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Journal of Molecular Histology Dec 2019Mutations in the gene encoding family with sequence similarity 20, member A (FAM20A) caused amelogenesis imperfecta (AI), in humans. However, the roles of FAM20A in...
Mutations in the gene encoding family with sequence similarity 20, member A (FAM20A) caused amelogenesis imperfecta (AI), in humans. However, the roles of FAM20A in amelogenesis and dentinogenesis are poorly understood. In this study, we generated a Fam20a knockout (Sox2-Cre;Fam20a) mouse model by crossing Fam20a mice with Sox2-Cre transgenic mice, in which Fam20a was ablated in both dental epithelium and dental mesenchyme. We found that these mice developed an enamel phenotype that resembles human AI associated with FAM20A mutations, but did not have apparent dentin defects. The secretory stage ameloblasts in the mandibular incisors from the Sox2-Cre;Fam20a mice were shorter and detached from the enamel matrix, and subsequently lost their polarity, became disorganized and formed numerous spherical extracellular matrices in place of normal enamel. At the molecular level, the Sox2-Cre;Fam20a mice displayed dramatically reduced expression levels of the genes encoding the enamel matrix proteins, but unaltered levels of the genes encoding the dentin matrix proteins. Moreover, Fam20a ablation resulted in a great decrease in FAM20C protein level, but it did not alter the intracellular localization of FAM20C protein in ameloblasts and odontoblasts. These results indicate that FAM20A is essential for amelogenesis, but is dispensable for dentinogenesis.
Topics: Ameloblasts; Amelogenesis; Amelogenesis Imperfecta; Animals; Calcium-Binding Proteins; Dental Enamel; Dental Enamel Proteins; Dentin; Dentinogenesis; Extracellular Matrix Proteins; Humans; Mice, Knockout; Mice, Transgenic; Mutation; Odontoblasts; SOXB1 Transcription Factors
PubMed: 31667691
DOI: 10.1007/s10735-019-09851-x -
Frontiers in Genetics 2019Osteogenesis imperfecta (OI) is a hereditary bone disorder caused by defects of type I collagen. Although up to 90% of patients harbor pathogenic variants in the gene,...
Osteogenesis imperfecta (OI) is a hereditary bone disorder caused by defects of type I collagen. Although up to 90% of patients harbor pathogenic variants in the gene, which codes for collagen α1/2 chains, the spectrum of OI genotypes may differ between populations, and there is academic controversy around OI genotype-phenotype correlations. In the current study, 94 Ukrainian OI families were interviewed. Clinical and genealogical information was collected from patients in spoken form, and their phenotypes were described. To identify the spectrum of collagen I pathogenic variants, mutational analysis with Sanger sequencing was performed on the youngest affected individual of every family. Of the 143 patients investigated, 67 (46.85%) had type I OI, 24 (16.78%) had type III, 49 (34.27%) had type IV, and III (2.10%) had type V. The mean number of fractures suffered per patient per year was 1.32 ± 2.88 (type I 0.50 ± 0.43; type III 3.51 ± 6.18; type IV 1.44 ± 1.77; and type 5 0.77 ± 0.23). 87.23% of patients had skeletal deformations of different severity. Blue sclera, dentinogenesis imperfecta, and hearing loss were present in 87%, 55%, and 22% of patients, respectively. pathogenic variants were harbored by 60 patients (63.83%). 27 pathogenic variants are described herein for the first time. The majority of the pathogenic variants were located in the gene (76.19%). Half (49.21%) of the pathogenic variants were represented by structural variants. OI phenotype severity was highly correlated with type of collagen I defect. The current article presents an analysis of the clinical manifestations and mutational spectrum of 94 Ukrainian OI families with 27 novel pathogenic variants. It is hoped that this data and its analysis will contribute toward the increased understanding of the phenotype development and genetics of the disorder.
PubMed: 31447884
DOI: 10.3389/fgene.2019.00722 -
Molecular Genetics & Genomic Medicine Aug 2019Osteogenesis imperfecta (OI) is a clinically heterogeneous disease characterized by extreme skeletal fragility. It is caused by mutations in genes frequently affecting...
BACKGROUND
Osteogenesis imperfecta (OI) is a clinically heterogeneous disease characterized by extreme skeletal fragility. It is caused by mutations in genes frequently affecting collagen biosynthesis. Mutations in CREB3L1 encoding the ER stress transducer OASIS are very rare and are only reported in pediatric patients. We report a large family with a novel CREB3L1 mutation, with severe adult clinical presentation.
METHODS
Clinical examination was performed on the family members. Next generation sequencing was performed for the causative genes for OI. The mutation was confirmed in other family members with Sanger sequencing.
RESULTS
A novel homozygous mutation in CREB3L1 was identified in the three affected patients. The parents and siblings who carry the mutation in heterozygous state were clinically unaffected. The three affected siblings, who were reported to have been born healthy, presented very severe progressive skeletal malformations and joint contractures but absence of common OI characteristics including blue sclerae, deafness, and dentinogenesis imperfecta. Resorption of a part of the humerus presumably associated with fracture nonunion and pseudarthrosis.
CONCLUSION
We report a novel homozygous CREB3L1 mutation in a large Indonesian family; the homozygous affected members have survived to adulthood and they present a more severe phenotype than previously reported, expanding the clinical spectrum of OI for this gene.
Topics: Adult; Cyclic AMP Response Element-Binding Protein; DNA Mutational Analysis; High-Throughput Nucleotide Sequencing; Homozygote; Humans; Indonesia; Male; Mutation; Nerve Tissue Proteins; Osteogenesis Imperfecta; Severity of Illness Index
PubMed: 31207160
DOI: 10.1002/mgg3.823 -
Genes & Diseases Jun 2019Osteogenesis imperfecta (OI) is mainly characterized by bone fragility and Ehlers-Danlos syndrome (EDS) by connective tissue defects. Mutations in or can lead to both...
Osteogenesis imperfecta (OI) is mainly characterized by bone fragility and Ehlers-Danlos syndrome (EDS) by connective tissue defects. Mutations in or can lead to both syndromes. OI/EDS overlap syndrome is mostly caused by helical mutations near the amino-proteinase cleavage site of type I procollagen. In this study, we identified a Thai patient having OI type III, EDS, brachydactyly, and dentinogenesis imperfecta. His dentition showed delayed eruption, early exfoliation, and severe malocclusion. For the first time, ultrastructural analysis of the tooth affected with OI/EDS showed that the tooth had enamel inversion, bone-like dentin, loss of dentinal tubules, and reduction in hardness and elasticity, suggesting severe developmental disturbance. These severe dental defects have never been reported in OI or EDS. Exome sequencing identified a novel heterozygous glycine substitution, c.3296G > A, p.Gly1099Glu, in exon 49 of . Three patients with mutations in the exon 49 of were previously reported to have OI with brachydactyly and intracranial hemorrhage. Notably, two of these three patients did not show hyperextensible joints and hypermobile skin, while our patient at the age of 5 years had not developed intracranial hemorrhage. Here, we demonstrate that the novel glycine substitution in the carboxyl region of alpha2(I) collagen triple helix leads to OI/EDS with brachydactyly and severe tooth defects, expanding the genotypic and phenotypic spectra of OI/EDS overlap syndrome.
PubMed: 31193991
DOI: 10.1016/j.gendis.2019.03.001 -
Journal of Dental Research Jul 2019Dentin sialophosphoprotein (DSPP) is an extracellular matrix protein highly expressed by odontoblasts in teeth. DSPP mutations in humans may cause dentinogenesis...
Dentin sialophosphoprotein (DSPP) is an extracellular matrix protein highly expressed by odontoblasts in teeth. DSPP mutations in humans may cause dentinogenesis imperfecta (DGI), an autosomal dominant dentin disorder. We recently generated a mouse model (named " mice") that expressed a mutant DSPP in which the proline residue at position 19 was replaced by a leucine residue. We found that the and mice at a younger age displayed a tooth phenotype resembling human DGI type III characterized by enlarged dental pulp chambers, while the teeth of older and mice had smaller dental pulp chambers mimicking DGI type II. The teeth of and mice had a narrower pulp chamber roof predentin layer, thinner pulp chamber roof dentin, and thicker pulp chamber floor dentin. In addition, these mice also had increased enamel attrition, accompanied by excessive deposition of peritubular dentin. Immunohistochemistry, in situ hybridization, and real-time polymerase chain reaction analyses showed that the odontoblasts in both and mice had reduced DSPP expression, compared to the wild-type mice. We also observed that the levels of DSPP expression were much higher in the roof-forming odontoblasts than in the floor-forming odontoblasts in the wild-type mice and mutant mice. Moreover, immunohistochemistry showed that while the immunostaining signals of dentin sialoprotein (N-terminal fragment of DSPP) were decreased in the dentin matrix, they were remarkably increased in the odontoblasts of the and mice. Consistently, our in vitro studies showed that the secretion of the mutant DSPP was impaired and accumulated within endoplasmic reticulum. These findings suggest that the dental phenotypes of the mutant mice were associated with the intracellular retention of the mutant DSPP in the odontoblasts of the DSPP-mutant mice.
Topics: Animals; Dentin; Dentinogenesis; Dentinogenesis Imperfecta; Disease Models, Animal; Extracellular Matrix Proteins; Humans; Mice; Odontoblasts; Phosphoproteins; Sialoglycoproteins
PubMed: 31173534
DOI: 10.1177/0022034519854029 -
Genetics and Molecular Biology 2019Treatment of moderate and severe forms of osteogenesis imperfecta (OI) with cyclic pamidronate at the Reference Center for OI Treatment in Southern Brazil was studied. A...
Treatment of moderate and severe forms of osteogenesis imperfecta (OI) with cyclic pamidronate at the Reference Center for OI Treatment in Southern Brazil was studied. A retrospective cohort study was conducted from 2002 to 2012. Data were obtained during inpatient (drug infusion) and outpatient care. Clinical data, including the presence of blue sclerae, dentinogenesis imperfecta, history and site of the fractures, biochemical data, including calcium, phosphorus, and alkaline phosphatase levels, were systematically collected. Bone mineral density (BMD) was measured using dual energy X-ray absorptiometry (DXA). Forty-five patients (26 females) were included in the study, and the age of the patients at the time of diagnosis ranged from 1 to 144 months, with a median age (p25-p75) of 38 (5-96) months. Most cases presented OI-4 (51.1%), and the median age of the patients at the start of treatment was 3.3 years (25-75 percentiles: 0.5 - 8.7 years). Twenty-four patients (54.5%) had some adverse events or intercurrences during treatment, and the treatment compliance mean was 92.3% (± 10.7). The treatment with intravenous pamidronate has shown to be safe, well-tolerated, and effective in regard to the improvement of BMD and the reduction of the number of fractures in children and adolescents with OI.
PubMed: 31067290
DOI: 10.1590/1678-4685-GMB-2018-0097 -
BDJ Open 2019The maxillofacial and dental manifestations of Osteogenesis imperfecta (OI) have significant implications in terms of management. Although the occurrence of abnormal...
BACKGROUND
The maxillofacial and dental manifestations of Osteogenesis imperfecta (OI) have significant implications in terms of management. Although the occurrence of abnormal dentine in some forms of OI is well documented, there is scant information on the association of abnormal dentine in the Black African persons with phenotypic OI III and genotypic OI XI in South Africa.
METHODS
This was a cross-sectional analytic study. A series of 64 Black South African individuals with a confirmed phenotypic diagnosis of OI III, ages ranging from 3 months to 29 years, were assessed clinically, radiographically, and at a molecular level.
RESULTS
A total number of 64 saliva samples were analyzed and 3 DNA variations were identified in exon 5 of the gene. The homozygous mutation, c.[831dupC]; [831dupC], was identified in 23 affected persons who had no clinically obvious features of DI in their primary and secondary teeth. Radiologically, mild features of DI were evident in 10 persons in whom radiographic images were obtained and were given a Clinical-radiological score of 2. A compound heterozygous mutation, c. [831delC]; [831dupC], was identified in three siblings. An intraoral examination of these affected persons revealed no clinically apparent features of DI in their primary and secondary teeth. Due to the lack of radiological facilities, the presence or absence of DI could not be confirmed or negated. A second compound heterozygous mutation, c.[831dupC]; [1400-4C>G], was identified in a female of 29 years belonging to the Xhosa linguistic group. Her teeth appeared clinically normal but it was not possible to obtain radiographs. In 37 affected individuals, no disease-causing mutations were identified.
CONCLUSION
Black African individuals in SA with the homozygous mutation in the gene have clinically unaffected teeth yet exhibited radiographic features of DI to varying degrees. This characterization is suggestive of a relationship between the genetic abnormality and the clinical manifestations of DI. The authors suggest that this diagnosis must include teeth that are clinically and/or radiologically aberrant, and should not exclude the presence of other, milder, dentinal aberrations associated with OI. There was no correlation between severity of OI and DI in this cohort of individuals.
PubMed: 30993005
DOI: 10.1038/s41405-019-0014-z -
Frontiers in Physiology 2019mTORC1 signaling plays an important role in extracellular and intracellular signals, including growth factors, nutrients, energy metabolism, and stress. However, the...
mTORC1 signaling plays an important role in extracellular and intracellular signals, including growth factors, nutrients, energy metabolism, and stress. However, the functional role of mTORC1 in dentinogenesis is unknown. To study the role of Raptor/mTORC1 in dentinogenesis, an Raptor; Osx-Cre (Rap-Osx) mouse, in which Raptor was conditionally deleted in odontoblasts and dental mesenchymal cells, was generated, and postnatal tooth development was compared between Rap-Osx mice and control littermates. Rap-Osx mice presented a phenotype known as dentinogenesis imperfecta and had smaller tooth volume, a thinner dentin layer and a larger pulp chamber. The proliferation and differentiation of odontoblasts/preodontoblasts were attenuated in mutant mice, which was likely responsible for the defects in dentinogenesis. Raptor/mTORC1-pS6K1 signaling was inactivated during tooth development in Rap-Osx mice, whereas it was activated in control mice. These results indicate that Raptor/mTORC1 plays a critical role in dentinogenesis promoting odontoblasts/preodontoblasts proliferation and differentiation. Raptor/mTORC1 might regulate tooth development through the pS6K1 signaling pathway.
PubMed: 30984011
DOI: 10.3389/fphys.2019.00250 -
The Journal of Clinical Pediatric... 2019Dentinogenesis Imperfecta type II (DI2), also known as hereditary opalescent dentin, is one of the most common genetic disorders affecting the structure of dentin, not... (Review)
Review
Dentinogenesis Imperfecta type II (DI2), also known as hereditary opalescent dentin, is one of the most common genetic disorders affecting the structure of dentin, not related with osteogenesis imperfecta, which involves both primary and permanent dentitions. The purpose of this article is to perform a scoping review of the published peer-reviewed literature (1986-2017) on DI2 management in children and to outline the most relevant clinical findings extracted from this review. Forty four articles were included in the present scoping review. According to the extracted data, the following are the most important tasks to be performed in clinical pediatric dentistry: to re-establish the oral mastication, esthetics, and speech, and the development of vertical growth of alveolar bone and facial muscles; to reduce the tendency to develop caries, periapical lesions and pain; to preserve vitality, form, and size of the dentition; to avoid interfering with the eruption process of permanent teeth; to decrease the risk of tooth fractures and occlusion disturbances; to return the facial profile to a more normal appearance; and to prevent or treat possible temporomandibular joint problems. Therefore, Pediatric Dentists should bear in mind that early diagnosis and treatment, together a long-term follow-up of DI2 in children, continue to be the best approaches for achieving enhanced patient psychological well-being and, in consequence, their quality of life.
Topics: Child; Child, Preschool; Dental Care for Children; Dentinogenesis Imperfecta; Dentition, Permanent; Esthetics, Dental; Humans; Quality of Life
PubMed: 30964718
DOI: 10.17796/1053-4625-43.3.1 -
European Journal of Human Genetics :... Jul 2019Osteogenesis imperfecta (OI) is a rare genetic disorder of the connective tissue and 90% of cases are due to dominant mutations in COL1A1 and COL1A2 genes. To increase... (Clinical Trial)
Clinical Trial
Osteogenesis imperfecta (OI) is a rare genetic disorder of the connective tissue and 90% of cases are due to dominant mutations in COL1A1 and COL1A2 genes. To increase OI disease knowledge and contribute to patient follow-up management, a homogeneous Italian cohort of 364 subjects affected by OI types I-IV was evaluated. The study population was composed of 262 OI type I, 24 type II, 39 type III, and 39 type IV patients. Three hundred and nine subjects had a type I collagen affecting function mutations (230 in α1(I) and 79 in α2(I)); no disease-causing changes were noticed in 55 patients. Compared with previous genotype-phenotype OI correlation studies, additional observations arose: a new effect for α1- and α2-serine substitutions has been pointed out and heart defects, never considered before, resulted associated to quantitative mutations (P = 0.043). Moreover, some different findings emerged if compared with previous literature; especially, focusing the attention on the lethal form, no association with specific collagen regions was found and most of variants localized in the previously reported "lethal clusters" were causative of OI types I-IV. Some discrepancies have been highlighted also considering the "50-55 nucleotides rule," as well as the relationship between specific collagen I mutated region and the presence of dentinogenesis imperfecta and/or blue sclera. Despite difficulties still present in defining clear rules to predict the clinical outcome in OI patients, this study provides new pieces for completing the puzzle, also thanks to the inclusion of clinical signs never considered before and to the large number of OI Italian patients.
Topics: Adult; Amino Acid Substitution; Child, Preschool; Collagen Type I; Collagen Type I, alpha 1 Chain; Female; Genotype; Humans; Infant; Italy; Male; Mutation, Missense; Osteogenesis Imperfecta; Phenotype; Young Adult
PubMed: 30886339
DOI: 10.1038/s41431-019-0373-x