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Splice site mutation causing deletion of exon 21 sequences from the pro alpha 2(I) chain of type I collagen in a patient with severe dentinogenesis imperfecta but very mild osteogenesis imperfecta.

An eight-year-old boy was referred for dental assessment of dentinogenesis imperfecta, a full clinical examination also revealed joint hypermobility and some features of mild osteogenesis imperfecta although he had suffered few fractures. Analysis of the collagens produced by both gingival and skin fibroblast cultures showed the synthesis and intracellular retention of an abnormal alpha 2(I) chain that migrated faster than normal on SDS-PAGE. Cyanogen bromide peptide mapping of this intracellular protein indicated a probable deletion in the N-terminal peptide alpha 2CB4. The denaturation temperature of the mutant protein was only 36 degrees C, some 6 degrees C below normal. At 37 degrees C secretion of abnormal protein was not detectable but a lower temperature (30 degrees C) some was secreted into the medium. RT-PCR amplification of mRNA coding for alpha 2CB4 revealed a heterozygous deletion of the 108 bp exon 21 of COL1A2. Sequencing of PCR amplified genomic DNA identified a G --> A transition in the moderately conserved + 5 position of the IVS 21 5' consensus splice site causing the skipping of exon 21. Hybridization with allele-specific oligonucleotides showed no other family member had this base change. Since the cDNA deletion was associated with the (-) allele of a Pvu II polymorphism in exon 25 of COL1A2 we could demonstrate that the mutant pre-mRNA was alternatively spliced yielding both full length and deleted transcripts. Family genotype analysis indicated the mutation had originated in the paternal alpha 2(I) gene.

Alternative Splicing↗

[The radiology of osteogenesis imperfecta].

The term "osteogenesis imperfecta" refers to a heterogeneous group of hereditary diseases characterized by osteopenia, increased bone fragility, blue sclerae and dentinogenesis imperfecta. The abnormal synthesis of type-I collagen is responsible for the pathologic changes occurring not only in bone, but also in skin, tendons and ligaments, sclerae and teeth. The clinical and radiographic features of 5 cases (2 males and 3 females; age range: 1 month to 29 years) were analyzed. The patients were unrelated with each other. The diagnosis of the different types of osteogenesis imperfecta is as difficult as the identification of the various genotypes which are responsible for the different clinical pictures. The most characteristic radiographic pattern--which is observed in any type of the disease--consists in osteopenia associated, in most cases, with multiple fractures and deformities--e.g., micromelia, large metaphysis, archon long bones. Typically, "pop corn" calcifications are observed in both epiphysis and metaphysis of long bones. Dentinogenesis imperfecta is one of the most significant clinical patterns, and it can be the only bone abnormality. The prognosis of osteogenesis imperfecta is as varied as its genetics--i.e., the fractures discovered at birth are not necessarily a negative prognostic sign.

Adolescent↗

Cyclic administration of pamidronate in children with severe osteogenesis imperfecta.

BACKGROUND: Severe osteogenesis imperfecta is a disorder characterized by osteopenia, frequent fractures, progressive deformity, loss of mobility, and chronic bone pain. There is no effective therapy for the disorder. We assessed the effects of treatment with a bisphosphonate on bone resorption. METHODS: In an uncontrolled observational study involving 30 children who were 3 to 16 years old and had severe osteogenesis imperfecta, we administered pamidronate intravenously (mean [+/-SD] dose, 6.8+/-1.1 mg per kilogram of body weight per year) at 4-to-6-month intervals for 1.3 to 5.0 years. Clinical status, biochemical characteristics reflecting bone turnover, the bone mineral density of the lumbar spine, and radiologic changes were assessed regularly during treatment. RESULTS: Administration of pamidronate resulted in sustained reductions in serum alkaline phosphatase concentrations and in the urinary excretion of calcium and type I collagen N-telopeptide. There was a mean annualized increase of 41.9+/-29.0 percent in bone mineral density, and the deviation of bone mineral density from normal, as indicated by the z score, improved from -5.3+/-1.2 to -3.4+/-1.5. The cortical width of the metacarpals increased by 27+/-20.2 percent per year. The increases in the size of the vertebral bodies suggested that new bone had formed. The mean incidence of radiologically confirmed fractures decreased by 1.7 per year (P<0.001). Treatment with pamidronate did not alter the rate of fracture healing, the growth rate, or the appearance of the growth plates. Mobility and ambulation improved in 16 children and remained unchanged in the other 14. All the children reported substantial relief of chronic pain and fatigue. CONCLUSIONS: In children with severe osteogenesis imperfecta, cyclic administration of intravenous pamidronate improved clinical outcomes, reduced bone resorption, and increased bone density.

Adolescent↗

Mild forms of dentinogenesis imperfecta in association with osteogenesis imperfecta as characterized by light and transmission electron microscopy.

Osteogenesis imperfecta (OI) results from various gene mutations leading to defects in type I collagen, which is the major component of both bone and dentin. Yet dentinogenesis imperfecta (DI) is found only in half of the patients with OI. Here we document patients from three families with OI and DI lacking the clinical and radiographic features of DI in permanent teeth. However, light and transmission electron microscopic studies of dentin of deciduous and permanent teeth revealed various changes in the morphology of the dentinal tubules and collagen fibers. In one family, diagnosis of DI preceded that of OI. The grade of severity of dentinal manifestations in patients with OI apparently forms a continuum from normal dentin structure to severe DI, and the marked difficulty in diagnosing mild DI may have led to underestimating its frequency. Furthermore, patients with DI should be carefully examined for the possible presence of OI.

Child↗

Management of pregnancy in osteogenesis imperfecta: new perspectives.

Osteogenesis imperfecta during pregnancy presents increased risk to mother and fetus. In addition to the well-known skeletal changes, other recently recognized metabolic abnormalities also may lead to maternal and fetal problems during labor and delivery. A discussion of risk factors and their managment is presented. The importance of considering the possibility of fetal osteogenesis imperfecta is stressed, and cesarean section is presented as the method of choice for delivery. Important genetic factors including the lack of correlation between the severity of involvement of parent and offspring and the use of pyrophosphate analyses are discussed. An illustrative case is presented.

Adult↗

Osteogenesis imperfecta type II: prenatal sonographic diagnosis.

Sonograms of fetuses at risk for congenital lethal osteogenesis imperfecta (osteogenesis imperfecta type II) were retrospectively reviewed blindly and correlated with pregnancy outcomes. Six of eight cases of type II osteogenesis imperfecta were correctly diagnosed with use of the proposed criteria of multiple fractures, demineralization of the calvaria, and femoral length more than 3 standard deviations below the mean for gestational age. The two cases not diagnosed had sonographic abnormalities but did not meet all three criteria. Among 18 pregnancies genetically at risk for the disease but with normal outcomes, all sonograms were normal, meeting none of the proposed criteria. Among an additional 25 fetuses with osteochondrodysplasias, no case satisfied all three of the proposed diagnostic criteria. With use of strict standards for the diagnosis of type II osteogenesis imperfecta, this disease can be distinguished from other fetal skeletal abnormalities. In a pregnancy at risk for recurrence of osteogenesis imperfecta, a normal sonogram after 17 weeks excludes this lethal condition.

Female↗

[Hearing loss in osteogenesis imperfecta--casuistic demonstration].

INTRODUCTION: Osteogenesis imperfecta (OI) is a genetic disorders of connective tissue. Hearing loss has been repeatedly reported as a major syndrome of osteogenesis imperfecta. The hearing loss in OI is predominantly of the conductive type. MATERIAL AND METHODS: The family (mother and two daughters) suffering from osteogenesis imperfecta are presented. RESULTS: Audiological examination is presented. It revealed various types of hearing loss in members of family (conductive, sensorineural, mixed). CONCLUSIONS: On this example variety of hearing problems in this disease are demonstrated. Etiology and classification of osteogenesis imperfecta, clinical proceeding and treatment are presented.

Adolescent↗

Hypercalciuria in osteogenesis imperfecta type I.

BACKGROUND: In Osteogenesis Imperfecta severity of disease and reduced physical activity have been considered the main factors contributing to hypercalciuria; however, its pathogenesis in Osteogenesis Imperfecta Type I, in which mobility is normal, is still unclear. PATIENT, METHODS AND RESULTS: We describe a patient with Osteogenesis Imperfecta Type I and hypercalciuria, in whom measurement of calcium intake, plasma 1 - 25(OH) (2) Vitamin D, fasting calciuria and tubular proteinuria led us to exclude an absorptive or renal component in the pathogenesis of hypercalciuria. CONCLUSIONS: We believe that hypercalciuria is determined by bone disease in Osteogenesis Imperfecta Type I. This condition should be added to the causes of normocalcemic hypercalciuria in children and the mildest forms should be differentiated from Idiopathic Hypercalciuria.

Age Factors↗

[Influence of bisphosphonate treatment on the radiological features of osteogenesis imperfecta in children].

The Osteogenesis imperfecta (OI) is a hereditary disturbance of collagen biosynthesis. The illness is characterized by frequent fractures that consequently cause functional disturbance of locomotion system as well as deformation of long tubular bones. The purpose of the present work was to study radiological features of clinical forms of osteogenesis imperfecta during bisphosphonate treatment in children according to the schemes we developed taking into consideration the type of illness and the age of the patient. The total number of 32 patients, aged 1-15, suffering from osteogenesis imperfecta, have been investigated. The patients have been divided into three groups depending on the type of illness (I, III and IV type). Type II (lethal form) has not been observed by us. All patients, participating in the study underwent radiological examination of tubular bones and vertebra pre and post treatment. The results of the study showed that bisphosphonate treatment has positive effects in patients of type I and IV of osteogenesis imperfecta and is less effective in the type III of the diseases.

Adolescent↗

Aspects of the history of osteogenesis imperfecta (Vrolik's syndrome).

Osteogenesis imperfecta (OI) or Vrolik's syndrome is a heterogeneous group of inherited conditions arising from a variety of biochemical and morphological collagen defects. It was Willem Vrolik, Professor of Anatomy, Pathological Anatomy and Zoology at the Athenaeum Illustre (University of Amsterdam), who described in his Handbook of Pathological Anatomy (1842-1844) and Tabulae ad illustrandam embryogenesin hominis et mammalium, naturalem tam abnormem (1844-1849) a newborn infant with numerous fractures and hydrocephalus. In the Tabulae, having both Latin and Dutch texts, in the Latin text Vrolik used in the heading of Plate 91 the term Osteogenesis imperfecta (in Dutch: gebrekkige beenwording). Vrolik also mentioned that the infant lived three days and that both the parents were suffering from lues universalis at the time of birth. On our reexamination, the whole skeleton appeared poorly mineralised. The fairly large skull exhibited a broad and high forehead, large fontanels, frontal and temporal bossing, shallow orbits, and a protruding occiput. The calvaria consisted of many Wormian bones. The tubular bones, although of normal length and only slightly curved, were very thin, as were the ribs. All the skeletal structures showed one or more fractures and many fractures showed callus formation. In 1998 we re-diagnosed the condition of the specimen as osteogenesis imperfecta type II. Willem Vrolik was one of the first to realize that many skeletal dysplasias were not the result of a postnatal acquired disease, such as "rickets" or "osteomalacia" as many of his contemporaries believed. He thought that it might be due to insufficient intrinsic "generative energy." He substantiated this by stating that in this specimen a primary impairment of ossification is present and not a secondary degeneration. The descriptions given by Willem Vrolik in some of the specimens generated the term Osteogenesis imperfecta and the eponym Vrolik's syndrome for this genetic disorder characterized by increased fragility.

Bone and Bones↗

Functional significance of bone density measurements in children with osteogenesis imperfecta.

BACKGROUND: The treatment of osteogenesis imperfecta has been directed at improvement of bone mineral density, yet the importance of bone mineral density in predicting functional and clinical outcome in this patient population has not been demonstrated. We used a validated functional outcome measure to identify the relationship between bone mineral density and physical function in children with osteogenesis imperfecta, and we also evaluated the relationship of bone mineral density to the rate of surgery and fracture in patients with osteogenesis imperfecta. METHODS: Twenty patients (age range, four to seventeen years) with osteogenesis imperfecta who had undergone bone mineral densitometry as measured by dual x-ray absorptiometry of the lumbar spine, wrist, and proximal aspect of the femur between November 1999 and April 2001 were retrospectively analyzed. Functional outcome was measured with use of the Pediatric Outcomes Data Collection Instrument. These questionnaires were completed by the parents of all twenty patients and, in addition, by fifteen patients in the study who were between the ages of eleven and eighteen years. Fracture and surgery rates were calculated on the basis of the number of documented fractures and surgical procedures that the patient had had from the time of the initial presentation until the time of the latest follow-up visit. RESULTS: There were significant relationships between the bone mineral density of the lumbar spine and the scores obtained on the parent-completed questionnaires with regard to upper-extremity functioning (r = 0.57, p < 0.01), transfers and basic mobility (r = 0.55, p = 0.01), sports and physical functioning (r = 0.55, p = 0.01), and global functioning (r = 0.60, p < 0.004). There were also significant relationships between the bone mineral density of the wrist and the scores obtained on the child-completed questionnaires with regard to upper-extremity functioning (r = 0.82, p < 0.01), sports and physical functioning (r = 0.76, p < 0.01), and global functioning (r = 0.83, p = 0.001). There were significant negative relationships between the bone mineral density of the lumbar spine and the rate of fractures (r = -0.69, p < 0.001) and the bone mineral density of the lumbar spine and the rate of surgery (r = -0.60, p < 0.01). CONCLUSIONS: There is a relationship between bone mineral density and the functional outcome, rate of fracture, and rate of surgery in patients with osteogenesis imperfecta. Bone mineral density appears to be an indicator of disease severity and may be predictive of long-term functional outcome. To establish specific guidelines for treatment, more data on normative bone-mineral density in children with osteogenesis imperfecta will be needed.

Adolescent↗

Osteogenesis imperfecta with bleeding diathesis.

Osteogenesis imperfecta (OI) is a disorder of type 1 collagen synthesis with varied complications in form of brittle bones, hearing loss, dental, skin, and ocular changes. Osteogenesis imperfecta may have bleeding diathesis rarely due to defective vascular integrity for the same reason. Here we come across a rare case of Sillence type IB Osteogenesis imperfecta with bleeding in the form of repeated epistaxis and petechial rash, which seem to have a collagenous link.

Child↗

Effect of long-term calcitonin therapy on the clinical course of osteogenesis imperfecta.

10 children with osteogenesis imperfecta, 4 with "tarda" and 6 with "congenita" varieties of the disease, were treated with salmon calcitonin (SCT) for intervals ranging from 14 to 35 months. Responses to SCT therapy in patients with osteogenesis imperfecta tarda were characterized by an apparent decreased fracture incidence in three, a fall in either alkaline or acid phosphatase, and a rate of increase in forearm bone mass which was greater than that observed in an untreated "tarda" population. The chemical response SCT therapy varied in children with osteogenesis imperfecta congenita, only one demonstrating a decrease in both acid phosphatase and urinary hydroxyproline. Three others responded with a rise in acid phosphatase, two of whom also demonstrated a fall in urinary hydroxyproline; in two other "congenita" patients urinary hydroxyproline was actually higher after SCT treatment and acid phosphatase relatively unchanged. Alkaline phosphatase was normal in all "congenita" patients before and following the SCT treatment interval. These varied biochemical responses were associated with temporary increments in bone mass early in the treatment course, although in bone mass early in the treatment course, although one "congenita" patient with the largest calciuric response to SCT and an increase in hydroxyproline excretion demonstrated progressive increments in skeletal mineral content during a 14-month treatment interval. In both "tarda" and "congenita" subjects, parathyroid hormone was unchanged by chronic SCT treatment; SCT-antibodies were detectable although biological responsivity to SCT persisted.

Acid Phosphatase↗

Complication following intramedullary fixation with a Fixion nail in a patient with osteogenesis imperfecta: a case report.

Osteogenesis imperfecta (O.I.) is a genetic disorder with increased bone fragility and low bone mass. We report the history of a 17-year-old male patient with O.I. who presented a fracture of his left femoral shaft. He had osteogenesis imperfecta type I A according to Silence. He had presented two years previously an ipsilateral cervical fracture of the femur which had healed. Intramedullary fixation with a Fixion intramedullary nail was elected. While the Fixion nail was being inflated to 70 bars with saline, a longitudinal fracture occurred in the femoral shaft. A conventional intramedullary nail and cerclage wire were applied for fixation. The fracture healed without complication in 10 weeks. Based on this observation, we do not recommend using the Fixion IM nail for fracture fixation in patients who have abnormal bone fragility such as in osteogenesis imperfecta.

Adolescent↗

A case of chondrodysplasia punctata with features of osteogenesis imperfecta type II.

The osteogenesis imperfecta syndromes constitute a group of heterogeneous, heritable skeletal dysplasias. Of the 4 types, type II is the most severe, with an incidence of 1 per 55,000. It is characterized by malformed bones secondary to abnormal collagen type I synthesis. Affected fetuses are divided into 3 groups: A, B, and C. All groups have long bones described as "wrinkled" or "crumpled" secondary to repeated fractures. Many bones also show evidence of demineralization, which is especially evident in the bones of the face and calvaria. In groups A and C, the chest is generally small, with thickened and shortened ribs, and each rib has characteristic "beading" patterns secondary to repeated fracturing. Sonography has traditionally been successful in the diagnosis of osteogenesis imperfecta at an early gestational age. Chondrodysplasia punctata describes a heterogeneous group of skeletal disorders characterized by abnormal mineralization of bones during gestation. There are many different causes of it, but some of the specific subtypes include rhizomelic, X-linked dominant (also known as Conradi-Hünermann syndrome), X-linked recessive, and tibia-metacarpal. We report a case of severe X-linked dominant chondrodysplasia punctata, which sonographically had common features with osteogenesis imperfecta type II.

Adult↗

Osteogenesis imperfecta--clinical and molecular diversity.

Osteogenesis imperfecta is a heritable disorder of bone formation resulting in low bone mass and a propensity to fracture. It exhibits a broad range of clinical severity, ranging from multiple fracturing in utero and perinatal death to normal adult stature and a low fracture incidence. The disorder is currently classified into seven types based on differences in clinical presentation and bone architecture. Mutation in one of the type I collagen genes is commonly associated with osteogenesis imperfecta, but is not a prerequisite for the diagnosis. Indeed, the newer forms of osteogenesis imperfecta (types V, VI and VII) are not associated with type I collagen gene defects. Amongst the type I collagen gene mutations that can occur, missense base substitutions involving glycine codons in the exons encoding the central triple-helix forming domain predominate. Such mutations can occur in all the classical forms of osteogenesis imperfecta (types I-IV), but genotype/phenotype correlations are complex and often unpredictable. Treatment of osteogenesis imperfecta by bisphosphonate therapy can improve bone mass in all types of the disorder, and while not being a cure for the disorder does improve the quality of life of the patient.

Genetic Variation↗

Phenotypic variability and abnormal type I collagen unstable at body temperature in a family with mild dominant osteogenesis imperfecta.

Autosomal dominant inheritance of a mild form of osteogenesis imperfecta (osteogenesis imperfecta type I) with different phenotypic expression was found in a family. Phenotypic expression was different for the affected mother and son, in the presence of the same biochemical results. Dermal fibroblast cultures synthesized normal and mutant type I collagen alpha chains. Collagen heterotrimers containing abnormal chains were overmodified along the entire triple helical domain and showed an unusually low denaturation temperature, so far found only in lethal cases. The mild phenotype in the family is probably due to the fact that abnormal type I collagen molecules are more likely to be degraded than utilized in the extracellular matrix.

Body Temperature↗

Prenatal ultrasonographic diagnosis of osteogenesis imperfecta.

Between 1982 and 1986, osteogenesis imperfecta was diagnosed by ultrasound in seven fetuses. The known heterogeneity of osteogenesis imperfecta was confirmed by the prenatal ultrasonographic findings. Dependent on the type of osteogenesis imperfecta, the appearance of the limbs varied from severely shortened and broad, with very low echogeneity and absent acoustic shadow (type IIA), to only moderately shortened and thin, with almost normal echogeneity and acoustic shadow but clearly visible fractures causing angulation of the bone (types IIC and III). Ultrasonography offers the possibility to detect or exclude the lethal and severe forms of osteogenesis imperfecta early (type IIA) or halfway (types IIB, IIC, and III) through the second trimester. Prenatal diagnosis of the disease allows the option of elective abortion or may prevent unnecessary obstetric intervention.

Adult↗