenesis Imperfecta: A Case Report

Osteogenesis Imperfecta (OI) is characterised by increased bone fractures. It is clinically and genetically a heterozygous disease of connective tissues. OI type 3 is the most severe, non lethal form which is caused by the mutation of caused by mutation of procollagen type1 A1 or A2(COL1A1 or COL1A2) genes. A one-day-old male baby with respiratory distress and multiple limb deformities was presented to the paediatric emergency department. The head appeared unduly large in comparison to the body and the anterior, posterior and lateral fontanelle were wide open. Sclera did not appear blue. Both upper limbs appeared short and stubby with diffuse swelling in the left arm. Both lower limbs appeared curved and were held in a frog-like position. Infantogram showed multiple calvarial fractures in the skull, multiple rib fractures, fracture of left humerus, bilateral ulna, left femur and there were multiple areas with callus formation suggestive of intrauterine fractures. There was no history of trauma during birth. Clinical diagnosis of OI was made and the neonate was managed medically. Genetic analysis could not be done owing to financial constraints. In conclusion, a high index of suspicion and careful clinical and radiological evaluation can identify very rare hereditary abnormalities like OI.

New 3D Cone Beam CT Imaging Parameters to Assist the Dentist in Treating Patients with Osteogenesis Imperfecta.

(1) Background: The aim of the work is to identify some imaging parameters in osteogenesis imperfecta to assist the dentist in the diagnosis, planning, and orthodontic treatment of Osteogenesis Imperfecta (OI) using 3D cone beam Computed Tomography (CBCT) and the Double Energy X-ray Absorptiometry (DEXA) technique. (2) Methods: 14 patients (9 males and 5 females; aged mean ± SD 15 ± 1.5) with a clinical-radiological diagnosis of OI were analyzed and divided into mild and moderate to severe forms. The patients’ samples were compared with a control group of 14 patients (8 males and 6 females; aged mean ± SD 15 ± 1.7), free from osteoporotic pathologies. (3) Results: The statistical analysis allowed us to collect four datasets: in the first dataset (C1 sick population vs. C1 healthy population), the t-test showed a p-value < 0.0001; in the second dataset (C2 sick population vs. C2 healthy population), the t-test showed a p-value < 0.0001; in the third dataset (parameter X of the sick population vs. parameter X of the healthy population), the t-test showed a p-value < 0.0001; in the fourth dataset the bone mineralometry (BMD) value detected by the DEXA technique compared to the C2 value of the OI affected population only) the Welch–Satterthwaite test showed a p-value < 0.0001. (4) Conclusions: The research has produced specific imaging parameters that assist the dentist in making diagnostic decisions in OI patients. This study shows that patients with OI have a characteristic chin-bearing symphysis, thinned, and narrowed towards the center, configuring it with a constant “hourglass” appearance, not reported so far in the literature by any author.

Morphological Characterization of Deciduous Enamel and Dentin in Patients Affected by Osteogenesis Imperfecta

The purpose of this study was to clarify the structural and ultrastructural alterations of the enamel and dentin collagen network in the deciduous teeth of children affected by osteogenesis imperfecta (OI) using field-emission in-lens scanning electron microscopy (FEI-SEM) and transmission electron microscopy (TEM) analyses. Exfoliated primary teeth were collected from children with a diagnosis of OI and from healthy individuals (N = 24). Tooth slices containing both dentin and enamel were fixed, dehydrated and dried, gold sputtered, and observed using FEI-SEM. Additional dentin fragments were decalcified, dehydrated, embedded in resin, cut, and processed for TEM analysis. Under FEI-SEM, the enamel in OI-affected children showed an irregular prism distribution with the enamel hydroxyapatite crystals unpacked. Ultrastructural correlative analysis of the dentin in patients affected by OI showed an altered collagen pattern with a low density. In some areas, teeth in OI patients showed a reduction in the number of dentinal tubules, with odontoblastic process missing in most of the tubules. The presence of altered dentine and enamel organization in OI children was firmly established at an ultrastructural level, but additional biochemical studies are necessary in order to clarify quantitatively and qualitatively the collagenic and non-collagenic proteins in this disorder.

P0058THE ROLE OF GENETICS IN INCOMPLETE DISTAL RENAL TUBULAR ACIDOSIS IN NEPHROLITHIASIS

Abstract Background and Aims Distal renal tubular acidosis (dRTA) is characterized by an impairment of urinary acidification resulting in a hyperchloremic non-anion gap metabolic acidosis, hypokalemia and inappropriately elevated urine pH. If not treated, this chronic condition eventually leads to nephrocalcinosis and recurrent nephrolithiasis, impaired renal function and bone demineralization due to reabsorption of bicarbonate and phosphate complexed with calcium from the bone as a buffer for metabolic acidosis. Distal RTA is therefore a well-defined entity that can be diagnosed by genetic testing of five genes known to be disease-causative (ATPV1B1 and ATPV0A4, FOXi1, SLC4A1 and WDR72). Incomplete distal renal tubular acidosis (idRTA) is defined as impaired urinary acidification that does not lead to overt metabolic acidosis and therefore can be diagnosed if patients fail to adequately acidify urine after an ammonium chloride (NH4Cl) challenge or other acid load tests. It is observed in 10-20% of calcium stone formers. It is still uncertain whether idRTA represents a distinct entity or it is part of the dRTA spectrum and whether it is caused by mutations in the same genes of overt dRTA. Heterozygous ATP6V1B1 pathogenic variants have been linked to idRTA, as well as mutations in SLC4A1. Method In this cross-sectional study we investigated a group of 23 stone formers whose clinical features were suspicious of idRTA: a history of nephrolithiasis or nephrocalcinosis with morning urinary pH &amp;gt; 5.8 in the absence of overt metabolic acidosis. They therefore underwent a simplified NH4Cl challenge and were found to have impaired urinary acidification ability. These patients were then analyzed by genetic testing with sequencing of 4 genes: SLC4A1, ATP6V1B1, ATP6V0A4 and FOXi1. Results Two unrelated individuals were found to have mutations in SLC4A1: 2 different variants in heterozygosis that had never been described before. The first patient was a 47-year old man, recurrent stone former (mainly apatite, but also some calcium oxalate), with hypercalciuria but normal bone mineral density (BMD). His family history revealed 1 uncle with kidney stones. The second patient was a 56-year old woman with a diagnosis of osteogenesis imperfecta, a history of reduced BMD and severe restrictive ventilation disorder and passed 1 stone (35% apatite, 65% CaOx). She was found to have bilateral nephrocalcinosis and hypocitraturia. Her family history revealed a sister with kidney stones. Conversely, 21 patients did not show any mutations for the genes sequenced, leading to a prevalence of genetic mutations of 8.7%. This is a much lower figure compared with overt dRTA, in which only 30% of patients with a clinical diagnosis of hereditary dRTA have no identified causative mutations in the currently known genes. Conclusion This suggests the involvement of other genes (WDR72 or others) or non-genetic tubular dysfunction in the pathogenesis of idRTA in stone formers.

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

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. 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. 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. 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.