Dental and craniofacial characteristics caused by the p.Ser40Leu mutation in IFITM5

Severe forms of osteogenesis imperfecta (OI) are usually caused by mutations in genes that code for collagen Type I and frequently are associated with craniofacial abnormalities. However, the dental and craniofacial characteristics of OI caused by the p.Ser40Leu mutation in the IFITM5 gene have not been reported. We investigated a 15‐year‐old girl with severe OI caused by this mutation. She had marked deformations of extremity long bones. There were no clinical or radiological signs of dentinogenesis imperfecta, but one tooth was missing and several teeth were impacted. Cone beam computed tomography revealed a generalized osteopenic appearance of the craniofacial skeleton, bilateral enlargement of mandibular bodies, and areas of cortical erosions. The cranial base and skull showed a generalized granular bone pattern with a mixture of osteosclerosis and osteolysis. Sphenoid and frontal sinuses were congenitally missing. Cephalometric analysis indicated a Class III growth pattern. In this case, the IFITM5 p.Ser40Leu mutation did not affect tooth structure but was associated with deformities in craniofacial bones that resemble those in the other parts of the skeleton.     

A family with homozygous and heterozygous p.Gly337Ser mutations in COL1A2

Osteogenesis imperfecta (OI) is commonly caused by monoallelic mutations in COL1A1 or COL1A2. Biallelic mutations are extremely rare. Only five previous reports have identified seven OI patients with homozygous mutations in COL1A2. OI is a genetically and phenotypically heterogeneous disorder which challenges an establishment of genotype-phenotype correlation. Notably, more than thirty patients with OI possess the heterozygous mutation, p.Gly337Ser, in COL1A2. Their clinical severity ranges from mild OI type I to severe types III and IV. Here, we report a 17-year-old Thai female with recurrent bone fractures, short stature, blue sclerae, triangular face, missing teeth, dentinogenesis imperfecta (DI), skeletal deformities, and scoliosis. She was diagnosed with OI type III. Her parents were second-cousin-once-removed. The father was a professional Thai boxer. Both had normal bone mineral density, no history of bone fractures, and only teeth problems. They were diagnosed with DI without OI. Whole exome sequencing identified that the proband harbored the homozygous mutation, c.1009G > A (p.Gly337Ser), in exon 19 of COL1A2 while her parents were heterozygous for this mutation. This study reports the eighth child with OI and the homozygous mutation in COL1A2; and the first two individuals with the heterozygous p.Gly337Ser mutation in COL1A2 causing an isolated DI without OI.     

Osteogenesis imperfecta with unusual skeletal lesions: report of three families

Thirteen individuals with osteogenesis imperfecta (OI) from three families were evaluated. All examined persons with OI had multilocular radiolucent, radiopaque, or radiolucent-radiopaque lesions of the maxilla and mandible. In most patients, the lesions involved the tooth bearing areas, but in two, the rami also were involved. Teeth were normal. Radiologic findings in the extragnathic skeleton included marked coarseness of trabeculae and diffuse osteopenia. It is proposed that these patients represent yet another dominantly inherited OI syndrome.     

Velocardiofacial syndrome with single central incisor

Three siblings and their mother are reported who all had cytogenetically proven velocardiofacial syndrome (VCFS). One boy had normal dental and craniofacial findings, except for an increased cranial base angle. His sister had only one central incisor in the maxilla. One central incisor had also been missing in the primary dentition. She had no labial frenulum present. Cephalometry showed a small maxillary unit length indicating mild maxillary hypoplasia, an increased anterior face height, steep mandibular plane angle, retruded chin, and a large cranial base angle. Dental measurements showed retroclined lower incisors and increased interincisal angle. A second sister had a cleft of the secondary palate. All permanent teeth were present with the exception of a missing central incisor in the lower jaw: the single lower central incisor was situated in the midline. Her cephalometry showed similar findings as in her sister. All three siblings required palate surgery for speech. Mother was not available for detailed dental and other oral investigations. A single maxillary central incisor has previously been reported in VCFS, but to our knowledge a single central incisor in the mandible has not been reported previously in this entity.     

Pubertal growth in osteogenesis imperfecta caused by pathogenic variants in COL1A1/COL1A2

PurposeShort stature is common in osteogenesis imperfecta (OI) and is usually severe in OI types III and IV. The characteristics of pubertal growth in OI have not been studied in detail.MethodsWe assessed 82 individuals with OI caused by pathogenic variants in COL1A1 or COL1A2 who had annual height data between 6 and 16 years of age at a minimum. Height velocity curves were fitted to each individual's height data to describe the pubertal growth spurt.ResultsCurve fitting was successful in 30 of the 33 individuals with OI type I (91%), in 23 of the 32 individuals with OI type IV (72%), and in 4 of the 17 participants with OI type III (24%). Pubertal growth spurt could be identified in most individuals with OI types I and IV, but rarely in OI type III. The timing of the pubertal growth spurt was similar between OI types I and IV in both sexes. However, height velocity was consistently higher in OI type I, leading to a widening height gap between OI types I and IV.ConclusionA pubertal growth spurt was present in most individuals with OI types I and IV, but rarely in OI type III.     

A cross‐sectional multicenter study of osteogenesis imperfecta in North America – results from the linked clinical research centers

Osteogenesis imperfecta (OI) is the most common skeletal dysplasia that predisposes to recurrent fractures and bone deformities. In spite of significant advances in understanding the genetic basis of OI, there have been no large‐scale natural history studies. To better understand the natural history and improve the care of patients, a network of Linked Clinical Research Centers (LCRC) was established. Subjects with OI were enrolled in a longitudinal study, and in this report, we present cross‐sectional data on the largest cohort of OI subjects (n = 544). OI type III subjects had higher prevalence of dentinogenesis imperfecta, severe scoliosis, and long bone deformities as compared to those with OI types I and IV. Whereas the mean lumbar spine area bone mineral density (LS aBMD) was low across all OI subtypes, those with more severe forms had lower bone mass. Molecular testing may help predict the subtype in type I collagen‐related OI. Analysis of such well‐collected and unbiased data in OI can not only help answering questions that are relevant to patient care but also foster hypothesis‐driven research, especially in the context of ‘phenotypic expansion’ driven by next‐generation sequencing.     

Heritable dentin defects: Nosology,pathology, and treatment

Heritable dentin defects have been divided into 2 main categories: dentinogenesis imperfecta (DI) and dentin dysplasia (DD). Recent studies have shown that they share many features in common. Of the connective tissue diseases, only osteogenesis imperfecta (OI) has been linked to these disorders. So far, no definitive relation between the type of OI and the dental involvement can be established. Familial occurrence of DI with OI cannot be comprehensively explained by mutations in type I collagen genes. No information about the gene defects in DD is available. At the ultrastructural level, the organization of the normally cross-striated collagen fibers in the dentin matrix varies markedly in patients affected by DI.     

Genotype�Cphenotype correlations in nonlethal osteogenesis imperfecta caused by mutations in the helical domain of collagen type I

Osteogenesis imperfecta (OI) is a heritable disorder with bone fragility that is often associated with short stature, tooth abnormalities (dentinogenesis imperfecta), and blue sclera. The most common mutations associated with OI result from the substitution for glycine by another amino acid in the triple helical domain of either the α1 or the α2 chain of collagen type I. In this study, we compared the results of genotype analysis and clinical examination in 161 OI patients (median age: 13 years) who had glycine mutations in the triple helical domain of α1(I) (n=67) or α2(I) (n=94). Serine substitutions were the most frequently encountered type of mutation in both chains. Compared with patients with serine substitutions in α2(I) (n=40), patients with serine substitutions in α1(I) (n=42) on average were shorter (median height z-score −6.0 vs −3.4; P=0.005), indicating that α1(I) mutations cause a more severe phenotype. Height correlated with the location of the mutation in the α2(I) chain but not in the α1(I) chain. Patients with mutations affecting the first 120 amino acids at the amino-terminal end of the collagen type I triple helix had blue sclera but did not have dentinogenesis imperfecta. Among patients from different families sharing the same mutation, about 90 and 75% were concordant for dentinogenesis imperfecta and blue sclera, respectively. These data should be useful to predict disease phenotype in newly diagnosed OI patients.     

The genetic basis of inherited anomalies of the teeth. Part 2: syndromes with significant dental involvement

Teeth are specialized structural components of the craniofacial skeleton. Developmental defects occur either alone or in combination with other birth defects. In this paper, we review the dental anomalies in several multiple congenital anomaly (MCA) syndromes, in which the dental component is pivotal in the recognition of the phenotype and/or the molecular basis of the disorder is known. We will consider successively syndromic forms of amelogenesis imperfecta or enamel defects, dentinogenesis imperfecta (i.e. osteogenesis imperfecta) and other dentine anomalies. Focusing on dental aspects, we will review a selection of MCA syndromes associated with teeth number and/or shape anomalies. A better knowledge of the dental phenotype may contribute to an earlier diagnosis of some MCA syndromes involving teeth anomalies. They may serve as a diagnostic indicator or help confirm a syndrome diagnosis.     

Osteogenesis imperfecta type I with unusual dental abnormalities

A large kindred with dominantly inherited osteogenesis imperfecta was evaluated. Affected individuals had bone fractures, blue sclerae, and hearing loss. In addition, all had dental abnormalities distinct from those previously described in other families with this syndrome. Deciduous teeth were normal in color or blue-grey. On radiographs of an early developing deciduous dentition, pulps were larger than normal. In patients with mixed dentitions, pulp chambers of deciduous teeth were partially obliterated. Increased constriction at the junctions of the crowns and roots was found in some deciduous teeth. One patient had large pulp stones in the pulp chambers of all maxillary deciduous molars. Permanent teeth were normal in color but had oval pulp chambers with apical extensions into the coronal portions of the roots, large coronal pulp stones, narrow root canals, and thin roots. Individuals in this family who did not have osteogenesis imperfecta had normal teeth. In addition, a well circumscribed radiolucency without a sclerotic periphery, involving the apices of all permanent mandibular incisors, was found in the anterior mandible in one patient. These findings support the hypothesis that this family has yet another type I osteogenesis imperfecta "syndrome".     

Odontoblast Dysfunction in Osteogenesis Imperfecta: An LM,SEM, and Ultrastructural Study

The inherited dentin defect dentinogenesis imperfecta (DI), while clinically obvious in osteogenesis imperfecta (OI) Types IB and IC, II, III, and IVB, is now thought to be present in all children with OI, in a continuum from minimal to severe dentin pathology. This collaborative study further clarifies the structural and ultrastructural dentin changes in the teeth of OI children with clinically obvious DI, and attempts to explain these in terms of odontoblast dysfunction. Collaborative studies were carried out in Melbourne, Australia, and Strasbourg, France, using light and polarized-light microscopy, scanning and transmission electron microscopy (SEM, TEM), selected-area diffraction (SAD), and x-ray spectroscopy (EDX). These showed structurally normal enamel (but containing long and broad lamellae) and a normally scalloped dentino-enamel junction (DEJ), but severe pathologic changes in the dentin. An initial narrow band of normal-appearing dentin tubules (including the mantle layer) ceased abruptly and was replaced by a wavelike laminar zone parallel to the DEJ with occluded tubules. Multiple parallel channels of 5-10 &#119 m diameter were present at right angles to the DEJ indenting this zone, some terminating in retro-curved "processes." The abnormal dentin containing these channels almost completely occluded the pulp chamber. The structural and ultrastructural changes seen can be explained on the basis of the collagen defect in OI resulting in odontoblast dysfunction, which produces a distinct phenotype and one that is different from that in bone.     

Odontoblast dysfunction in osteogenesis imperfecta: an LM,SEM, and ultrastructural study

The inherited dentin defect dentinogenesis imperfecta (DI), while clinically obvious in osteogenesis imperfecta (OI) Types IB and IC, II, III, and IVB, is now thought to be present in all children with OI, in a continuum from minimal to severe dentin pathology. This collaborative study further clarifies the structural and ultrastructural dentin changes in the teeth of OI children with clinically obvious DI, and attempts to explain these in terms of odontoblast dysfunction. Collaborative studies were carried out in Melbourne, Australia, and Strasbourg, France, using light and polarized-light microscopy, scanning and transmission electron microscopy (SEM, TEM), selected-area diffraction (SAD), and x-ray spectroscopy (EDX). These showed structurally normal enamel (but containing long and broad lamellae) and a normally scalloped dentino-enamel junction (DEJ), but severe pathologic changes in the dentin. An initial narrow band of normal-appearing dentin tubules (including the mantle layer) ceased abruptly and was replaced by a wavelike laminar zone parallel to the DEJ with occluded tubules. Multiple parallel channels of 5-10 microns diameter were present at right angles to the DEJ indenting this zone, some terminating in retro-curved "processes." The abnormal dentin containing these channels almost completely occluded the pulp chamber. The structural and ultrastructural changes seen can be explained on the basis of the collagen defect in OI resulting in odontoblast dysfunction, which produces a distinct phenotype and one that is different from that in bone.     

Type 1 collagenopathy presenting with a Russell-Silver phenotype

Osteogenesis imperfecta (OI) is a heterogeneous group of inherited disorders of bone formation, resulting in low bone mass and an increased propensity to fracture. It exhibits a broad spectrum of clinical severity, ranging from multiple fractures in utero and perinatal death, to normal adult stature and low fracture incidence. Extra-skeletal features of OI include blue sclera, hearing loss, skin hyperlaxity, joint hyperextensibility, and dentinogenesis imperfecta. The proα1(I) and proα2(I) chains of collagen 1 are encoded by the COL1A1 and COL1A2 genes, respectively; quantitative or qualitative defects in type I collagen synthesis usually manifest as types of OI or some sub-types of EDS. The majority of patients (about 90%) with a clinical diagnosis of OI have a mutation in the COL1A1 or COL1A2 genes, which shows an autosomal dominant pattern of inheritance. Six other genes, CRTAP, LEPRE1, FKBP10, PP1B, SP7/Osterix (OSX), and SERPINH1, are associated with autosomal recessive forms of OI. However, other, rare phenotypes have also been described. There are many differential diagnoses of the short, syndromic child, including chromosomal, single gene, and multifactorial causes. However, one condition of particular relevance in the context of this report is the Russell-Silver syndrome (RSS). As originally described, the RSS is a very specific condition. However, it has subsequently become an umbrella term for a heterogeneous group of conditions presenting with short stature and triangular shape to the face. A significant proportion of these are now believed to be due to imprinting defects at 11p15. However, the cause in many cases remains unknown. We describe two cases with a phenotypic overlap between OI and RSS who both have COL1A1 mutations. Thus, a type 1 collagenopathy should be considered in the differential diagnosis of syndromic short stature.     

Analysis of craniofacial development in children with hypohidrotic ectodermal dysplasia

Ectodermal dysplasias (ED) are a heterogeneous group of inheritable disorders characterized by abnormal development of embryologic ectoderm derivatives. The purposes of this study were to: 1) create baseline cephalometric norms for male children with ED; 2) assess craniofacial growth and development in hypohidrotic ED male children with severe hypodontia, compared with non-ED children with class I dental relationships; 3) compare the craniofacial morphology of titanium dental implant-treated ED males with non-implant-treated ED males; and 4) correlate the severity of hypodontia to craniofacial dysmorphology. Cephalometric radiographs of class I individuals and implant-treated and nontreated ED groups were used to evaluate craniofacial morphology. Traditional cephalometric landmarks and measurements were used to compare groups using the generalized estimate equation analysis. Age, gender, and the number of permanent maxillary teeth present had a significant (P =.01) explanatory relationship with the craniofacial measures when comparing untreated ED children to norms. Mean craniofacial differences between ED and non-ED children still existed when the explanatory effects of these variables were controlled, indicating dysmorphology in several craniofacial structures (e.g., cranial base, mandibular length). The number of missing maxillary permanent teeth was significantly related with craniofacial dysmorphology in the ED population. Craniofacial morphology did not differ significantly between implant-treated and nontreated ED children, suggesting that treatment with intraosseous dental implants, as applied in this population, did not rescue normal craniofacial growth and development.     

Osteogenesis Imperfecta Type VI with Severe Bony Deformities Caused by Novel Compound Heterozygous Mutations in SERPINF1

Osteogenesis imperfecta (OI) comprises a heterogeneous group of disorders characterized by bone fragility, frequent fractures, and low bone mass. Dominantly inherited COL1A1 or COL1A2 mutations appear to be causative in the majority of OI types, but rare recessively inherited genes have also been reported. Recently, SERPINF1 has been reported as another causative gene in OI type VI. To date, only eight SERPINF1 mutations have been reported and all are homozygous. Our patient showed no abnormalities at birth, frequent fractures, osteopenia, and poor response on pamidronate therapy. At the time of her most recent evaluation, she was 8 yr old, and could not walk independently due to frequent lower-extremity fractures, resulting in severe deformity. No clinical signs were seen of hearing impairment, blue sclera, or dentinogenesis imperfecta. In this study, we describe the clinical and radiological findings of one Korean patient with novel compound heterozygous mutations (c.77dupC and c.421dupC) of SERPINF1.     

Osteogenesis imperfecta: Mosaicism and refinement of the genotype‐phenotype map in OI type III

Non‐lethal OI III (OMIM 259420) is caused by structural aberrations of collagen I. We report four novel glycine substitutions, one in the a1(I) chain of collagen I (G688S) and three in the a2(I) chain (G241D, G247C, G883V). In each of two families (G241D and G883V), we found parental mosaicism for the substitution explaining recurrence and intrafamilial variability of OI. The G247C and the G883V are the most N‐terminally and C‐terminally, respectively, placed cysteine and valine substitutions reported. The new substitutions add important information to the genotype‐phenotype map and in particular the importance of a‐chain stoichiometry is underlined. Data regarding the G688S substitution may suggest a different effect of the two a‐chains in the development of dentinogenesis imperfecta (DI). Hum Mutat 13:503, 1999. © 1999 Wiley‐Liss, Inc.     

Craniofacial features in osteogenesis imperfecta: a cephalometric study

Osteogenesis imperfecta (OI) is a heterogeneous group of connective tissue diseases that mainly manifest as bone fragility and skeletal deformity. In most families it segregates as a dominant trait and results from mutations in type I collagen genes. In this study we analyzed the size and form of the bony structures in heads of 59 consecutive patients with OI types I, III, or IV (Sillence classification), using lateral radiographs. Paired controls were matched for gender and age. The purpose was to obtain baseline information of craniofacial development in OI patients that have not received bisphosphonate treatment. In OI type I we found smaller than normal linear measurements, indicating a general growth deficiency, but no remarkable craniofacial deformity. In OI types III and IV, the growth impairment was pronounced, and the craniofacial form was altered as a result of differential growth deficiency and bending of the skeletal head structures. We found strong support both for an abnormally ventral position of the sella region due to bending of the cranial base, and for a closing mandibular growth rotation. Vertical underdevelopment of the dentoalveolar structures and the condylar process were identified as the main reasons for the relative mandibular prognathism in OI. Despite of the widespread intervention with bisphosphonates, the facial growth impairment will probably remain characteristic for many OI patients, and their orthodontic treatment should be further developed.     

Emergence of permanent teeth among the meiteis of Manipur,India

To estimate the time and sequence of emergence of the first 28 permanent teeth in rural Meiteis of Manipur, 440 children 5–14 years of age were examined. Median tooth emergence times were earlier in females than males. The first molar was highly variable in its emergence time in both sexes. With the exception of premolars, mandibular teeth emerged earlier than maxillary teeth. Although no definite pattern was found in bilateral differences, left maxillary teeth and right mandibular teeth emerged slightly earlier in females and males, respectively. There was no clear sex difference in the sequence of permanent tooth emergence. The quiescent period between the first and second phases of tooth emergence was more apparent in the mandible than in the maxilla and occurred between the lateral incisor and first premolar in both jaws and sexes. The Meiteis displayed earlier emergence compared to other populations within India. The findings of this study support earlier reports that socioeconomic conditions do not significantly influence permanent tooth emergence; the chief controlling factor is most likely genetic. © 1994 Wiley-Liss, Inc.     

常染色体隐性遗传性成骨不全症的分子遗传学研究进展

成骨不全症(osteogenesis imperfecta,OI)又称脆骨症,由于遗传缺陷而引起Ⅰ型胶原结构或功能异常,表现为全身骨骼等结缔组织异常.临床特点是多发性骨折,同时可伴有巨头畸形、蓝巩膜、耳聋、牙齿改变和脊柱后侧凸等.成骨不全症不仪临床表型变异度大,而且遗传异质性高,以常染色体显件或隐性遗传方式传递,本文就常染色体隐性遗传性成骨不全症的分子遗传学研究进展加以综述.     

常染色体隐性遗传性成骨不全症的分子遗传学研究进展

成骨不全症(osteogenesis imperfecta,OI)又称脆骨症,由于遗传缺陷而引起Ⅰ型胶原结构或功能异常,表现为全身骨骼等结缔组织异常.临床特点是多发性骨折,同时可伴有巨头畸形、蓝巩膜、耳聋、牙齿改变和脊柱后侧凸等.成骨不全症不仪临床表型变异度大,而且遗传异质性高,以常染色体显件或隐性遗传方式传递,本文就常染色体隐性遗传性成骨不全症的分子遗传学研究进展加以综述.