Osteogenesis imperfecta in childhood: perceived competence in relation to impairment and disability.

OBJECTIVES: To examine the perceived competence of children with different types of osteogenesis imperfecta (OI) and to investigate the possible relationships between their perceived competence and impairment parameters. DESIGN: Cross-sectional study. SETTING: National referral center (hospital) for the treatment of children with OI. PATIENTS: Forty children with OI (type I = 17; type III = 11; type IV = 12) with a mean age +/- standard deviation of 12.6 +/- 3.2 years. INTERVENTIONS: Measured joint range of motion (ROM) in the upper extremities (UEs), and lower extremities (LEs), muscle strength, functional skills, ambulation, and perceived competence. MAIN OUTCOME MEASURES: Joint ROM in UE and LE; muscle strength (using the manual muscle testing criteria of the Medical Research Council); functional skills using the Pediatric Evaluation of Disability Inventory in 3 domains (self-care, mobility, social function). Ambulation (according to Bleck and classified as nonwalking, therapy walking, household walking, neighborhood walking, community walking with or without the use of crutches), and perceived competence (using the Harter Self-Perception Profile for Children, which was cross-culturally validated for Dutch children). RESULTS: In children with type I, joint ROM and muscle strength were almost comparable to the healthy population. In children with type III, a severe decrease in joint ROM was measured, especially in the LEs, and muscle strength was severely decreased in the UEs and LEs. In children with type IV, joint ROM and muscle strength decreased, especially in the LEs. In all types, fairly to strongly positive perceived competence was measured except for fairly negative perceived competence in the athletic performance subscale in type I and a fairly negative perceived competence in the romance subscale in type III. No correlations were found between (1) joint ROM and athletic performance and physical appearance, (2) muscle strength and athletic performance or physical appearance, or (3) the functional skills, concerning self-care and mobility, with the subscales of the perceived competence. CONCLUSIONS: Although joint ROM, muscle strength, and functional and walking ability were related to the severity of the disease and differed significantly between the different types of OI, overall perceived competence in children with OI was fairly to strongly positive, without significant differences between the different types of OI.     

Osteogenesis imperfecta: insufficient collagen synthesis in early childhood as evidenced by analysis of compact bone and fibroblast cultures

We analysed the composition of compact bone from 30 patients suffering from various forms of osteogenesis imperfecta (OI). Collagen and total protein content per cell of controls increased with the age of the donors, but were generally low in OI. In fibroblast cultures controls had a maximum of collagen synthesis between 2 and 9 years of age, an observation which was not seen in OI cells. In bone collagen both OI type II patients showed overhydroxylation of lysyl residues as did some patients with OI type III (25%) and OI type IV (33%). The collagen of OI type I patients was never found to be overmodified. In controls, collagen III was found exclusively during fetal time while it was present in significant amounts in bone tissue of all types of OI. The proportion of collagen V was somewhat higher in OI bones (about twice) than in controls. Our data suggest that the normal increase of collagen synthesis is defective in patients with OI. Perhaps some of these changes are due to specific molecular defects in collagen while others may be due to defective regulation of the maturation process.     

Osteogenesis imperfecta in childhood: impairment and disability. A prospective study with 4-year follow-up

OBJECTIVES: To study (1). changes in anthropometrics, joint range of motion (ROM), muscle strength, functional ability, caregiver assistance, and level of ambulation in children with osteogenesis imperfecta (OI) and (2). the prediction of clinical characteristics at the level of ambulation at follow-up and the prediction of clinical characteristics on progression or regression at the level of ambulation over time. DESIGN: Prospective study with follow-up of 4 years. SETTING: A children's hospital that serves a nationwide center for treatment and research in children with OI in the Netherlands. PARTICIPANTS: At follow-up, 49 children (24 boys, 25 girls; mean age +/- standard deviation, 11.3+/-3.8y; range, 5.2-19.4y) participated. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Anthropometry, joint ROM, muscle strength, fracture frequency, intramedullary rodding, level of ambulation, functional ability, and caregiver assistance. RESULTS: In type I OI, total joint ROM decreased significantly over time, especially in the lower extremities, with a significant decrease in generalized joint hypermobility according to Bulbena (median start, 7.5; interquartile range [IQR], 4-9; median end, 6; IQR, 2-7; P<.001). In types III and IV, a severe decrease in total joint ROM was present without significant changes over time. No significant changes in total muscle strength (upper or lower extremities) in the different types of OI were measured at follow-up. In OI type I, a significant increase in self-care (P=.003) and social function (P=.008) was measured; in type III, a significant increase in self-care (P=.003), mobility (P=.004), and social function (P=.005) was measured, with a significant decrease in parental assistance in self-care (P=.02) and mobility (P=.005). In type IV, a significant increase was observed in the self-care (P=.01) and social function domains (P=.02). Type of OI (regression coefficient=-1.0; 95% confidence interval [CI], -1.64 to -0.47) and total muscle strength were the only significant predictors for level of ambulation (regression coefficient=.01; 95% CI,.17-.32). Body weight was significantly lower in the group that progressed in level of ambulation (P=.03), whereas children with a decline in level of ambulation had significantly higher body weight (P=.05). CONCLUSIONS: Ours is the first study with a long-term follow-up that provides information concerning the natural course of developmental outcome parameters of OI in childhood. Joint ROM and muscle strength did not change significantly over time, possibly because of the biomechanical skeletal properties of the different OI types. Functional ability improved significantly over time, but, especially in types III and IV, did not reach normative values, possibly because of a plateau phase in functional ability. Knowledge of the natural course of the disease is essential to interpret the results from intervention studies.     

Osteogenesis Imperfecta Type I: Recognition in Primary Care

With a wide spectrum of severity, osteogenesis imperfecta (OI) is a connective tissue disease resulting in bone fragility. Approximately 25,000–50,000 Americans are afflicted with OI; 50% of these cases are classified as type I. Type I does not discriminate regarding ethnicity, race, or sex. The disease symptoms change across the life span and vary among patients; therefore, diagnosis is often missed. The aim of this article is to briefly explain etiology, clinical manifestations, common assessment findings, and recommended health promotion activities to recognize individuals with OI type I, thereby facilitating an early diagnosis and appropriate referrals.     

Bone formation markers in adults with mild osteogenesis imperfecta

BACKGROUND: Plasma concentrations of procollagen peptides are decreased in osteogenesis imperfecta (OI), whereas other bone formation markers may be increased. We examined the utility of combining these markers in the diagnosis of OI in adults. METHODS: We measured plasma concentrations of procollagen-1 N-peptide (P1NP), osteocalcin, and bone alkaline phosphatase in 24 patients with nondeforming OI, 25 patients with low bone mass due to other causes, and 38 age- and sex-matched controls. The discriminant ability of various test combinations was assessed by the construction of ROC curves. RESULTS: The median (range) ratio of osteocalcin to P1NP was significantly greater in patients with type I OI [1.75 (0.80-3.86)] than in controls [0.59 (0.34-0.90)] and patients with other causes of low bone mass [0.48 (0.05-1.38); P <0.0001]. This ratio allowed nearly complete differentiation between healthy controls and patients with type I OI, but not patients with type IV OI. With a cutoff of 0.97 for osteocalcin:P1NP, the sensitivity and specificity were maximized at 95% (95% CI 76%-100%) and 88% (69%-97%), respectively, for patients with other causes of low bone mass vs those with type I OI only. For patients with other causes of low bone mass vs all OI patients, sensitivity and specificity were 83% (63%-95%) and 88% (69%-97%), respectively. The addition of bone alkaline phosphatase data did not improve the discriminant ability of the osteocalcin:P1NP ratio. CONCLUSIONS: The osteocalcin:P1NP ratio is a sensitive and specific test for type I OI in adults, but it has less utility in the diagnosis of other types of nondeforming OI.     

Altered collagen metabolism in osteogenesis imperfecta fibroblasts: a study on 33 patients with diverse forms

The pattern of collagen metabolism was analysed in fibroblast cultures from patients with diverse forms of osteogenesis imperfecta (OI). Generally, OI fibroblasts show an insufficient collagen synthesis which is most obvious in patients between 2 and 9 years of age during which period control fibroblasts have an elevated collagen synthesis. OI fibroblasts remain on a basal level except for fibroblasts from OI type IV patients which seem to approach normal levels. In addition, OI fibroblasts generally show a slightly increased degradation of newly synthesized collagen which again is most obvious between 2 and 9 years. These differences in collagen degradation, however, only contribute to a minor extent to the lack of net collagen synthesis during early childhood. No correlation could be found between the degree of overmodification of collagen and its degradation since fibroblasts of both OI type I and OI type II have an elevated degradation though only the latter ones produce overmodified collagen molecules. Pulse labelling of collagen with radioactivity labelled sugars was used to distinguish between normal collagen chains or CNBr-derived peptides and those which were overmodified. In all three cases studied (OI II, OI III, OI IV) the entire triple helical domain of alpha 1(I) and alpha 2(I) was overglycosylated. The amount of overmodification, however, was not uniform but rather unique for each patient studied. We assume that the molecular defects in the majority of OI cases may be located in the mechanisms operating on the control of both the age appropriate synthesis of collagen and its degree of post-translational modification.     

Altered collagen metabolism in osteogenesis imperfecta fibroblasts: a study on 33 patients with diverse forms

Abstract. The pattern of collagen metabolism was analysed in fibroblast cultures from patients with diverse forms of osteogenesis imperfecta (OI). Generally, OI fibroblasts show an insufficient collagen synthesis which is most obvious in patients between 2 and 9 years of age during which period control fibroblasts have an elevated collagen synthesis. OI fibroblasts remain on a basal level except for fibroblasts from OI type IV patients which seem to approach normal levels. In addition, OI fibroblasts generally show a slightly increased degradation of newly synthesized collagen which again is most obvious between 2 and 9 years. These differences in collagen degradation, however, only contribute to a minor extent to the lack of net collagen synthesis during early childhood. No correlation could be found between the degree of overmodification of collagen and its degradation since fibroblasts of both OI type I and OI type II have an elevated degradation though only the latter ones produce overmodified collagen molecules. Pulse labelling of collagen with radioactivity labelled sugars was used to distinguish between normal collagen chains or CNBr-derived peptides and those which were overmodified. In all three cases studied (OI II, OI III, OI IV) the entire triple helical domain of α 1(1) and α2(I) was overglycosylated. The amount of overmodification, however, was not uniform but rather unique for each patient studied. We assume that the molecular defects in the majority of OI cases may be located in the mechanisms operating on the control of both the age appropriate synthesis of collagen and its degree of post-translational modification.     

Results of a prospective pilot trial on mobility after whole body vibration in children and adolescents with osteogenesis imperfecta

OBJECTIVE: To evaluate the effect of whole body vibration on the mobility of long-term immobilized children and adolescents with a severe form of osteogenesis imperfecta. Osteogenesis imperfecta is a hereditary primary bone disorder with a prevalence from 1 in 10000 to 1 in 20000 births. Most of these children are suffering from long-term immobilization after recurrent fractures. Due to the immobilization they are affected by loss of muscle (sarcopenia) and secondary loss of bone mass. SUBJECTS: Whole body vibration was applied to eight children and adolescents (osteogenesis imperfecta type 3, N=5; osteogenesis imperfecta type 4, N=3) over a period of six months. INTERVENTIONS AND RESULTS: Whole body vibration was applied by a vibrating platform (Galileo Systems) constructed on a tilting-table. Success of treatment was assessed by measuring alterations of the tilting-angle and evaluating the mobility (Brief Assessment of Motor Function). All individuals were characterized by improved muscle force documented by an increased tilting-angle (median = 35 degrees) or by an increase in ground reaction force (median at start=30.0 [N/kg] (14.48-134.21); median after six months = 146.0 [N/kg] (42.46-245.25). CONCLUSIONS: Whole body vibration may be a promising approach to improve mobility in children and adolescents severely affected with osteogenesis imperfecta.     

Biochemical analysis of callus tissue in osteogenesis imperfecta type IV. Evidence for transient overmodification in collagen types I and III.

We analyzed tissue and cells from a stationary and a rapidly growing hyperplastic callus from a patient with osteogenesis imperfecta (OI) type IV and compared the results with those of compact bone and skin fibroblasts of an age-matched control. Collagen and protein contents per cell were low in the callus tissues and collagen I and III were overmodified as evidenced by an elevated level of hydroxylysine. The degree of lysyl hydroxylation was highest in those regions that appeared most immature by histological examination. Lysyl hydroxylation approached normal levels in collagen from the stationary callus and from the center of the growing callus. Overmodification of collagen was not seen in compact bone or cell cultures (neither skin fibroblasts nor callus cells) from the patient. Elevation of hydroxylysine in collagen from OI patients is generally attributed to mutations that delay triple helix formation. Our observations suggest that the varying degree of collagen modifications may occur in consequence of regulatory mechanisms during bone development and tissue repair. These mechanisms may be defective in some patients with OI as seen in this case with hyperplastic callus formation.     

Variable prenatal appearance of osteogenesis imperfecta.

Osteogenesis imperfecta is a heterogeneous group of disorders of type I collagen with both lethal and nonlethal forms. Prenatal sonographic findings in affected fetuses are variable and depend on the severity of the disease. Six cases of osteogenesis imperfecta in which prenatal sonography had been performed were reviewed. Two cases of lethal type II osteogenesis imperfecta revealed short femurs at 16 to 17 weeks' gestation with development of bowing and fractures by 19 weeks' gestation. Four fetuses with the nonlethal type III or IV had femoral bowing with or without shortening in the late second or third trimester with grossly normal mineralization. Fractures in this latter group did not develop until 1 to 12 months after delivery. Understanding the progressive nature and variability of osteogenesis imperfecta is crucial in the prenatal diagnosis and management of this disease.     

Reduced strength of skin in osteogenesis imperfecta

The biochemical properties and ratio collagen type I/type III of skin biopsies from nine patients with osteogenesis imperfecta and nine age- and sex-matched controls were studied. Four of six patients with osteogenesis imperfecta Sillence type I had pronounced reductions in skin tensile strength, decreased ratios of collagen type I/type III, primarily accomplished by reduced amounts of collagen type I, moderate or no disability. The three patients with osteogenesis imperfecta Sillence type III had severe skeletal deformities, but normal skin tensile strength, and ratios of collagen type I/type III within the normal range. These observations may be explained as resulting from various structural defects in the type I collagen of patients with osteogenesis imperfecta.     

Fetus with osteogenesis imperfecta presenting as increased nuchal translucency thickness in the first trimester

Type II osteogenesis imperfecta (OI) is a perinatally lethal disorder due to type I collagen abnormalities that has been diagnosed successfully in the second trimester. We report a case of type II OI that was confirmed on postmortem histology and radiography presenting as increased nuchal translucency in the first trimester.     

Fetal biometry of skeletal dysplasias: a multicentric study.

Twenty-three diagnostic centers worldwide contributed 127 cases of 17 skeletal dysplasias. Discriminant analysis showed that the femur length was the best biometric parameter to distinguish among the five most common disorders in this series (thanatophoric dysplasia, osteogenesis imperfecta type II, achondrogenesis, achondroplasia and hypochondroplasia). Fifty-four percent of fetuses with femur length below 30% of the mean for gestational age had achondrogenesis. Seventy-eight percent of measurements between 40 and 60% of the mean for gestational age represented either thanatophoric dysplasia or osteogenesis imperfecta type II. Fetuses who had over 80% of the mean for gestational age had predominantly hypochondroplasia, achondroplasia, and osteogenesis imperfecta type III.     

Fetal biometry of skeletal dysplasias: a multicentric study.

Twenty-three diagnostic centers worldwide contributed 127 cases of 17 skeletal dysplasias. Discriminant analysis showed that the femur length was the best biometric parameter to distinguish among the five most common disorders in this series (thanatophoric dysplasia, osteogenesis imperfecta type II, achondrogenesis, achondroplasia and hypochondroplasia). Fifty-four percent of fetuses with femur length below 30% of the mean for gestational age had achondrogenesis. Seventy-eight percent of measurements between 40 and 60% of the mean for gestational age represented either thanatophoric dysplasia or osteogenesis imperfecta type II. Fetuses who had over 80% of the mean for gestational age had predominantly hypochondroplasia, achondroplasia, and osteogenesis imperfecta type III.     

Targeting TGF-β for treatment of osteogenesis imperfecta

BACKGROUNDCurrently, there is no disease-specific therapy for osteogenesis imperfecta (OI). Preclinical studies demonstrate that excessive TGF-β signaling is a pathogenic mechanism in OI. Here, we evaluated TGF-β signaling in children with OI and conducted a phase I clinical trial of TGF-β inhibition in adults with OI.METHODSHistology and RNA-Seq were performed on bones obtained from children. Gene Ontology (GO) enrichment assay, gene set enrichment analysis (GSEA), and Ingenuity Pathway Analysis (IPA) were used to identify dysregulated pathways. Reverse-phase protein array, Western blot, and IHC were performed to evaluate protein expression. A phase I study of fresolimumab, a TGF-β neutralizing antibody, was conducted in 8 adults with OI. Safety and effects on bone remodeling markers and lumbar spine areal bone mineral density (LS aBMD) were assessed.RESULTSOI bone demonstrated woven structure, increased osteocytes, high turnover, and reduced maturation. SMAD phosphorylation was the most significantly upregulated GO molecular event. GSEA identified the TGF-β pathway as the top activated signaling pathway, and IPA showed that TGF-β1 was the most significant activated upstream regulator mediating the global changes identified in OI bone. Treatment with fresolimumab was well-tolerated and associated with increases in LS aBMD in participants with OI type IV, whereas participants with OI type III and VIII had unchanged or decreased LS aBMD.CONCLUSIONIncreased TGF-β signaling is a driver pathogenic mechanism in OI. Anti–TGF-β therapy could be a potential disease-specific therapy, with dose-dependent effects on bone mass and turnover.TRIAL REGISTRATIONClinicalTrials.gov {"type":"clinical-trial","attrs":{"text":"NCT03064074","term_id":"NCT03064074"}}NCT03064074.FUNDINGBrittle Bone Disorders Consortium (U54AR068069), Clinical Translational Core of Baylor College of Medicine Intellectual and Developmental Disabilities Research Center (P50HD103555) from National Institute of Child Health and Human Development, USDA/ARS (cooperative agreement 58-6250-6-001), and Sanofi Genzyme.     

Osteogenesis imperfecta type IV. Biochemical confirmation of genetic linkage to the pro alpha 2(I) gene of type I collagen.

Fibroblasts from two affected members of a large pedigree in which osteogenesis imperfecta (OI) type IV is genetically linked to the pro alpha 2(I) gene of type I collagen synthesize two populations of pro alpha 2(I) chains. One population is normal; the second population appears to have a deletion of about 10 amino acid residues from the middle of the triple helical domain. The mutation in pro alpha 2(I) causes increased posttranslational modification in the amino-terminal half of some pro alpha 1(I) chains, lowers the melting temperature of type I collagen molecules that incorporate a mutant pro alpha 2(I) chain, and prevents or delays the secretion of those molecules from fibroblasts in cell culture. On the basis of this study and linkage studies in additional families, it appears that the OI type IV phenotype is often the result of heterozygosity for mutations in pro alpha 2(I) that alter the triple helical structure of type I collagen.     

A population-based study of demographical variables and ability to perform activities of daily living in adults with osteogenesis imperfecta

Purposes.?To describe demographical variables, and to study functional ability to perform activities of daily life in adults with osteogenesis imperfecta (OI).

Methods.?Population-based study. Ninety-seven patients aged 25 years and older, 41 men and 56 women, were included. For the demographical variables, comparison was made to a matched control-group (475 persons) from the Norwegian general population. Structured interviews concerning social conditions, employment and educational issues and clinical examination were performed. The Sunnaas Activities of Daily Living (ADL) Index was used to assess the ability to perform ADL.

Results.?The prevalence of clinical manifestations according to Sillence was in accordance with other studies. Demographical variables showed that most adults with OI are married and have children. They had a higher educational level than the control group, but the employment rate was significantly lower. However, the rate of employed men was similar in both groups. Adult persons with OI achieved a high score when tested for ADL.

Conclusions.?Adults with OI are well educated compared with the general population, and most of them are employed. High scores when tested for ADL indicate that most of them are able to live their lives independently, even though there are some differences according to the severity of the disorder.     

Determinants of functioning of adolescents and young adults with cerebral palsy

Purpose. To describe the level of functioning of adolescents and young adults with cerebral palsy (CP) and study determinants of their level of functioning.

Method. In the CP Transition study, adolescents and young adults aged 16 – 20 years, diagnosed with CP without severe learning disabilities (n = 103) participated. In this group we assessed subject characteristics, i.e., age, type of CP, gross motor function (GMFCS), level of education as well as outcome measures on functioning in daily activities and social participation (Life Habits questionnaire, Vineland Adaptive Behavior Scale, Functional Independence Measure). Multivariate regression analyses were performed.

Results. About 20 – 30% of the participants encountered restrictions in daily activities (mobility, self-care, nutrition) and social participation (taking responsibility, community living, leisure activities and employment). The GMFCS level, level of education, and age proved to be important determinants of functioning in daily activities and social participation, explaining 70% and 66% of the variance in outcome respectively.

Conclusion. A significant number of adolescents and young adults with CP without severe learning disabilities are restricted in daily activities and social participation. These problems are mainly attributable to restricted gross motor functioning, a low level of education and younger age.     

An unusual pattern of peptide-bound lysine metabolism in collagen from an infant with lethal perinatal osteogenesis imperfecta

Collagens extracted from bones, cartilage, dermis, and dura mater of an infant with type II (lethal perinatal) osteogenesis imperfecta were evaluated with respect to chain composition and chemical characteristics of their constituent chains. The results indicated that the various types of collagen were present in the indicated tissues in proportions that approximated normal tissues. Nevertheless, the constituent chains of collagens extracted from dermis, i.e., alpha 1(I), alpha 2(I), alpha 1(III), alpha 1(V), and alpha 2(V), chromatographed on carboxymethyl cellulose as though they possessed substantially lower overall positive charge than the homologous chains of normal tissues. Amino acid analyses of the chains confirmed this observation and showed that the chains lacked five to seven residues of lysine (plus hydroxylysine). It was subsequently shown that the apparent deficiency in lysyl residues was due, at least in part, to the presence of unusually high levels of allysine , a cross-link precursor formed from peptide-bound lysine under the catalytic action of lysyl oxidase. These results, in conjunction with previous results obtained on collagens from type II osteogenesis imperfecta tissues, suggest that aberrant fibril formation in this syndrome allows increased lysyl oxidase activity.