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ED-A region-containing isoform of cellular fibronectin is present in dentin matrix in dentinogenesis imperfecta associated with osteogenesis imperfecta.

To elucidate the defective dentin formation in osteogenesis imperfecta (OI), we analyzed the expression of selected fibronectin (FN) isoforms in the dentin matrix of a patient with dentinogenesis imperfecta (DI) associated with OI, and in normal teeth. Frozen tooth sections were immunostained with three monoclonal antibodies (MAbs). The MAb recognizing the major cell-binding region (f-33), shared by plasma FN (pFN) and cellular FN (cFN), stained the pulp of normal adult permanent teeth intensely, while no reactivity was present in predentin, (demineralized) dentin, or dental cementum. The periodontal ligament stained unevenly. The dentin matrix of the patient with OI displayed reactive zones, alternating layerwise or concentrically with non-reactive ones. Staining throughout the connective tissue of adult oral mucosa, analyzed for the form of FN present, was intense, and in dermis, which was also studied, it was moderate. Reactivities in dental tissues with the MAb specific for the ED-A region (IST-9), included in cFN but not pFN, were similar to those with MAb f-33. The mucosal connective tissue stained weakly and dermis was negative, except that nerves and endothelia of some large blood vessels stained clearly. The MAb specific for the ED-B segment (BC-1), also included in cFN only, did not stain any of the tissues analyzed. The results suggest that, unlike mucosal and dermal FNs, FNs in the dental tissues are largely cellular, and also that dentin formation in OI may be completed by successive generations of pulpal fibroblasts differentiated into hard-tissue-forming cells.

Adult↗

Osteonectin, bone proteoglycan, and phosphophoryn defects in a form of bovine osteogenesis imperfecta.

Bovine osteogenesis imperfecta is a congenital disease in Holstein cattle having several characteristics in common with human osteogenesis imperfecta syndromes. In particular, affected calves have multiple bone fractures and friable teeth. Bone collagen isolated from the affected animals (Texas variant) showed slightly decreased alpha 1(I) and alpha 2(I) chain electrophoretic mobility and increased hydroxylysine content. Overall collagen was present in the affected bones at 80-90% of normal values. However, osteonectin, a 32,000 Mr bone-specific protein found previously to promote collagen mineralization in vitro and present in abundance (approximately equal to 3% of total protein) in normal calf bone, was severely depleted (less than 2% of normal levels) in the osteogenesis imperfecta bone and dentin. The bone proteoglycan was similarly depleted. In contrast, the bone sialoprotein was not as severely affected. Further, the diseased teeth lacked (less than 10% of normal values) phosphophoryn, a dentin-specific protein normally present as 4-5% of the total calf dentin matrix. The data suggest multiple hard tissue matrix protein deletions, perhaps due to impaired cell development.

Amino Acids↗

Deficiency of cartilage-associated protein in recessive lethal osteogenesis imperfecta.

Classic osteogenesis imperfecta, an autosomal dominant disorder associated with osteoporosis and bone fragility, is caused by mutations in the genes for type I collagen. A recessive form of the disorder has long been suspected. Since the loss of cartilage-associated protein (CRTAP), which is required for post-translational prolyl 3-hydroxylation of collagen, causes severe osteoporosis in mice, we investigated whether CRTAP deficiency is associated with recessive osteogenesis imperfecta. Three of 10 children with lethal or severe osteogenesis imperfecta, who did not have a primary collagen defect yet had excess post-translational modification of collagen, were found to have a recessive condition resulting in CRTAP deficiency, suggesting that prolyl 3-hydroxylation of type I collagen is important for bone formation.

Collagen Type I↗

Ocular findings in osteogenesis imperfecta congenita.

Osteogenesis imperfecta is a rare, inherited, connective-tissue disorder. The three main signs of this disease are multiple bone fractures, blue scleras, and deafness (osteosclerotic type). In our research, only a few reports of the morphologic studies of the eyes of patients with osteogenesis imperfecta were found. This report describes the ocular histopathologic condition of four cases of osteogenesis imperfecta congenita, with emphasis on the ultrastructural characteristics of the collagen in the cornea and sclera.

Cornea↗

Dentine is biochemically abnormal in osteogenesis imperfecta.

In osteogenesis imperfecta the bones are brittle but the teeth, whose dentine contains the same genetic collagen as bone (type I), may be clinically normal. To investigate this paradox we have measured the amino acid composition of insoluble dentine collagen from 16 deciduous and 18 permanent teeth in control subjects and in 59 patients with different forms of osteogenesis imperfecta. In 55 of the patient samples significant differences from normal were found, especially in the number of lysine residues, and in the relative amounts of hydroxylysine to lysine. These results demonstrate the high frequency of biochemical abnormalities in osteogenesis imperfecta. They also suggest that classifications of this disorder based on the presence or absence of clinical dentiogenesis imperfecta are likely to be unsound.

Amino Acids↗

[Bone mineral density in children with osteogenesis imperfecta].

OBJECT: Osteogenesis imperfecta is the term used for a group of disorders of collagen synthesis which cause increased bone fragility. The aim of our study was to evaluate the BMD in patients with OI. MATERIAL AND METHODS: We used dual-energy x ray absorptiometry, Hologic QDR 4500W (DEXA), to compare the bone mineral density (BMD) of 8 patients aged from 3 years to 20 years who had osteogenesis imperfecta with an age and sex matched control group. RESULTS: DEXA detected highly significant differences in BMD respecting control group. The mean BMD in the patients with osteogenesis imperfecta was 62.6 % of normal in lumbar spine (p < 0.01) and 63.01 % of normal in the femoral neck (p < 0.01) using Wilcoxon test. CONCLUSION: DEXA is an objective, reproductible and sensitive method of measurement of BMD in children. It may help to stablish the diagnosis, to asses prognosis and possibly to monitor the response to different types of treatment.

Absorptiometry, Photon↗

Hearing loss in children with osteogenesis imperfecta.

UNLABELLED: Osteogenesis imperfecta (OI) is a genetic disorder of connective tissue. Progressive hearing loss is one of the principal symptoms of OI, affecting about 50% of adult patients. Hearing loss may also occur in childhood and results in additional disability in education and psychosocial adaptation and aggravates the physical handicap. This can be avoided by appropriate otological and audiological treatment. In a nationwide search, 254 Finnish patients with OI were identified indicating a prevalence of 4.9/100,000. Of the 60 children, 45 aged between 4 and 16 years accepting to participate the study on hearing, were evaluated by a questionnaire and clinical audiometry. Hearing loss was defined as pure tone average (PTA0.5-2 kHz) more than 20 dB hearing level (HL). A clinical geneticist determined the type of OI among the 45 patients. Two sporadic OI cases with conductive hearing loss were ascertained (4.4%): An 11-year-old girl with type IV OI with a PTA0.5-2 kHz of 35/40 dB HL and a 15-year-old boy with type IV OI with a PTA0.5-2 kHz of 27/18 dB HL. In addition, a 6-year-old girl with familial OI type I had either a congenital sensorineural deafness or early progressive deafness with PTA0.5-2 kHz of 97/103 dB HL, probably of unrelated aetiology. CONCLUSION: Hearing loss in children with osteogenesis imperfecta is less frequent than generally suspected. Nevertheless, it is recommended that audiometry is performed in children with osteogenesis imperfecta even without symptoms of hearing loss at the age of 10 years, and repeated every 3 years thereafter.

Adolescent↗

Basilar impression and platybasia in osteogenesis imperfecta tarda.

Osteogenesis imperfecta, a rare, genetically transmitted disorder of bone, is known to be associated with the development of basilar impression and platybasia. These deformities of the base of the skull may cause neurosurgical abnormalities secondary to compression of the brainstem and hydrocephalus. The case is presented of a young boy with a family history of osteogenesis imperfecta tarda who suffered respiratory arrest during hospitalization. Cranial nerves and pyramidal tract signs were demonstrated. Roentgenograms showed severe basilar impression and hydrocephalus. Decompression of the brainstem and shunting were performed with improvement in the patient's neurological status. This case represents a rare by significant central nervous system complication of osteogenesis imperfecta. Early recognition and implementation of aggressive treatment are important if irreversible neurological deficits are to be avoided.

Adolescent↗

[Osteogenesis imperfecta--operative treatment on lower extremities in children with osteogenesis imperfecta].

The group of 141 children with osteogenesis imperfecta was treated in Orthopaedic Department of the University Children Hospital in Krakow, Poland. In 77 (54.6%) children from this group, we operated on lower extremities. Prophylactic operations, that were intramedullary Rush rodding, we performed in 19 cases (14 femurs and 11 tibias). Sofield-Millar procedures we performed in 58 children. We operated 321 times - there are 4 operations on average in one child. Average follow-up period was 6.7 years. We operated 473 long bones: 234 femurs and 239 tibias. We did 479 osteotomies. First operations were done at the age of 9 years on average (1.5-21 years). Further operations, 3 in each patient on average, we performed in period 37 months from one to another on tibias and 49 months on femurs. In all operated children we achieved full axis correction and their activity after operation improved. In order to assess that, we used the Bleck scale. In general, before operation, 54 (70%) children did not walk, and, in contrast, after operations 53 (69%) started walking. Operative treatment of the lower extremities in children with osteogenesis imperfecta improves their clinical physical abilities, quality of life and allows increase in activities.

Adolescent↗

Osteogenesis imperfecta 1982.

Osteogenesis imperfecta is a highly heterogeneous disorder comprising at least four major clinically discernible conditions. Clinical and genetic observations suggest further heterogeneity. Recent advances in collagen biochemistry suggest heterogeneity of clinically identical conditions and permit a tentative clinical-biochemical classification of osteogenesis imperfecta.

Bone and Bones↗

[Combined total endoprosthesis implantation in bilateral femoral neck fracture with osteogenesis imperfecta tarda].

Osteogenesis imperfecta tarda is a hereditary disease with an insufficiency of osteoblasts caused by a collagen disorder, insufficient formation of osteoid and an impediment of periosteal bone formation. This leads to increased fragility of the bones and, as a consequence, to the risk of fractures. We report a simultaneous, bilateral medial femoral neck fracture, caused by a cerebral cramp attack. The patient is 80 years old and suffers from osteogenesis imperfecta tarda and Parkinson's disease. We implanted a cemented total endoprosthesis on each side in just one operation. There were no complications in the intra- and postoperative course. A walking aid gradually increased the patient's mobility so that he could be discharged on the 21st postoperative day.

Aged↗

Efficacy of low dose schedule pamidronate infusion in children with osteogenesis imperfecta.

BACKGROUND: Osteogenesis imperfecta (OI) is a rare condition in which bones are abnormally brittle with frequent fractures. A variety of therapeutic agents has been used with low efficacy. In this study, we present three patients treated for 4 years with i.v. pamidronate. PATIENTS AND METHODS: Three prepubertal patients, aged 9 (M), 9 (F) and 11 (F) years old, with OI, were treated with 30-60 mg i.v. pamidronate every 6 months over four years. Determinations were made of plasma 1,25-dihydroxycholecalciferol, 25-hydroxycholecalciferol, insulin-like growth factor-I (IGF-I) and its transport protein (IGFBP3), osteocalcin, total alkaline phosphatase and its osseous fraction, and parathormone (PTH) at baseline and after every pamidronate infusion, Densitometry and X-ray of the vertebral column were performed at the same intervals. RESULTS: Significant reductions of number of bone fractures and pain were observed in all patients, despite lack of any modification in biochemical parameters. Lumbar X-ray and densitometry showed a striking improvement by the end of the treatment period. CONCLUSION: Pamidronate seems to be useful in the treatment of patients with osteogenesis imperfecta.

Absorptiometry, Photon↗

Deficient expression of the small proteoglycan decorin in a case of severe/lethal osteogenesis imperfecta.

In osteogenesis imperfecta (OI) the effects of mutations in type I collagen genes generally reflect their nature and localization. Unrelated individuals sharing identical mutations present, in general, similar clinical phenotypes. However, in some such cases the clinical phenotype differs. This variable clinical expression could be the result of abnormalities in other connective tissue proteins. Since decorin is a component of connective tissue, binds to type I collagen fibrils and plays a role in matrix assembly, we studied decorin production in skin fibroblasts from OI patients. Cultured fibroblasts from one patient with extremely severe osteogenesis imperfecta (classified as type II/III) who has an alpha 1(I)gly415ser mutation were found to secrete barely detectable amounts of decorin into culture medium. Western blotting using antibodies raised against decorin confirmed the reduction of the decorin core protein and Northern blot analysis showed decorin mRNA levels below the limit of detection. Cells from a patient, with a less severe phenotype, bearing a mutation in the same position of the triple helix (alpha 1(I)gly415) expressed decorin normally. The different clinical phenotypes could be due to the differing genetic backgrounds of the patients so it is tempting to conclude that in our most severely affected patient the absence of decorin aggravates the clinical phenotype.

Blotting, Northern↗

[A new mutation in COL1A1 gene in a family with osteogenesis imperfecta].

OBJECTIVE: Osteogenesis imperfecta (OI) is a congenital disease of connective tissue of increased bone fragility and low bone mass, most often caused by single amino acid substitution of glycine residues in the collagen, type I, alpha 1 protein (COL1A1) gene or the collagen, type I, alpha 2 protein (COL1A2) gene, encoding type I procollagen chains. We describe here the clinical, biochemical, and molecular characterization of a family with type I OI in China and would like to explore whether the biochemical characterization of OI in China is different from that in other countries. METHODS: Through clinical research, we study the clinical characteristic of the OI household. Genomic DNA was isolated from peripheral blood lymphocytes of the proband and his family members by saturation hydroxybenzene-chloroform methods; amplification of target COL1A1 gene by Polymerase chain reaction with 23 pairs of different primers; purification; direct sequencing of the Polymerase chain reaction product. According to the mutation site, we took restriction enzyme analysis to 50 normal control people. RESULTS: We found a G and A heterozygosis mutation at the exon 48 causing an a1 (I) p. G1157D substitution in the proband and his sister who is also a sufferer of OI. At the same time, other normal people in the family and other normal control people do not have this change. CONCLUSION: This is the first delineation of an aspartic acid substitution in new site of the a1 (I) chain causing nonlethal osteogenesis imperfecta. Only nine aspartic acid substitution in type I collagen has been fully reported in the world. Now we revealed a new nosogenesis of OI. Since only few of nucleotide changes in type I collagen glycine codons would result in an aspartic acid substitution, these are predicted to be infrequent. Furthermore, it is possible to suggest that nosogenesis of OI in china is different from other countries.

Base Sequence↗

A Novel Splice Variant in the COL1A1 Gene Leads to Exon 46 Skipping and Osteogenesis Imperfecta.

BACKGROUND: Osteogenesis imperfecta (OI) is a clinical and genetic disorder characterised by bone fragility, growth deficiency and skeletal deformity. Ninety per cent of OI cases are attributable to autosomal dominant variants in the COL1A1 and COL1A2 genes. METHODS: Candidate variants were identified and verified through trio whole-exome sequencing (trio-WES), copy number variation sequencing (CNV-seq) and Sanger sequencing. Minigene splicing assays were performed in HeLa and HEK293T cells with pcDNA3.1 and pcMINI-C vectors to investigate the function of the candidate variants. A systematic review of COL1A1 splicing variants and the corresponding genotype-phenotype spectrum was performed. RESULTS: Trio-WES revealed a novel heterozygous variant in the C-terminal region of the COL1A1 gene: NM_000088.4:c.3423+5G>A. Sanger sequencing confirmed the variant in both the proband (II-2) and her foetus (III-1) who were clinically suspected of having OI. The c.3423+5G>A variant causes complete skipping of Exon 46, as demonstrated by a minigene splicing assay. We retrieved 419 COL1A1 splicing variants from PubMed, excluded 15 without phenotypic data and 2 linked to Ehlers-Danlos syndrome and stratified the remaining 402 variants into three types on the basis of splice site location: (1) Variants at canonical splicing sites (77.8%, 313/402) mostly cause mild phenotypes, whereas a minority may be severe. (2) Intron variants in other locations, such as splice region variants (17.9%, 72/402), usually cause mild clinical phenotypes, and deep intronic splice variants (0.4%, 2/402) that may result in severe phenotypes. (3) Other variants (3.7%, 15/402), such as exon variants or fragment loss, are extremely rare. We also preliminarily discuss the mechanisms underlying phenotypic variability and the characteristics of C-terminal variants. CONCLUSIONS: This intron variant in COL1A1 was classified as likely pathogenic and was confirmed to disrupt COL1A1 expression. The summary analysis results also revealed a correlation among splicing variants, C-terminal region variants and disease, suggesting that variant location provides a useful framework for prognosis prediction.

Female↗

[Clinical, radiographic and laboratory evaluation of patients with osteogenesis imperfecta].

BACKGROUND: Osteogenesis imperfecta is a genetic disorder characterized by defects in type I collagen. The main symptom is bone fragility and susceptibility to fractures. Other clinical findings are dentinogenesis imperfecta, blue sclera, early deafness and joint laxity. The purpose of this paper is to establish a practical relationship of the clinical differences between the Sillence's groups. METHODS: 22 patients were classified according to Sillence et al criteria and submitted to laboratory tests including blood calcium level and bone densitometry. RESULTS: All clinical and laboratory differences were discussed in the text. CONCLUSIONS: Differences such as results that were found in walking ability, height and bone densitometry were significant and may help to classify patients and to establish prognosis.

Absorptiometry, Photon↗