Osteogenesis imperfecta and malignant hyperthermia. Is there a relationship?

We describe a patient with osteogenesis imperfecta who developed tachycardia, metabolic and respiratory acidosis (pH 7.14, PCO2 8.4 kPa, BE -8.5 mmol.l-1) and hyperthermia up to 40 degrees C during anaesthesia with barbiturates, fentanyl, pancuronium, and nitrous oxide. Malignant hyperthermia was suspected and the patient treated accordingly. Two years later the in-vitro contracture test for malignant hyperthermia was completely normal. We conclude that hypermetabolism in patients with osteogenesis imperfecta is due to unknown mechanisms other than malignant hyperthermia.

[Bone mineral content in osteogenesis imperfecta]

Bone mineral content (BMC) in the radius of 23 osteogenesis imperfecta (OI) patients (1-26 yr) was measured with SPA technique. Comparing the values of OI type I. patients with that of type III. patients, the decrease of BMC was more prominent in the latter group, however, the two group hadn't been distinct from each other at p < 0.05 level. Based on the measurements of 39 relatives (mother, father, brother) the method seems not to be helpful in screening of gene-carrying relatives because of the high variability of the phenotype of the disease. Follow-up SPA studies-avoiding the repositioning errors-inform about the therapeutic effect.

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.

The prognosis for walking in osteogenesis imperfecta

We report a postal survey of 59 families of children with osteogenesis imperfecta. From the 51 replies we collected data on developmental milestones and walking ability and related them to the Sillence and the Shapiro classifications of osteogenesis imperfecta. Twenty-four of the patients had been treated by intramedullary rodding. Both classifications helped to predict eventual walking ability. We found that independent sitting by the age of ten months was a predictor for the use of walking as the main means of mobility with 76% attaining this. Of the patients who did not achieve sitting by ten months, walking became the main means of mobility in only 18%. The developmental pattern of mobility was similar in the rodded and non-rodded patients.

Arachnoid cyst and chronic subdural haematoma in a child with osteogenesis imperfecta type III resulting from the substitution of glycine 1006 by alanine in the pro alpha 2(I) chain of type I procollagen

The features of a child with osteogenesis imperfecta type III (OI III) resulting from the heterozygous substitution of glycine 1006 by alanine in the pro alpha 2(I) chain of type I procollagen were studied. He was born at term with the clinical features of severe OI, including deep grey-blue sclerae. He had severe osteopenia and all long bones were smaller than normal with cortical thinning, metaphyseal expansion, poor metaphyseal modelling, and multiple fractures. However, the vertebrae, pelvis, and shoulder girdle were of normal shape and there were few rib fractures. Histological examination of the calvarium and tibial shaft showed woven bone without lamellar bone or Haversian systems. The shafts of the long bones were widened owing to repeated fractures. Progressive enlargement of the calvarium occurred between 3 and 4.5 months of age owing to bilateral chronic subdural haematomata and a large arachnoid cyst in the Sylvian fissure. The cyst was probably developmental in origin while the subdural collections were probably the result of perinatal skull trauma. The cyst and the subdural collections resolved following drainage but ventricular dilatation with normal cerebrospinal fluid pressure followed. The proband is the first reported case of OI with a glycine substitution by alanine in the pro alpha 2(I) chain of type I procollagen.

A Gly238Ser substitution in the alpha 2 chain of type I collagen results in osteogenesis imperfecta type III

In general, osteogenesis imperfecta (brittle bone disease) is caused by heterozygous mutations in the genes encoding the alpha 1 or alpha 2 chains of type I collagen (COL1A1 and COL1A2, respectively). In this study we screened these genes in a proband presenting with the severe form (type III) of osteogenesis imperfecta for mutations which might result in the phenotype. Single-strand conformation polymorphism mapping analysis was used to identify a region suspected of harbouring the mutation and subsequent sequence analysis revealed a heterozygous G to A transition in the alpha 2(I) gene of type I collagen in the individual. The resulting substitution of the glycine at position 238 of the alpha chain by serine is the most N-terminal yet reported for this chain.

[Prenatal diagnosis of osteogenesis imperfecta. Report of a case classified as the classical Vrolik lethal type]

Report on prenatal sonographic diagnosis of osteogenesis imperfecta of the classical type "letalis Vrolik" in the case of a fetus in the 20th/21st week of pregnancy. The prenatal diagnosis of this kind of osteogenesis imperfecta is based on the soft membranous cranium (Caput membranacium), the microthorax caused by the bell-shaped configuration of the ribs and the diaphysis of the long bones which are too short for the age of pregnancy. These symptoms are first of all the consequence of a disturbed bone formation and mineralisation; its basis is a connatal deficit of collagen synthesis. The sonographic differential diagnosis to the type "Ekman Lobstein" of osteogenesis imperfecta and thanatophoric dwarfism are discussed.

Substitution of serine for glycine 883 in the triple helix of the pro alpha 1 (I) chain of type I procollagen produces osteogenesis imperfecta type IV and introduces a structural change in the triple helix that does not alter cleavage of the molecule by procollagen N-proteinase

Type I procollagen secreted by dermal fibroblasts from an individual with osteogenesis imperfecta type IV was a mixture of normal molecules and molecules that were post-translationally overmodified. The individual was heterozygous for a G to A transition in the COL1A1 gene that resulted in the substitution of serine for glycine 883 in one or both of the pro alpha 1 (I) chains. The thermal stability of molecules containing overmodified chains was lower by 2 degrees C than that of normal molecules. However, following cleavage of the molecules with vertebrate collagenase, the temperature of denaturation of the overmodified A fragments (residues 1-775 of the helix did not contain the substitution) was 2 degrees C greater than that of A fragments from normal molecules. The rates of cleavage by procollogen N-proteinase (EC 3.4.214.14) (N-proteinase) of procollagen molecules in normal and osteogenesis imperfecta samples were not significantly different. The procollagen molecules in the osteogenesis imperfecta sample were also indistinguishable from those in control samples by rotary shadowing electron microscopy. The results suggest that this substitution of serine for glycine in the alpha 1 (I) chain of procollagen, like the substitution of aspartate for the same glycine previously described (Lightfoot, S. J., Holmes, D. F., Brass, A., Grant, M. E., Byers, P. H., and Kadler, K. E. (1992) J. Biol. Chem. 267, 25521-25528), can alter the structure of the triple helix N-terminal to the site of the substitution. However, in contrast to the aspartate for glycine substitution, the structural change is insufficient to delay the cleavage of the procollagen by N-proteinase and results in a mild rather than lethal phenotype.

[Prenatal diagnosis of osteogenesis imperfecta]

The authors report a prenatal diagnosis of osteogenesis imperfecta or Porak and Durante disease, in which the child survived. The diagnosis was made by ultrasonography which revealed major abnormalities of osteogenesis more particularly affecting the lower limbs, which were short and deformed. Other essential features of this syndrome are osteoporosis, hyperrelaxation of ligaments and blue sclerae. This rare and genetic condition is due to type I collagen abnormalities. It is often governed by dominant transmission but manifestation of the gene is variable within a given family. Molecular biology and genetic studies offer new possibilities of prenatal diagnosis, but ultrasonography remains the investigation of choice, possibly helped by X-ray of the uterine contents.

Bone density in osteogenesis imperfecta may well be normal

Osteogenesis imperfecta (OI) is often regarded as a form of osteoporosis. However, the bone fragility is the result of defective collagen and earlier work has demonstrated that cortical thickness, in bones not previously fractured, is usually normal. We have now measured the bone mineral content of the distal forearm in 61 adult patients with well characterized OI. Three patients with the Silence type III disorder had bone mass values well below the reference interval. For the 47 type I patients and 11 type IV patients, the bone mass was significantly lower than normal (P < 0.001). However 70% of patients had values within the reference interval. One cannot therefore exclude the diagnosis of OI by finding normal values with densitometry. Diagnostic difficulties do not occur in type III patients and our main objective was to recruit as many individuals as possible with OI types I and IV. In the type IV disease, the diagnosis can be particularly difficult without a positive family history. Since the evaluation of bone density by subjective examination of radiographs is a much less precise procedure, most patients with type I and IV OI would be expected to have 'normal' appearances with this assessment. Osteogenesis imperfecta cannot be excluded on the basis of apparently normal bone density or cortical thickness with routine radiographs.

[Prenatal diagnosis of osteogenesis imperfecta. Report of a case classified as the classical Ekman Lobstein type]

Report on prenatal sonographic diagnosis of osteogenesis imperfecta of the classical type Ekman Lobstein (osteopsathyrosis) in the 35th week of pregnancy. We could demonstrate the marked penetration of ultrasound through the characteristically very thin long bones even before the occurrence of fractures. Difficulties in attributing our case to one of the four groups of osteogenesis imperfecta according to Sillence are discussed, as well as the obstetrical management of these prenatally diagnosed cases.

Craniocervical abnormalities in osteogenesis imperfecta: genetic and molecular correlation

Basilar impression (BI) assessed by either plain lateral skull radiograph or computerized tomography (CT) sagittal reconstruction of the craniocervical junction is a common finding occurring in 25% of subjects with osteogenesis imperfecta (OI). It appears to occur with highest frequency in a group of subjects with OI type IV B, i.e. patients with mild/moderate liability to fractures, normal sclerae but dentinogenesis imperfecta. Neurologic signs indicating compression of posterior fossa structures occur predominantly in subjects with BI and OI type IV. Screening is recommended for all patients with OI but particularly OI type IV B.

[Osteogenesis imperfecta in childhood and adolescence]

BACKGROUND

209 patients with osteogenesis imperfecta type I, III and IV were studied to provide data on the natural course of the disease until the end of the second decade.

RESULTS

Weight and length at birth were normal in most cases of type I and IV, markedly reduced in type III. Fractures and deformities at birth were most frequent in type III. High fracture rates occurred in type III and IV up to 8-10 years of age. Skeletal deformities developed primarily in the lower extremities and the spine, again most frequently in type III. Radiological features were--besides osteopenia--Wormian bones of the skull, pseudoarthroses, deformity of the pelvis, popcorn epiphyses (most frequent in type III) and hyperplastic callus (most frequent in type IV). Longitudinal growth of patients with type I was in the lower normal range, while patients with type III and IV developed marked growth deficiency. Motor performance was not severely impaired in most cases of type I; however, all type III patients and 71% of type IV patients were confined to a wheelchair in later life.

CONCLUSION

As defined, type I patients had a mild clinical course until early adulthood. Type III and IV represented a spectrum of severely affected patients. Although type IV patients were less affected at birth, their postnatal course in some respects resembled that of type III.

[Lethal osteogenesis imperfecta in a Congolese newborn infant]

BACKGROUND

Several forms of osteogenesis imperfecta have been described. The perinatally lethal forms (type II of Sillence) have been subclassified into groups A, B and C on the basis of radiological features. This report describes a case of type IIA.

CASE REPORT

A female Congolese baby was born at term to healthy, non-consanguineous parents. No ultrasonographic studies were done during the pregnancy. The newborn suffered from acute respiratory distress at birth. Clinical examination showed bone abnormalities: shortened and bowed limbs with crepitation at mobilization, soft calvaria and narrow rib cage. X-rays showed short, broad, bowed long bones with signs of fractures; the ribs were thin and beaded; wormian bones were seen in the skull. The newborn died from respiratory distress at the age of 5 hours. All clinical and X-rays investigations of the parents, the elder brother and cousins were normal.

CONCLUSION

This baby seems to have suffered from a lethal form of osteogenesis imperfecta, probably type IIA of Sillence.

Hip and knee replacement in osteogenesis imperfecta

Five total hip and three total knee arthroplasties were performed, from 1969 to 1990, in six patients who had osteogenesis imperfecta. The patients who had a hip arthroplasty were followed for a mean of seven years, and those who had a knee arthroplasty, for a mean of ten years. Postoperatively, all had relief of pain and were able to walk; one patient used a walker and two used a cane. The only postoperative complication was an intrapelvic protrusion of the acetabular component six years after a bipolar hip replacement.

[Osteogenesis imperfecta. Reflections after the prenatal diagnosis of 2 cases]

The authors report two cases of prenatal diagnosis of osteogenesis imperfecta (OI) of type II according to the classification of Sillence. When dwarfism had been discovered with deformities, fractures and low bone density, the diagnosis was made in one case at 24 and the second at 20 weeks of amenorrhoea. A recent review of the literature shows that the ideas concerning OI have changed markedly recently. All agree that within the framework of classification of diseases that there is a single entity. A dominant autosome genetic transmission is increasingly considered to be the cause for all forms of the condition. The physiopathology of collagen makes it easier to understand why these should be clinical forms. The ability to localise deleterious genes by using molecular biology makes it likely a very early antenatal diagnosis will be possible. All the same, this optimism has to be tempered with the frequent discovery in this illness of mosaicism which still leaves a large place for ultrasound.

[Osteogenesis imperfecta: report of two cases]

Osteogenesis imperfecta (OI) is a heterogenous group of inherited conditions arising from a variety of biochemical and morphological collagen defects. We report 2 cases with a clinical diagnosis of OI. The first case was classified as Silence type IIA. He was delivered at 38 weeks' gestation with severe bowing of long bones, blue sclera and craniotabes at birth. Radiographs showed severe generalized osteoporosis, broad and crumpled long bones, beading ribs and poorly mineralized skull. Histological examination of the long bones revealed the trabecula of the calcified cartilage with an abnormally thin layer of osteoid & the bony trabeculae were thin and basophilic. The second case was classified as Sillence type III. She was delivered at 39 weeks' gestation. Short, bowed lower extremities but normal color of sclerae were noted after birth. Radiographs revealed L't femoral fracture and callus formation of R't 8th rib. She survives till now with gradual deformity of long bone and growth retardation. Because of the poor prognosis of Sillence type II and type III, there is no doubt that accurate genetic counseling and prenatal diagnosis will become important in the management of the disease.

[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.

New autosomal recessive syndrome of sparse hair, osteopenia, and mental retardation in Mennonite sisters

We report on 2 Mennonite sisters with a syndrome of sparse hair, osteopenia, mental retardation, minor facial abnormalities, joint laxity, and hypotonia. Their asymptomatic consanguineous parents (inbreeding coefficient F = 1/64) have 6 other offspring, 3 of whom died in infancy of type II osteogenesis imperfecta (OI), and 3 of whom are normal. We analyzed collagens synthesized by cultured fibroblasts from these 2 sisters and their parents and detected no major abnormalities. Results of chromosomal and metabolic evaluations including amino acid analysis of plasma, urine, and hair were unremarkable. A literature search and survey of a computerized syndrome identification database did not disclose an identical phenotype. The sisters bear superficial resemblance to several known syndromes which we excluded on clinical and/or biochemical grounds. We conclude that they represent a new autosomal recessive syndrome, distinct from type II OI and perhaps unique to the Mennonite population or to this particular family.