RNA sequencing analysis reveals increased expression of interferon signaling genes and dysregulation of bone metabolism affecting pathways in the whole blood of patients with osteogenesis imperfecta

BACKGROUND

Osteogenesis imperfecta (OI) is a rare genetic disorder in which the patients suffer from numerous fractures, skeletal deformities and bluish sclera. The disorder ranges from a mild form to severe and lethal cases. The main objective of this pilot study was to compare the blood transcriptional landscape of OI patients with COL1A1 pathogenic variants and their healthy relatives, in order to find out different gene expression and dysregulated molecular pathways in OI.

METHODS

We performed RNA sequencing analysis of whole blood in seven individuals affected with different OI severity and their five unaffected relatives from the three families. The data was analyzed using edgeR package of R Bioconductor. Functional profiling and pathway analysis of the identified differently expressed genes was performed with g:GOSt and MinePath web-based tools.

RESULTS

We identified 114 differently expressed genes. The expression of 79 genes was up-regulated, while 35 genes were down-regulated. The functional analysis identified a presence of dysregulated interferon signaling pathways (IFI27, IFITM3, RSAD12, GBP7). Additionally, the expressions of the genes related to extracellular matrix organization, Wnt signaling, vitamin D metabolism and MAPK-ERK 1/2 pathways were also altered.

CONCLUSIONS

The current pilot study successfully captured the differential expression of inflammation and bone metabolism pathways in OI patients. This work can contribute to future research of transcriptional bloodomics in OI. Transcriptional bloodomics has a strong potential to become a major contributor to the understanding of OI pathological mechanisms, the discovery of phenotype modifying factors, and the identification of new therapeutic targets. However, further studies in bigger cohorts of OI patients are needed to confirm the findings of the current work.

Alterations in non-type I collagen biomarkers in osteogenesis imperfecta

Osteogenesis imperfecta [1] is a rare disorder of connective tissue caused by abnormalities in the synthesis or processing of type I collagen. Type I collagen is the most abundant type of collagen and is expressed in almost all connective tissues. Given that type I collagen interacts with other collagens based in the extracellular matrix (ECM), we hypothesized changes in type I collagen in OI would result in perturbations in the homeostasis of other collagen types. We measured serum biomarkers of several non-type I collagens in patients with mild (type I) and moderate-to-severe (type III/IV) OI. Compared to controls, those with moderate-to severe OI had a higher mean level of the synthesis markers of collagen III (ProC3) (P = 0.02), and levels of collagen V (ProC5) (P = 0.07) were slightly, but not significantly, higher. Degradation markers of collage type IV (C4M2) (P = 0.04) and type VI (C6M) (P = 0.003) were also higher. In each case, a test for trend suggested levels were higher in moderate-to-severe OI, intermediate in mild OI, and lowest in controls (P = 0.06-0.002). These changes supports the hypothesis that mutations in type I collagen induce a widespread alteration in the ECM, and that the diverse clinical manifestations of OI reflect an extensive disruption in ECM biology.

Skeletal Response to Soluble Activin Receptor Type IIB in Mouse Models of Osteogenesis Imperfecta

Osteogenesis imperfecta (OI) is a heritable connective tissue disorder primarily due to mutations in the type I collagen genes (COL1A1 and COL1A2), leading to compromised biomechanical integrity in type I collagen-containing tissues such as bone. Bone is inherently mechanosensitive and thus responds and adapts to external stimuli, such as muscle mass and contractile strength, to alter its mass and shape. Myostatin, a member of the TGF-β superfamily, signals through activin receptor type IIB to negatively regulate muscle fiber growth. Because of the positive impact of myostatin deficiency on bone mass, we utilized a soluble activin receptor type IIB-mFc (sActRIIB-mFc) fusion protein in two molecularly distinct OI mouse models (G610C and oim) and evaluated their bone properties. Wild-type (WT), +/G610C, and oim/oim mice were treated from 2 to 4 months of age with either vehicle (Tris-buffered saline) or sActRIIB-mFc (10 mg/kg). Femurs of sActRIIB-mFc-treated mice exhibited increased trabecular bone volume regardless of genotype, whereas the cortical bone microarchitecture and biomechanical strength were only improved in WT and +/G610C mice. Dynamic histomorphometric analyses suggest the improved cortical bone geometry and biomechanical integrity reflect an anabolic effect due to increased mineral apposition and bone formation rates, whereas static histomorphometric analyses supported sActRIIB-mFc treatment also having an anti-catabolic impact with decreased osteoclast number per bone surface on trabecular bone regardless of sex and genotype. Together, our data suggest that sActRIIB-mFc may provide a new therapeutic direction to improve both bone and muscle properties in OI. © 2018 American Society for Bone and Mineral Research.

EFFECTS OF LONG-TERM ALENDRONATE TREATMENT ON A LARGE SAMPLE OF PEDIATRIC PATIENTS WITH OSTEOGENESIS IMPERFECTA

OBJECTIVE

Osteogenesis imperfecta (OI) is a group of inherited diseases characterized by reduced bone mass, recurrent bone fractures, and progressive bone deformities. Here, we evaluate the efficacy and safety of long-term treatment with alendronate in a large sample of Chinese children and adolescents with OI.

METHODS

In this prospective study, a total of 91 children and adolescents with OI were included. The patients received 3 years' treatment with 70 mg alendronate weekly and 500 mg calcium daily. During the treatment, fracture incidence, bone mineral density (BMD), and serum levels of the bone turnover biomarkers (alkaline phosphatase [ALP] and cross-linked C-telopeptide of type I collagen [β-CTX]) were evaluated. Linear growth speed and parameters of safety were also measured.

RESULTS

After 3 years of treatment, the mean annual fracture incidence decreased from 1.2 ± 0.8 to 0.2 ± 0.3 (P<.01). BMD at the lumbar spine and femoral neck significantly increased by 74.6% and 39.5%, with their BMD Z-score increasing from -3.0 to 0.1 and from -4.2 to -1.3, respectively (both P<.01 vs. baseline). In addition, serum ALP and β-CTX levels decreased by 35.6% and 44.3%, respectively (both P<.05 vs. baseline). Height significantly increased, but without an obvious increase in its Z-score. Patient tolerance of alendronate was good.

CONCLUSION

Three years' treatment with alendronate was demonstrated for the first time to significantly reduce fracture incidence, increase lumbar spine and femoral neck BMD, and decrease bone turnover biomarkers in Chinese children and adolescents with OI.

ABBREVIATIONS

ALP = alkaline phosphatase β-CTX = cross-linked C-telopeptide of type I collagen BMD = bone mineral density BP = bisphosphonate DXA = dual-energy X-ray absorptiometry 25OHD = 25-hydroxyvitamin D OI = osteogenesis imperfecta PTH = parathyroid hormone.

Children with severe Osteogenesis imperfecta and short stature present on average with normal IGF-I and IGFBP-3 levels

BACKGROUND

Osteogenesis imperfecta (OI) is characterized by bone fragility and short stature. Data about IGF-I/IGFBP-3 levels are rare in OI. Therefore IGF-I/IGFBP-3 levels in children with different types of OI were investigated.

METHODS

IGF-I and IGFBP-3 levels of 60 children (male n=38) were assessed in a retrospective cross-sectional setting.

RESULTS

Height/weight was significant different [height z-score type 3 versus type 4: p=0.0011 and weight (p≤0.0001)] between OI type 3 and 4. Mean IGF-I levels were in the lower normal range (mean±SD level 137.4±109.1 μg/L). Mean IGFBP-3 measurements were in the normal range (mean±SD 3.105±1.175 mg/L). No significant differences between OI type 3 and 4 children have been observed (IGF-I: p=0.0906; IGFBP-3: p=0.2042).

CONCLUSIONS

Patients with different severities of OI have IGF-I and IGFBP-3 levels in the lower normal range. The type of OI does not significantly influence these growth factors.

Effect of high-dose vitamin D supplementation on bone density in youth with osteogenesis imperfecta: A randomized controlled trial

Osteogenesis imperfecta (OI) is a heritable condition characterized by fragile bones. Our previous studies indicated that serum 25-hydroxyvitamin D (25OHD) concentrations were positively associated with lumbar spine areal bone mineral density (LS-aBMD) in children and adolescents with OI. Here we assessed whether one year of high-dose vitamin D supplementation results in higher LS-aBMD z-scores in youth with OI. A one-year double-blind randomized controlled trial conducted at a pediatric orthopedic hospital in Montreal, Canada. Sixty patients (age: 6.0 to 18.9years; 35 female) were randomized in equal numbers to receive either 400 or 2000international units (IU) of vitamin D, stratified according to baseline bisphosphonate treatment status and pubertal stage. At baseline, the average serum 25OHD concentration was 65.6nmol/L (SD 20.4) with no difference between treatment groups (p=0.77); 21% of patients had results <50nmol/L. Vitamin D supplementation was associated with higher serum 25OHD concentrations in 90% of participants. The increase in mean 25OHD was significantly higher (p=0.02) in the group receiving 2000IU of vitamin D (mean [95% CI]=30.5nmol/L [21.3; 39.6]) than in the group receiving 400IU (15.2nmol/L [6.4; 24.1]). No significant differences in LS-aBMD z-score changes were detected between treatment groups. Thus, supplementation with vitamin D at 2000IU increased serum 25OHD concentrations in children with OI more than supplementation with 400IU. However, in this study where about 80% of participants had baseline serum 25OHD concentrations ≥50nmol/L, this difference had no detectable effect on LS-aBMD z-scores.

Rapidly growing Brtl/+ mouse model of osteogenesis imperfecta improves bone mass and strength with sclerostin antibody treatment

Osteogenesis imperfecta (OI) is a heritable collagen-related bone dysplasia, characterized by brittle bones with increased fracture risk that presents most severely in children. Anti-resorptive bisphosphonates are frequently used to treat pediatric OI and controlled clinical trials have shown that bisphosphonate therapy improves vertebral outcomes but has little benefit on long bone fracture rate. New treatments which increase bone mass throughout the pediatric OI skeleton would be beneficial. Sclerostin antibody (Scl-Ab) is a potential candidate anabolic therapy for pediatric OI and functions by stimulating osteoblastic bone formation via the canonical Wnt signaling pathway. To explore the effect of Scl-Ab on the rapidly growing OI skeleton, we treated rapidly growing 3week old Brtl/+ mice, harboring a typical heterozygous OI-causing Gly→Cys substitution on col1a1, for 5weeks with Scl-Ab. Scl-Ab had anabolic effects in Brtl/+ and led to new cortical bone formation and increased cortical bone mass. This anabolic action resulted in improved mechanical strength to WT Veh levels without altering the underlying brittle nature of the material. While Scl-Ab was anabolic in trabecular bone of the distal femur in both genotypes, the effect was less strong in these rapidly growing Brtl/+ mice compared to WT. In conclusion, Scl-Ab was able to stimulate bone formation in a rapidly growing Brtl/+ murine model of OI, and represents a potential new therapy to improve bone mass and reduce fracture risk in pediatric OI.

Effect of sclerostin antibody treatment in a mouse model of severe osteogenesis imperfecta

Osteogenesis imperfecta (OI) is a heritable bone fragility disorder that is usually caused by mutations affecting collagen type I production in osteoblasts. Stimulation of bone formation through sclerostin antibody treatment (Sost-ab) has shown promising results in mouse models of relatively mild OI. We assessed the effect of once-weekly intravenous Sost-ab injections for 4weeks in male Col1a1(Jrt)/+mice, a model of severe dominant OI, starting either at 4weeks (growing mice) or at 20weeks (adult mice) of age. Sost-ab had no effect on weight or femur length. In OI mice, no significant treatment-associated differences in serum markers of bone formation (alkaline phosphatase activity, procollagen type I N-propeptide) or resorption (C-telopeptide of collagen type I) were found. Micro-CT analyses at the femur showed that Sost-ab treatment was associated with higher trabecular bone volume and higher cortical thickness in wild type mice at both ages and in growing OI mice, but not in adult OI mice. Three-point bending tests of the femur showed that in wild type but not in OI mice, Sost-ab was associated with higher ultimate load and work to failure. Quantitative backscattered electron imaging of the femur did not show any effect of Sost-ab on CaPeak (the most frequently occurring calcium concentration in the bone mineral density distribution), regardless of genotype, age or measurement location. Thus, Sost-ab had a larger effect in wild type than in Col1a1(Jrt)/+mice. Previous studies had found marked improvements of Sost-ab on bone mass and strength in an OI mouse model with a milder phenotype. Our data therefore suggest that Sost-ab is less effective in a more severely affected OI mouse model.

Adult Brtl/+ mouse model of osteogenesis imperfecta demonstrates anabolic response to sclerostin antibody treatment with increased bone mass and strength

Treatments to reduce fracture rates in adults with osteogenesis imperfecta are limited. Sclerostin antibody, developed for treating osteoporosis, has not been explored in adults with OI. This study demonstrates that treatment of adult OI mice respond favorably to sclerostin antibody therapy despite retention of the OI-causing defect.

INTRODUCTION

Osteogenesis imperfecta (OI) is a heritable collagen-related bone dysplasia, characterized by brittle bones with increased fracture risk. Although OI fracture risk is greatest before puberty, adults with OI remain at risk of fracture. Antiresorptive bisphosphonates are commonly used to treat adult OI, but have shown mixed efficacy. New treatments which consistently improve bone mass throughout the skeleton may improve patient outcomes. Neutralizing antibodies to sclerostin (Scl-Ab) are a novel anabolic therapy that have shown efficacy in preclinical studies by stimulating bone formation via the canonical wnt signaling pathway. The purpose of this study was to evaluate Scl-Ab in an adult 6 month old Brtl/+ model of OI that harbors a typical heterozygous OI-causing Gly > Cys substitution on Col1a1.

METHODS

Six-month-old WT and Brtl/+ mice were treated with Scl-Ab (25 mg/kg, 2×/week) or Veh for 5 weeks. OCN and TRACP5b serum assays, dynamic histomorphometry, microCT and mechanical testing were performed.

RESULTS

Adult Brtl/+ mice demonstrated a strong anabolic response to Scl-Ab with increased serum osteocalcin and bone formation rate. This anabolic response led to improved trabecular and cortical bone mass in the femur. Mechanical testing revealed Scl-Ab increased Brtl/+ femoral stiffness and strength.

CONCLUSION

Scl-Ab was successfully anabolic in an adult Brtl/+ model of OI.

Circulating sclerostin in children and young adults with heritable bone disorders

CONTEXT

Sclerostin is an inhibitor of bone formation and is an important determinant of bone mass. The role of sclerostin in heritable metabolic bone disorders has not been studied in detail.

OBJECTIVE

We evaluated serum sclerostin levels in patients with X-linked hypophosphatemic rickets (XLH) and osteogenesis imperfecta (OI) and analyzed the relationship of circulating sclerostin concentrations with lumbar spine areal bone mineral density (LS-aBMD).

SETTING

The study was conducted in the metabolic bone clinic of a pediatric orthopedic hospital.

PATIENTS

Participants were 128 individuals, including 30 patients with XLH, 76 patients with OI types I, III, and IV, and 22 healthy subjects.

MAIN OUTCOME MEASURES

Sclerostin was quantified in serum samples.

RESULTS

Patients with XLH had higher circulating sclerostin concentrations (mean [SD]: 30.2 [16.7] pmol/L) than healthy control subjects (21.4 [9.2] ng/mL) (P = .02), as well as relatively high LS-aBMD Z-scores (+1.1 [1.7]). In the XLH cohort, serum sclerostin levels were positively associated with the LS-aBMD Z-score (r = 0.56; P < .002) and with alkaline phosphatase (r = 0.45; P = .01). In patients with OI, sclerostin serum levels were similar to those of healthy control subjects despite low LS-aBMD.

CONCLUSIONS

The elevated sclerostin serum levels in XLH and the normal concentrations in OI suggest that the bone mass abnormalities in these disorders are not caused by primary sclerostin dysregulation.

Complement component C3: Serologic signature for osteogenesis imperfecta. Analysis of a comparative proteomic study

BACKGROUND/PURPOSE

Osteogenesis imperfecta (OI) is a disease characterized by low bone mass and bony fragility. This study investigated the serum proteomic profiles and their correlation with bone density for OI cases.

METHODS

Twenty OI patients and 20 control participants were included. Comparative serum proteomic profiles were analyzed by two-dimensional electrophoresis and tandem mass spectrometry. Serum protein levels were measured by enzyme-linked immunosorbent assay. Cutoff values and areas under the curve were estimated by the receiver operating characteristic curve. Bone mineral density data was obtained from all OI patients.

RESULTS

Candidate proteins identified by electrophoresis were complement component C3 (C3), vitamin D-binding protein (DBP), and haptoglobin (HP). Enzyme-linked immunosorbent assay validation showed that OI patients had decreased C3 and DBP and increased HP. The results were not affected by age or bisphosphonate use. Serum C3 levels significantly correlated with bone mineral density of the lumbar spine and hip. C3 had the greatest areas under the curve to distinguish OI from healthy controls.

CONCLUSION

Serum C3, DBP, and HP are emerging serologic signatures for OI. Concentrations of serum C3 correlated with the T score of OI patients. C3 had the greatest areas under the curve of the three proteins to distinguish OI from healthy controls.

Serum sclerostin levels are decreased in adult patients with different types of osteogenesis imperfecta

CONTEXT

There are no specific biochemical bone markers available for osteogenesis imperfecta (OI), and the role of sclerostin as a key regulator of bone formation in OI is unknown.

OBJECTIVES

We aimed to evaluate the role of sclerostin and its association with bone turnover markers as well as body composition parameters in adult patients with different types of OI.

DESIGN, SETTING, AND PARTICIPANTS

This was a case-control study in 27 adult patients and 50 healthy age- and gender-matched controls.

MAIN OUTCOME MEASURES

Serum sclerostin levels and bone turnover markers including serum osteocalcin, amino terminal propeptide of type I procollagen, and CrossLaps as well as body composition parameters were determined in mild OI stage I (OI-I) and moderate-severe OI stages III-IV (OI-III-IV), according to Sillence classification. Data were compared with healthy controls.

RESULTS

Sclerostin levels were significantly lower in OI-I (19.9 ± 10.9 pmol/L; P < .001) and OI-III-IV (13.3 ± 10.0 pmol/L; P < .001) compared with healthy adults (45.3 ± 14.9 pmol/L), even after adjustment for age, sex, bone mineral content, and body mass index. CrossLaps and PTH were significantly lower in OI-I (0.197 ± 0.15 ng/L; P = .007 and 33.7 ± 19.1 pg/L; P = .033, respectively) and OI-III-IV (0.221 ± 0.18 ng/L; P = .039, and 27.9 ± 14.7 pg/L; P = .001, respectively) than in healthy controls (0.322 ± 0.15 ng/L and 45.0 ± 16.6 pg/L). Amino-terminal propeptide of type I procollagen was below the reference range for OI-I and OI-III-IV. Patients with OI were shorter and lighter and had a decreased bone mineral content (P < .001) but similar fat distribution and lean body mass, compared with controls. Serum sclerostin levels were not related to any bone marker except osteocalcin, the number of prevalent fractures, or body composition readings.

CONCLUSION

Decreased sclerostin levels in OI might reflect a down-regulation or negative feedback mechanism to prevent further bone loss.

Teriparatide treatment in adult patients with osteogenesis imperfecta type I

Osteogenesis imperfecta (OI) is a hereditary disease characterized by low bone mass, increased bone fragility, short stature, and skeletal deformities. This study focuses on OI type I, the mildest form of the disease. Bisphosphonates represent the prevailing standard of care in patients with OI. Teriparatide (TPD) is a PTH analog with bone-anabolic actions which has been approved for osteoporosis treatment. Thirteen postmenopausal women with type I OI who had been on treatment with neridronate for at least 2 years and who incurred new vertebral fracture during treatment were treated with TPD for 18 months. Bone mineral density (BMD) increased significantly over 18 months up to 3.5 % at the lumbar spine (p = 0.001), while no significant changes were noted in hip BMD. Serum markers of bone formation and of bone resorption increased significantly during the treatment. The Wnt inhibitors serum dickkopf-1 (DKK1) and sclerostin were also measured. A nonsignificant increase was seen in serum sclerostin levels, while serum DKK1 rose gradually and significantly during TPD treatment. In patients affected by type I OI, TPD treatment is associated with a remarkable response in markers of bone formation. This suggests a normal osteoblastic response to TPD. However, the observed increases in BMD were somewhat lower than those in postmenopausal or senile osteoporosis treated with TPD for the same lag time. Our results open the possibility to develop TPD for the treatment of adult type I OI, but particularly for the lack of a control group, a properly designed controlled study is warranted.

Sickle cell disease with osteogenesis imperfecta

A 16 yr old female presented with generalized weakness and easy fatigability since 2 months. Her medical history included that she had sickle cell disease (ss pattern) on regular treatment. She denied smoking and consumption of alcohol. She had adequate calcium intake and her menstrual history was non-contributory. History of right tibial diaphysial fracture 1 year back followed by refracture at the same site 6 months later. On examination patient was 146 cm tall & weighed 48 kg. She had pallor, blue-grey sclera,scar mark of previous operation on right leg. Her mother and two maternal aunts also had blue-gray sclera. She had normal dentition and other systems were normal. Radiological screening showed diffuse osteopenia of all visualized skeleton, biconcave vertebral bodies in lumbar spine, Old healed fracture of right tibial diaphysis with intra-medullary nail in situ, wormian bones seen along the lambdoid suture, old healed fracture with sclerosis noted involving diaphysis of first metatarsal. Secondary causes of osteoporosis were ruled out. Skeletal involvement is sickle cell disease is usually in the form of avascular necrosis, dactylitis, joint effusions or osteomyelitis however osteoporosis and long bone fractures are not known in sickle cell disease. Owing to high index of suspicion a diagnosis of osteogenesis imperfecta was pursued, since the patient presented at 16 years age with relatively minor symptoms type 1A osteogenesis imperfecta (mildest form) was established. Systemic screening for disease complications included osteopontogram, audiogram and consultation with ophthalmologist and geneticist. Therapy with calcium and vit D was initiated and an in depth discussion regarding biphosphonates was pursued. Anaemia was corrected with blood transfusion and treatment of sickle cell disease was continued. Family screening was offered. Fractures particularly adults older than 45 are associated with osteoporosis. This case illustrates the importance of family history, fracture history and clinical correlation when assessing patients with osteoporosis. Mild OI most often presents after infancy and should be considered whenever children or adults have recurrent fractures. Early diagnosis of this disease by family physicians will enable initiation of therapy as well as patients education regarding management of modifiable risk factors linked with osteoporosis (e.g. diet, smoking, alcohol). Genetic counseling and family screening could also be offered.

Sclerostin antibody improves skeletal parameters in a Brtl/+ mouse model of osteogenesis imperfecta

Osteogenesis imperfecta (OI) is a genetic bone dysplasia characterized by osteopenia and easy susceptibility to fracture. Symptoms are most prominent during childhood. Although antiresorptive bisphosphonates have been widely used to treat pediatric OI, controlled trials show improved vertebral parameters but equivocal effects on long-bone fracture rates. New treatments for OI are needed to increase bone mass throughout the skeleton. Sclerostin antibody (Scl-Ab) therapy is potently anabolic in the skeleton by stimulating osteoblasts via the canonical wnt signaling pathway, and may be beneficial for treating OI. In this study, Scl-Ab therapy was investigated in mice heterozygous for a typical OI-causing Gly→Cys substitution in col1a1. Two weeks of Scl-Ab successfully stimulated osteoblast bone formation in a knock-in model for moderately severe OI (Brtl/+) and in WT mice, leading to improved bone mass and reduced long-bone fragility. Image-guided nanoindentation revealed no alteration in local tissue mineralization dynamics with Scl-Ab. These results contrast with previous findings of antiresorptive efficacy in OI both in mechanism and potency of effects on fragility. In conclusion, short-term Scl-Ab was successfully anabolic in osteoblasts harboring a typical OI-causing collagen mutation and represents a potential new therapy to improve bone mass and reduce fractures in pediatric OI.

[Screening of bone-related microRNAs in serum of patients with osteogenesis imperfect]

We screened differential expression bone-related microRNAs (miRNAs) in serum of patients with osteogenesis imperfect (OI). First, we selected the reference gene (s) fit for quantitative detection of serum miRNAs by using geNorm and several other programmes. Then real-time fluorescent quntitative PCR was used to detect the expression level of bone-related miRNAs gained by means of miRanda, Targetscan and Pictar softwares caculation and reading literature. Then, the results were analyzed with the matched t test. All 6 candidate reference genes had a stable expression level in serum of healthy controls and patients with different characters, and the optimal number of reference genes is 4 (miR-16, let-7a, snRNAU6, miR-92a) after Pairwise Variations analysis (V4/5 = 0.133 < 0.15). For validating the universality of expression stability, we detected the relative expression value of miR-16, let-7a, snRNAU6 and miR-92a in another 8 healthy controls and 16 patients with OI and the result revealed that the expression of 4 genes remained stable (M < 1.5). After measuring serum levels of more than 100 bone-related miRNAs in patients with real-time qPCR, 11 miRNAs showed differential expression, and bioinformatic analysis suggested these altered expressional mioRNAs had possibilities to participate in the process of OI. So the experiment indicated that there existed many differential expression bone-related miRNAs in serum of patients with OI, and these miRNAs had potentials to be promising biomarkers for serologic tests and diagnosis of OI.

Lack of circulating pigment epithelium-derived factor is a marker of osteogenesis imperfecta type VI

BACKGROUND

Osteogenesis imperfecta (OI) type VI is a rare autosomal recessive bone fragility disorder that is caused by inactivating mutations in SERPINF1, the gene that encodes pigment-epithelium derived factor (PEDF). Determining PEDF serum levels might facilitate the diagnosis of OI type VI.

OBJECTIVE

The objective of the study was to assess whether lack of circulating PEDF is a specific marker of OI type VI and to evaluate whether PEDF serum levels are influenced by other metabolic bone diseases.

MATERIALS AND METHODS

Serum PEDF concentrations were measured in 12 patients with OI type VI (aged 2.7-31 yr) as well as in 96 children and adolescents with OI types I, III, and IV; in 26 young patients with hypophosphatemic rickets; and in 19 healthy controls.

RESULTS

Circulating PEDF was undetectable in all 12 patients with OI type VI but was measurable for the other 141 study participants. No significant differences in serum PEDF concentrations were found between the diagnostic groups other than OI type VI. Treatment with bisphosphonates (in OI types I, III, and IV) and with phosphate and calcitriol (in hypophosphatemic rickets) did not have a detectable influence on serum PEDF. In patients with OI types I, III, and IV, serum creatinine, body mass index z-score, and OI severity were significant predictors of PEDF serum levels.

CONCLUSION

Determining PEDF serum concentration helps to diagnose OI type VI but does not seem to provide information on the activity of bone turnover or mineralization.

Serum 24,25-dihydroxyvitamin D concentrations in osteogenesis imperfecta: relationship to bone parameters

BACKGROUND

Several studies suggest that 24,25-dihydroxyvitamin D [24,25(OH)₂D] may have an effect on bone mass and metabolism.

OBJECTIVE

We evaluated the relationship between serum 24,25(OH)₂D levels and bone density and bone metabolism in children with a primary bone disorder-osteogenesis imperfecta (OI).

MATERIALS AND METHODS

The study included 132 patients (age, 1.1 to 17.9 yr; 67 girls) with OI types I, III, or IV who had not received bisphosphonate treatment at the time of analysis.

RESULTS

Serum 24,25(OH)₂D levels were significantly higher in OI type III than in OI type I or IV. Serum 24,25(OH)₂D concentrations were positively correlated with serum 25-hydroxyvitamin D (25OHD) levels and negatively correlated with serum PTH levels, and were not correlated with serum 1α,25-dihydroxyvitamin D [1,25(OH)₂D]. The ratio between serum 24,25(OH)₂D and 25OHD was negatively correlated with age and was independent of serum 25OHD concentrations. Regression analysis revealed that OI severity (P = 0.04), serum 25OHD levels (P < 0.001), and serum PTH concentrations (P = 0.045), but not age, gender, or serum 1,25(OH)₂D, were independent predictors of serum 24,25(OH)₂D levels. No correlation was found between serum 24,25(OH)₂D levels or the ratio between serum 24,25(OH)₂D and 25OHD and lumbar spine bone mineral density z-scores or bone marker levels (serum osteocalcin and urinary collagen type I N-telopeptide) after adjusting for OI type, age, and gender.

CONCLUSION

Patients with more severe OI type had higher 24,25(OH)₂D serum levels and higher serum 24,25(OH)₂D to 25OHD ratios, suggesting an increased 25OHD-24-hydroxylase activity.

[Brittle bone disease type III in neonates--own experience]

Fractures of long bone and ribs in the neonatal period may be expression of genetic disturbances of collagen type I production. The aim of the study was to present clinical symptoms, results of radiological, biochemical and densitometric examinations in 11 newborns with osteogenesis imperfecta type III.

METHODS

In all children accurate medical history, clinical examination and radiograph were performed. We measured concentration of 25-hydroxyvitamin D (25OHD) and osteocalcin (bone formation marker) in serum. Urinary excretion of bone resorption marker type I collagen N-telopeptide related to creatinine were made. In 5/11 children densitometric examination in Infant programme by DXA method (dual-X-ray absorptiometry) were done.

RESULTS

In all family osteogenesis imperfecta occurred by the first. In clinical examination deformities in body proportion, shortness of the extremities, sabre shanks, flabbily of skull bones and reduction of activity were diagnosed. 8/11 newborns had blue sclera. In all X-ray (baby-gram) bone fractures occurring in utero as well as after birth were founded. In biochemical indices a small numbers of abnormality were described. In 5/11 newborns with results of densitometric examination normal bone mineral density adequate to body mass were demonstrated, in 3/5 bone mineral content (BMC) were decreased.

CONCLUSION

1.Osteogens esis imperfecta is the one of reasons of bone fractures in neonates and its diagnosis is based on family history, clinical manifestation and X-ray examination. 2. In newborns with bone fractures dual X-ray absorptiometry are recomendated.

Proteomic analysis of plasma profiles in children with recurrent bone fractures

The aim of the study is proteomic analysis of the plasma profile in children with recurrent bone fractures. The study involved 16 children: 6 patients with recurrent low-energy fractures and normal bone mass and 10 with osteogenesis imperfecta. In the analysis of the protein profile, the two-dimensional protein electrophoresis was used (Ettan DALT II, Amersham Bioscience). The images of protein gels were compared with controls. The protein spots with changed expression were cut from the gel and the amino acid sequence was analyzed with the mass spectrometry method (Q-Tof Premier(TM) API MASS SPECTROMETR, Waters) for protein identification. The most prevalent protein with changed expression, with respect to controls, was haptoglobin observed in 6 patients with a severe form of osteogenesis imperfecta. Increased haptoglobin concentration in these patients was confirmed by the ELISA method. Peptides corresponding to alpha-1 acid glycoprotein and serum amyloid P-component, apolipoprotein A-I, and transthyretin were detected in one, two and three children, respectively.

CONCLUSIONS

1) The results show increased haptoglobin which may be suggestive of an inflammatory component taking part in the course of osteogenesis imperfecta. 2) Further studies to explain the possible relationship of this protein with increased bone fragility are necessary.

Predictors and correlates of vitamin D status in children and adolescents with osteogenesis imperfecta

BACKGROUND

The prevalence of vitamin D deficiency and its consequences on bone in pediatric bone fragility disorders is not well characterized. In the present study, we evaluated determinants of vitamin D status in children and adolescents with osteogenesis imperfecta (OI) and assessed the relationship between 25-hydroxyvitamin D (25OH D) serum concentrations and lumbar spine areal bone mineral density (LS-aBMD).

MATERIALS AND METHODS

This retrospective cross-sectional study comprised 315 patients with a diagnosis of OI type I, III, or IV (aged 1.1-17.9 yr; 161 girls) who had not received bisphosphonate treatment at the time of 25OH D analysis. In 282 patients (90%), LS-aBMD measurements were available at the same time.

RESULTS

Serum concentrations of 25OH D ranged from 14 to 133 nmol/liter and were less than 50 nmol/liter in 86 patients (27%). Regression analysis revealed that age (P < 0.001), season (P < 0.001), and OI severity (P = 0.048), but not gender, were significant independent predictive factors of 25OH D levels. Serum 25OH D concentrations were negatively correlated with serum PTH levels (P = 0.003) and urinary cross-linked N-telopeptides of type I collagen to creatinine ratios (P = 0.005). Serum 25OH D levels were positively associated (P = 0.02) with LS-aBMD z-scores after accounting for OI severity, age, and gender.

CONCLUSION

Serum 25OH D levels are positively associated with LS-aBMD z-scores in children and adolescents with OI types I, III, and IV.

Decrease in serum FGF23 levels after intravenous infusion of pamidronate in patients with osteogenesis imperfecta

Fibroblast growth factor 23 (FGF23) plays a central role in phosphate (P) homeostasis. However, the precise mechanism of how FGF23 secretion is regulated remains to be elucidated. In the present study, we examined the effect of intravenous pamidronate administration on serum levels of FGF23. Thirteen patients with osteogenesis imperfecta were treated with two cycles of 3-day pamidronate infusion. Blood samples at pre- and post-drip pamidronate infusion were evaluated for serum calcium, P, intact PTH (iPTH), 1,25(OH)(2)D, intact FGF23 (FGF23), type I collagen cross-linked N-telopeptides (NTx), bone-specific alkaline phosphatase (BAP), and TmP/GFR. During the two cycles, FGF23 levels decreased significantly preceding the decline in P levels. Although the change in P levels became less apparent during the second cycle, the reduction in FGF23 levels was similar during both cycles. Moreover, absence of correlation between FGF23 and P indicates that FGF23 attenuation is independent of the decrease in P levels during pamidronate infusion. Significant correlation between NTx suppression and the decrease in FGF23 levels during the 1st cycle (r = 0.665, P = 0.013) suggests that inhibition of osteoclast function may have some role in suppressing FGF23 levels. Because pamidronate dose was most associated with the decrease in FGF23 levels during the second cycle, pamidronate may directly attenuate osteocyte/osteoblast-mediated FGF23 production. This is the first evidence of a rapid fall in FGF23 levels following pamidronate infusion, raising the possibility that inhibition of bone resorption and/or direct effects of pamidronate may suppress secretion of FGF23.

Biochemical bone markers in the assessment and pamidronate treatment of children and adolescents with osteogenesis imperfecta

AIM

 To assess the role of biochemical bone markers in classification of children with osteogenesis imperfecta (OI), their possible association with vertebral compression fractures in milder forms of OI and their role in monitoring of intravenous pamidronate (APD) treatment.

METHODS

 Serum total alkaline phosphatase (ALP), bone ALP isoforms (in a subgroup), osteocalcin, type I procollagen carboxy-terminal propeptide, carboxy-terminal telopeptide of type I collagen, and urine deoxypyridinoline (DPD) were measured in a cross-sectional study of 130 untreated individuals, 0.25-20.9years (median 6.7), with OI types I, III and IV. Of those, sixty-nine were also assessed longitudinally during monthly APD treatment. Bone mineral density (BMD) was measured by dual-energy X-ray absorptiometry.

RESULTS

 Significant differences in bone markers, however not sufficient for individual clinical use, were found in the larger untreated group but not between subgroups with or without vertebral compressions. All bone markers decreased during treatment for 1.0-12.5years, but with different relative amounts. Changes were not correlated to the improvement in BMD, mobility or pain.

CONCLUSION

  Bone markers are, despite significant differences, not useful for the classification of OI type in the individual child and are not associated with vertebral compressions. Serum ALP and urinary DPD are sensitive in monitoring bisphosphonate treatment.

Intravenous pamidronate in osteogenesis imperfecta type VII

Cyclical intravenous treatment with pamidronate is widely used to treat osteogenesis imperfecta (OI) types I, III, and IV, which are due to dominant mutations affecting collagen type I alpha chains. There is no information about the effects of pamidronate in children with OI type VII, an autosomal-recessive form of OI caused by a mutation in the cartilage-associated protein gene. In this retrospective single-center study, we compared the effects of pamidronate in four girls with OI type VII (age range 3.9-12.7 years) to those in eight girls with OI types caused by collagen type I mutations who were matched for age and disease severity. During 3 years of pamidronate therapy, lumbar spine areal bone mineral density increased and lumbar vertebral bodies improved in shape in patients with OI type VII. Other outcomes such as fracture rates and mobility scores did not show statistically significant changes in this small study cohort. There were no significant side effects noted during the time of follow-up. Thus, intravenous treatment with pamidronate seems to be safe and of some benefit in patients with OI type VII.

Reduction of plasma taurine level in children affected by Osteogenesis Imperfecta during bisphosphonate therapy

Osteogenesis imperfecta (OI) is a heritable disease of connective tissue characterized by increased bone fragility. To date, bisphosphonates seem to be the most promising therapy, at least for children. In the last decade experimental and clinical studies indicate that several amino acids are implicated in bone mineralization. Particularly, taurine is localized in matrices of the bone and can regulate osteoblast metabolism with antiosteopenic effect. To investigate a possible interaction between pharmacological effects of bisphosphonates and amino acids involved in bone metabolism, we performed plasma and urine amino acids analysis in children affected by OI before and during treatment with bisphosphonates. Fourteen prepubertal children with moderate to severe types of OI, 8 males and 6 females, aged from 2 to 11 years (mean (SD) 6.9+/-2.53) were enrolled in the study. Patients were treated with neridronate infusion (1mg/kg/body weight) every three months. Plasma and urine specimens for amino acid analysis were kept at baseline (T0) and three months after each infusion of four consecutive cycles (T1-T4). A significant decrease in respect to the pre-treatment levels (T0) was observed after the fourth infusion for taurine (p<0.01). In addition, urinary excretion of this amino acid showed a significant decrease after the fourth infusion. No significant correlations were found between plasma level or urinary excretion of hydroxyproline, taurine, arginine and lysine in respect to bone mineral density. The progressive reduction of plasma taurine found in our patients treated with bisphosphonates could be implicated in the action mechanism of this drug in OI and possibly in other disorders of bone metabolism. This knowledge could provide new opportunities to improve treatment with bisphosphonates and address novel strategies for the therapeutic approach to bone disorders.

Heterozygous mutations in the LDL receptor-related protein 5 (LRP5) gene are associated with primary osteoporosis in children

Three of 20 patients with juvenile osteoporosis were found to have a heterozygous mutation in the LRP5 gene. No mutations were found in the type I collagen genes. Mutations in the other family members with similar bone phenotype confirmed that LRP5 has a role in both juvenile and adult osteoporosis.

INTRODUCTION

The gene encoding the low-density lipoprotein receptor-related protein 5 (LRP5) gene has recently been shown to affect bone mass accrual during growth and to be involved in osteoporosis-pseudoglioma syndrome and a high bone mass phenotype. Mutations in the type I collagen genes (COL1A1 and COL1A2) are known to cause osteogenesis imperfecta, characterized by increased bone fragility.

MATERIALS AND METHODS

Here we analyzed COL1A1, COL1A2, and LRP5 for mutations in 20 pediatric patients with primary osteoporosis characterized by low BMD, recurrent fractures, and absent extraskeletal manifestations.

RESULTS AND CONCLUSIONS

No mutations were detected in the type I collagen genes, but two missense mutations (A29T and R1036Q) and one frameshift mutation (C913fs) were found in the LRP5 gene in three of the patients. The frameshift mutation was also seen in the proband's father and brother, who both were found to have significant osteoporosis. R1036Q was observed in the proband's mother and two brothers, who all had osteoporosis. These results indicate that heterozygous mutations in the LRP5 gene can cause osteoporosis in both children and adults.

Intravenous pamidronate treatment of children under 36 months of age with osteogenesis imperfecta

INTRODUCTION

Bone mineral density (BMD) and fracture rates in children with osteogenesis imperfecta (OI) have been shown to improve with bisphosphonate therapy. There are limited data available on the efficacy of this therapy in children with OI under the age of 3 years. To examine this, we instituted a prospective clinical trial of intravenous bisphosphonate to study safety, feasibility, and efficacy of this therapy.

MATERIALS AND METHODS

Nine infants and young children with osteogenesis imperfecta (age range 1-35 months) were treated with intravenous pamidronate. Six had type II OI, two had type I, and one had type IV. Pamidronate was administered in cycles of 3 consecutive days. The total duration of therapy ranged from 11 to 29 months (mean 17 months).

RESULTS

During treatment, the mean annualized percent change in total body areal BMD was 25% (range 11-40%). Pamidronate therapy resulted in sustained and significant decreases in serum calcium and bone-specific alkaline phosphatase and in urine calcium/creatinine and NTX/creatinine. Fracture rate in the group decreased from 80 fractures in 111 months before treatment to 25 fractures in 152 months after treatment (P<0.01). Linear growth and weight gain were maintained. Other than fevers in several infants following the initial dose of intravenous bisphosphonate no adverse effects of therapy were noted.

CONCLUSIONS

Our data support that intravenous pamidronate therapy is safe, increases BMD, and reduces fracture rates in very young children with OI. Currently, it would seem to be the best available treatment for these children.

Bone turnover markers in patients with osteogenesis imperfecta

Osteogenesis imperfecta (OI) is a heterologous group of rare inherited bone disorders resulting from defect in collagen synthesis or function. In previous studies, bone turnover has been found either increased or low-normal. These contradictory results might result from the study population made of children with prior recent fractures. We measured serum total and bone alkaline phosphatase (total and bone AP) serum osteocalcin (sOC), serum type I collagen C-telopeptide breakdown products (sCTX), urinary free-deoxypyridinoline (ufDPD), and urinary cross-linked N-telopeptides of type I collagen (uNTX) in 39 male and 38 premenopausal patients with different types of OI aged between 18 and 51 years who had not experienced new clinical fracture during 12 months preceding the laboratory assessment. The study also includes a control group of 29 men and 26 women matched for age and gender. Most bone markers were 50-200% higher in patients than in controls. Only sCTX was comparable to that found in controls. From a sub-analysis of the data, a trend for higher bone resorption markers was observed for any OI type, but patients with OI type III and IV had significantly higher values in ufDPD and uNTX than patients with type I OI, and their sOC levels were not significantly higher than in controls. These results provide a strong rational for the use of anti-resorbing agent in OI.

Intravenous pamidronate treatment in children with moderate to severe osteogenesis imperfecta: assessment of indices of dual-energy X-ray absorptiometry and bone metabolic markers during the first year of therapy

Bisphosphonates are now widely used to treat children with osteogenesis imperfecta (OI). However, there are few published data following the initial evolution of changes in bone mass with such treatment. The purpose of the present study was to assess indices of skeletal size and total and regional bone mass in children with OI during the first year of their pamidronate therapy. Twenty-six children [11 males, age median 10.6 (range 3.2-15.5) years] with type III (n=9) or type IV (n=17) OI received intravenous pamidronate 1.0 mg/kg/day on 3 consecutive days, 3-monthly over a 1-year period. Bone mass assessed by dual energy X-ray absorptiometry, serum alkaline phosphatase (ALP) and urine type I collagen N-terminal telopepetide (NTX) were measured at each cycle. Lumbar (L2 to L4) vertebral height increased by median (interquartile range) 4.5% (7.3), area by 11.3% (19.3), bone mineral content (BMC) by 73.7% (50.4), and bone mineral density (BMD) by 48.7% (34.7), P<0.0001 during the first year of therapy. Total body bone area increased by 26.7% (26.3), total body BMC by 41.4% (44.5), and total body BMD by 8.8% (8.3), P<0.0001. Head bone area remained constant whilst head BMC and BMD increased. Pre-infusion U-NTX and S-ALP levels decreased progressively during the follow-up indicating reducing bone turnover rate during pamidronate therapy. Increased bone area and mineral mass were observed during the first year of intravenous pamidronate therapy in children with OI. Increased head bone mass implies a direct effect of pamidronate on skeletal mass accretion, rather than an indirect effect mediated through increased physical activity.

Beneficial effect of long term intravenous bisphosphonate treatment of osteogenesis imperfecta

AIM

To find an effective symptomatic treatment for osteogenesis imperfecta (OI).

METHODS

In a prospective observational study disodium pamidronate (APD) was given as monthly intravenous infusions to 28 children and adolescents (aged 0.6-18 years) with severe OI or a milder form of the disease, but with spinal compression fractures.

RESULTS

During treatment for 2-9 years, dual energy x ray absorptiometry measurements of the total body and of the lumbar spine showed a gradual increase in bone density. All bone metabolism variables in serum (alkaline phosphatase, osteocalcin, procollagen 1 C-terminal peptide, collagen 1 teleopeptide) and urine (deoxypyridinoline) indicated that there was a decrease in bone turnover. All patients experienced beneficial effects and the younger patients reported a major improvement in wellbeing, pain, and mobility without significant side effects. Vertebral remodelling was also seen.

CONCLUSIONS

APD seems to be an efficient symptomatic treatment for children and adolescents with OI.

Increased bone resorption with decreased activity and increased recruitment of osteoblasts in osteogenesis imperfecta type I

An iliac bone biopsy from an adult male, 58 years of age, with osteogenesis imperfecta type I was studied by bone histomorphometry after double-fluorescence labeling with tetracycline. Low bone mineral density (BMD) of the radius, measured by dual-energy X-ray absorptiometry (DXA) was associated with high levels of urinary deoxypyridinoline and serum bone-specific alkaline phosphatase and osteocalcin. At the tissue level, low cancellous bone volume (BV/TV) was associated with increased eroded surface (ES/BS) and a relatively increased osteoclast number (N.Oc/BS). Osteoid thickness (O.Th) was also decreased as a result of decreased bone matrix synthesis, in terms of decreased osteoblastic activity. However, osteoid surface (OS/BS) and osteoblast surface (ObS/BS), in terms of the number of osteoblasts, were increased. We conclude that the patient showed cancellous osteopenia, which was likely due to increased bone resorption with decreased activity and increased recruitment of osteoblasts.

Cyclic pamidronate infusion improves bone mineralisation and reduces fracture incidence in osteogenesis imperfecta

A prospective open study was performed to determine the efficacy and safety of pamidronate in improving bone mineralisation and reducing fracture incidence in osteogenesis imperfecta (OI). Intravenous pamidronate was administered at 1.5 mg/kg bi-monthly to six children with OI, over 12-23 months. The number of fractures decreased from median of 3 (range 1-12) to 0 fractures/year (range 0-4) (P<0.05). After 12 months of treatment, there was significant improvement in areal bone mineral density (BMD) z-scores of the lumbar spine from median of -2.40 (range -3.20 to -1.67) to -1.90 (range -2.38 to -0.91) (P<0.05) and in the volumetric BMD which increased from median of 0.095 to 0.146 g/cm3 (P<0.05). Urine N-telopeptide levels (bone resorption marker) decreased from a median of 461.5 bone collagen equivalent/creatinine (BCE/Cr) (range 129-721 BCE/Cr) to 223.5 BCE/Cr (range 107-312 BCE/Cr) (P<0.05) and serum alkaline phosphatase (ALP) (bone formation marker) from a median of 230.0 U/l (range 148-305 U/l) to 133.5 U/l (range 79-233 U/l) (P<0.05), reflecting reduced bone turnover. This may represent a net reduction in bone resorption and provides a biochemical explanation for the increase in bone mineralisation. Height standard deviation scores were not affected and there were no significant adverse effects.

CONCLUSION

1 year cyclical pamidronate is effective and safe in improving bone mineralisation and reducing fracture incidence in osteogenesis imperfecta.

Anaemia, osteogenesis imperfecta and valve diseases. The preoperative treatment with epoetin-alpha to increase haematocrit and haemoglobin levels in patients with high risk of perioperative bleeding

The case of a patient with Osteogenesis imperfecta is reported who underwent surgery for mitral valve replacement. Osteogenesis imperfecta is a hereditary disease of the connective tissue, associated with bone fragility, bluish colouring of the sclerae, loss of hearing and dental anomalies. Osteogenesis imperfecta is included in a group of hereditary pathologies with Ehlers-Danlos syndrome, Hurler syndrome, pseudoxanthoma elasticum and Marfan syndrome. In the literature there are few cases of patients with osteogenesis imperfecta operated for mitral valve disease secondary to such disease. The patient also has a positive family history and a severe anaemia: this was treated with epoetin-alpha and ferrous sulphate during the three weeks before surgery. The response to epoietin treatment was good while clinical outcome was poor due to rupture of the posterior ventricular wall in the 12th postoperative hour. The use of epoietin-alpha is discussed.

Osteogenesis imperfecta: bone turnover, bone density, and ultrasound parameters

We studied 21 patients (11 men and 10 women) with osteogenesis imperfecta (OI) and 21 age- and sex-matched controls. In all patients we measured serum levels of total alkaline phosphatase (ALP), type I procollagen carboxy-terminal propeptide (PICP), osteocalcin (BGP), urinary excretion of hydroxyproline (HOP/Cr), and pyridinoline crosslinks (Pyr/Cr). Bone mineral density was measured at the distal radius (BMD-R) and at the lumbar spine (BMD-LS) by dual X-ray absorptiometry (DXA). Ultrasound parameters were also performed at the calcaneous with the Achilles device and at the phalanxes with DBM Sonic 1200. A significant reduction (P < 0.001) in BMD and in ultrasound parameters was found in OI patients compared with normals. PICP was significantly reduced in the OI patients compared with controls (P < 0.001); other markers of bone turnover were higher in OI than in controls, but the difference did not reach the statistical significance. A significant correlation (P < 0.05) was found between PICP and BMD at the lumbar spine and between PICP and ultrasound parameters at the calcaneous. On the basis of our data, we conclude that patients with OI show low values of BMD and ultrasound parameters; therefore in these patients, not only is bone mass disturbed but also bone quality. The reduced levels of PICP in OI patients confirm that most OI patients have defects in collagen I biosynthesis. These defects may contribute to the fragility of OI bone by interfering with complete mineralization and/or normal tissue structure. PICP may be considered a useful marker in the clinical management of OI.

Anthropometry of patients with osteogenesis imperfecta

Standing height, sitting height, armspan, subischial leg length, head circumference, and growth hormone-insulin-like growth factor I (IGF-I) axis were determined in 86 patients with osteogenesis imperfecta. The aim of this study was to determine standing height and body proportions and their variability among osteogenesis imperfecta types and collagen defects. Mean standing height was reduced in all groups of patients, to the greatest extent and variability in osteogenesis imperfecta type III/IV and in those with qualitative collagen defects. The mean standing height of patients with osteogenesis imperfecta was lower than that of their unaffected first degree family members. Truncal height of patients with osteogenesis imperfecta was reduced; head size was increased, and this was more pronounced in patients with osteogenesis imperfecta type III/IV and qualitative collagen defects than in patients with osteogenesis imperfecta type I and quantitative collagen defects. Mean concentrations of IGF-I and IGF binding protein 3 (IGFBP-3) were low, but most values were within age specific reference values. The reduction of standing height appears to correlate with osteogenesis imperfecta type and the type of collagen defect. A relatively short trunk is typical and head circumference and body length are disproportionate.

Reduced serum levels of carboxy-terminal propeptide of human type I procollagen in a family with type I-A osteogenesis imperfecta

We measured serum levels of total alkaline phosphatase activity, osteocalcin, carboxy-terminal propeptide of human type I procollagen (PICP), tartrate-resistant acid phosphatase activity (TRAP), and the fasting urinary hydroxyproline/creatinine ratio (OHPr/Cr) in seven affected members (four men, three women; age, 43.3 +/- 16.6 years [mean +/- SD]) of a family with clinically diagnosed type I-A osteogenesis imperfecta (OI) and in eight (five men, three women) normal age-matched (38.2 +/- 10.3) relatives. Three boys with OI and three normal girls of the same family were also studied, although they were excluded from statistical analysis. Bone mineral density was also determined at four different skeletal sites. Serum levels of PICP were measured with a radioimmunoassay (Farmos Diagnostica, Turku, Finland). There were no significant differences in mean values of the biomarkers studied between OI patients and normal relatives, with the only exception being serum levels of PICP (35 +/- 7.5 v 219 +/- 107.5 micrograms/L, P < .001). A significant reduction of BMD was found in OI patients compared with normal relatives at the lumbar (L) spine (680 +/- 61 v 1,128 +/- 92 mg/cm2, P < .001), at the ultradistal radius ([UDR] 323 +/- 85 v 458 +/- 76, P < .006), at the femoral neck ([F] 494 +/- 140 v 791 +/- 104, P < .001), and at the junction of the distal and middle third of the radius ([MR] 639 +/- 71 v 717 +/- 52, P < .029).(ABSTRACT TRUNCATED AT 250 WORDS)

The growth hormone and somatomedin axis in short children with osteogenesis imperfecta

Growth deficiency is a cardinal feature of severe osteogenesis imperfecta (OI) and a frequent feature of mild to moderate forms of this disease. We have investigated the status of hormones related to growth in 22 short prepubertal children, 13 males and 9 females, with various types of OI. Ten children had Sillence type III OI, 10 had type IV, and 2 had type I. Evaluation included GRH stimulation, three standard GH provocative tests (arginine-insulin tolerance test, L-dopa), 24-h sampling for measurement of unstimulated GH secretion and a somatomedin-C generation test. None of these children had GH deficiency by standard criteria. We found that 9 OI children had decreased responsiveness to GRH, similar to the GRH response of GH-deficient children. Overall, however, mean 24-h GH values and mean peak GH response to provocative agents of OI children were within the normal range. In the somatomedin generation test, the OI children as a group showed a blunted response, with 13 of 22 having less than a 2-fold stimulation of somatomedin-C by GH. This suggested resistance of the liver and other somatomedin-C secreting tissues to GH. The group with blunted insulin-like growth factor-I response did not correlate significantly with the group with decreased GRH response. To investigate the responsiveness of OI bone to growth stimulation, six OI children with less than average integrated GH secretion were enrolled in a pilot study in which one child received exogenous GH and six received clonidine for at least 6 months. The child treated with exogenous GH and three of six treated with clonidine experienced at least a 4.7 cm/yr increase over their pretreatment growth rates. Growth response could not be predicted from baseline studies. We conclude that abnormalities of the GH-somatomedin axis exist in some children with OI. Administration of GH or clonidine may augment growth rates in OI children; however, the effect of these agents on final stature is unknown.

Influence of age, sex and osteogenesis imperfecta on count, protein content, and monoamine oxidase activity of human thrombocytes

We determined the effect of count, age (2 to 24 year), sex, and osteogenesis imperfecta (OI) on the protein content and monoamine oxidase activity in human platelets. The reaction rate in presence of paramethoxybenzylamine was assessed in a sensitive and continuously recording spectrophotometric system. Platelets harvested from control subjects and OI patients displayed significant inverse linear correlations between count and protein content; there was near-constancy of the products of the two variables. The effects of age, sex, and osteogenesis imperfecta on protein content, count, and MAO activity were assessed by multivariate analysis of variance. It was found that, with increasing age, the count increased linearly and the protein content decreased. In patients with OI the protein content was depressed and monoamine oxidase activity elevated regardless of whether the latter was calculated on the basis of pellet protein or of count. The data suggest that, in osteogenesis imperfecta, thrombocytic monoamine and protein metabolism deviate from that of controls.

Serum calcitonin and bone mineral content in patients with osteogenesis imperfecta

Serum calcitonin and bone mineral content in the forearm, measured by photon absorptiometry, were investigated in 21 patients with osteogenesis imperfecta tarda. The bone mineral content was significantly reduced as compared with normal controls, whereas the bone mineral content corrected for bone width was normal in adult patients but subnormal in children and young adults. Serum calcitonin did not differ significantly from that in normal individuals and no relation was found between serum calcitonin and bone mineral content.

The co-existence of primary hyperparathyroidism and osteogenesis imperfecta

A 47-year-old patient suffering from osteogenesis imperfecta was found to have mild hypercalcemia. The latter proved to be due to a parathyroid adenoma. The clinical and laboratory features of this association are summarized, and the implications of serum calcium abnormalities in osteogenesis imperfecta are discussed.