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Thesis (Ph. D.)--University of Missouri-Columbia, 2006. / Title from title screen of research.pdf file (viewed on December 22, 2006). The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. "May 2006" Vita. Includes bibliographical references.

Family with sequence similarity 20 (FAM20) consists of three members: FAM20A, FAM20B and FAM20C. Mutations in FAM20 family have been linked to developmental disorders involving bones, cartilage and teeth. FAM20A mutations in humans are associated with amelogenesis imperfecta with gingival fibromatosis and enamel renal syndrome. Fam20a knockout (KO) mouse showed growth retardation. The aim of this study was to characterize the skeletal and dental phenotypes using Fam20a KO mouse. Our results showed that body size and bone length of KO mice were smaller than those of WT. The microcomputed tomography (μCT) analyses of trabecular and cortical bones in KO displayed lower bone volume, thinner trabeculae and thinner bone cortex as compared to WT. Histological examination of KO growth plate demonstrated disorganized chondrocyte zones and extended hypertrophic zone. qRT-PCR results showed downregulation of several osteoblast differentiation markers in KO long bone. Immunohistochemical examination demonstrated reduced chondrocyte proliferation, apoptosis and increased collagen X expression in KO growth plate. Our data showed a lower number of osteoblasts and osteoclasts in KO as compared to WT. In vitro study, Fam20a KO showed a lower number of bone marrow stromal cells and osteoprogenitors. In vitro mineralization was impaired in KO osteoblasts. Fam20a KO had hypoplastic enamel, delayed tooth eruption and gingival overgrowth. The µCT results demonstrated that enamel in Fam20a KO was not fully mineralized and enamel matrix was detached from dentin. Scanning electron microscopy displayed absence of decussation patterns in Fam20a KO enamel. Histological examination of maxillary first molar at differentiation stage showed no difference between WT and KO. At the secretory stage, Fam20a KO ameloblasts were short and non-polarized as compared to WT. Immunohistochemical analysis showed diffuse staining pattern of amelogenin in Fam20a KO first molar compared to WT. Western blot analysis demonstrated that amelogenin proteolytic process was impaired in KO and showed slower migration pattern of MMP20. In conclusion, endochondral ossification defects and reduced number of osteoblasts and their precursors led to the bone phenotype in Fam20a KO. Amelogenin processing defects caused amelogenesis imperfecta phenotype in KO. Our study indicated that Fam20a plays a role in skeletal development and amelogenesis.

Amelogenesis imperfecta (AI) is a genetically determined enamel defect characterized by genetic and clinical heterogeneity . The prevalence and incidence of AI were established in the county of Västerbotten, northern Sweden, in 3-19-yr-olds born 1963-79, as were the mode of inheritance and clinical manifestation of AI. The distribution of the inorganic component in the enamel of AI teeth was studied as well as the surface morphology and other morphological details, and the findings were correlated to genetic and clinical data. AI was diagnosed in 79 children and adolescents (index cases). The prevalence in the study population was 1.4: 1 000. The mean yearly incidence 1963-79 was 1.3:1 000. The inheritance patterns for AI were established in 78 index cases from 51 families. Pedigree and segregation analyses suggested autosomal dominant (AD) inheritance in 3 3 families, autosomal recessive (AR) in six families, and X- linked recessive in two families; in ten families only sporadic cases were found. In one of the families with an AD inheritance pattern, X-linked dominant was a possible alternative. Examination of the families of the 78 index cases revealed 107 new cases of AI. The hypoplastic form was seen in 72% of all diagnosed cases and the hypomineralization form in 28% of the cases. A further classification of the clinical manifestations led to the identification of eight clinical variants. In 3 3 of the 51 families the same clinical variant was found in all affected members. In eight families affected members were assigned to different clinical variants. In three families with an X-linked inheritance pattern for AI, the clinical manifestation differed between women and men due to lyo- nization. Among the remaining five families, with an AD inheritance pattern for AI, variants clinically characterized by hypoplasia as well as variants characterized by hypomineralization were found in three families; in the other two families the clinical manifestation varied within the same main form of AI, i.e. hypoplasia or hypomineralization. Hypoplasia as well as hypomineralization were observed microradiographically in the enamel of most of the examined teeth. These findings were supported by scanning electron microscopy (SEM). Both clinically and microradiographically as well as by SEM, similar variants of AI were found as AD and AR traits and/or among the sporadic cases. In the families with AI as an X-linked trait the genetic hypothesis was confirmed by the clinical, microradiographic and scanning electron microscopic findings. / <p>S. 1-46: sammanfattning, s. 47-134: 5 uppsatser</p> / digitalisering@umu

Diss. (sammanfattning) Stockholm : Karolinska institutet, 2007. / Härtill 5 uppsatser.

A Osteogênese Imperfeita (OI) é caracterizada por fragilidade óssea e susceptibilidade a fraturas. As complicações da patologia podem afetar o desenvolvimento físico e motor, comprometendo as habilidades funcionais, o nível da marcha e a independência do indivíduo. Objetivo: Avaliar as características clínico-funcionais de crianças e adolescentes com Osteogênese Imperfeita (OI). Métodos: Estudo transversal no qual foram avaliados sujeitos de ambos os gêneros com idade entre 0 e 18 anos e diagnóstico de OI, em tratamento no CROI-RS. Os dados clínicos e funcionais foram coletados através de fichas específicas e avaliação funcional. Foram avaliados aspectos relacionados à presença de fraturas e deformidades ósseas, habilidade da marcha, força muscular e amplitude de movimento articular. A densidade mineral óssea (DMO) foi mensurada através do Dual Energy X-Ray Absoptometry (DEXA). O nível de significância adotado foi de 5% (p≤0,05). Resultados: Encontramos diferença significativa na ocorrência de fraturas, presença de deformidades ósseas, uso de haste intramedular, baixa densidade mineral óssea, tratamento medicamentoso e aspectos relacionados à marcha comparando OI tipo I, III e IV. As formas mais graves de OI (tipo III e IV) apresentaram fraturas nos primeiros meses de vida, maior deformidade óssea. Associação inversa entre amplitude de movimento articular geral e o nível da marcha e uma associação direta com idade de início de marcha, o número total de fraturas e a presença de deformidades ósseas. Encontrou-se uma associação direta entre a força muscular geral e o nível da marcha e uma associação inversa com a idade de início de marcha e presença de deformidades ósseas. Conclusão: Estes dados sugerem que as características clínico-funcionais variam de acordo com os tipos de OI. Nas formas moderada e grave de OI há maior limitação funcional influenciada pelo número de fraturas e presença de deformidades ósseas afetando negativamente o nível da marcha. / Osteogenesis Imperfecta (OI) is characterized by bone fragility and susceptibility to fractures. Complications of the disease can affect the physical and motor development, compromising the functional skills, level of gait and independence of the individual. Objective: To evaluate the clinical and functional features of children and adolescents with OI. Methods: A cross-sectional study which evaluated subjects of both genders aged between 0 and 18 years attended in the Reference Center for Treatment of OI of Rio Grande do Sul (CROI-RS). Clinical and functional data were evaluated through specific tokens and functional assessment. We evaluated aspects related to the presence of fractures and bone deformities, gait ability, muscle strength, joint range of motion and use of intramedullary rod. Bone mineral density (BMD) was measured by Dual Energy X-Ray Absoptometry (DEXA). The level of significance was set at 5% (p ≤ 0.05). Results: We found significant differences in the occurrence of fractures, presence of bone deformities, use of intramedullary rod, bone mineral density, drug therapy and aspects related to gait comparing OI types I, III and IV. The age of gait acquisition showed a direct association with overall joint range of motion and an inverse relationship with overall muscle strength. The level of ambulation was directly associated with overall muscle strength and inversely associated with overall joint range of motion. Conclusion: Our findings confirm that clinical and functional features vary according to OI type. Moderate and severe forms of OI are associated with greater functional limitation, influenced by fractures in early life, number of fractures and the presence of bone deformities, which negatively affect the acquisition and level of ambulation.

A Osteogênese Imperfeita (OI) é caracterizada por fragilidade óssea e susceptibilidade a fraturas. As complicações da patologia podem afetar o desenvolvimento físico e motor, comprometendo as habilidades funcionais, o nível da marcha e a independência do indivíduo. Objetivo: Avaliar as características clínico-funcionais de crianças e adolescentes com Osteogênese Imperfeita (OI). Métodos: Estudo transversal no qual foram avaliados sujeitos de ambos os gêneros com idade entre 0 e 18 anos e diagnóstico de OI, em tratamento no CROI-RS. Os dados clínicos e funcionais foram coletados através de fichas específicas e avaliação funcional. Foram avaliados aspectos relacionados à presença de fraturas e deformidades ósseas, habilidade da marcha, força muscular e amplitude de movimento articular. A densidade mineral óssea (DMO) foi mensurada através do Dual Energy X-Ray Absoptometry (DEXA). O nível de significância adotado foi de 5% (p≤0,05). Resultados: Encontramos diferença significativa na ocorrência de fraturas, presença de deformidades ósseas, uso de haste intramedular, baixa densidade mineral óssea, tratamento medicamentoso e aspectos relacionados à marcha comparando OI tipo I, III e IV. As formas mais graves de OI (tipo III e IV) apresentaram fraturas nos primeiros meses de vida, maior deformidade óssea. Associação inversa entre amplitude de movimento articular geral e o nível da marcha e uma associação direta com idade de início de marcha, o número total de fraturas e a presença de deformidades ósseas. Encontrou-se uma associação direta entre a força muscular geral e o nível da marcha e uma associação inversa com a idade de início de marcha e presença de deformidades ósseas. Conclusão: Estes dados sugerem que as características clínico-funcionais variam de acordo com os tipos de OI. Nas formas moderada e grave de OI há maior limitação funcional influenciada pelo número de fraturas e presença de deformidades ósseas afetando negativamente o nível da marcha. / Osteogenesis Imperfecta (OI) is characterized by bone fragility and susceptibility to fractures. Complications of the disease can affect the physical and motor development, compromising the functional skills, level of gait and independence of the individual. Objective: To evaluate the clinical and functional features of children and adolescents with OI. Methods: A cross-sectional study which evaluated subjects of both genders aged between 0 and 18 years attended in the Reference Center for Treatment of OI of Rio Grande do Sul (CROI-RS). Clinical and functional data were evaluated through specific tokens and functional assessment. We evaluated aspects related to the presence of fractures and bone deformities, gait ability, muscle strength, joint range of motion and use of intramedullary rod. Bone mineral density (BMD) was measured by Dual Energy X-Ray Absoptometry (DEXA). The level of significance was set at 5% (p ≤ 0.05). Results: We found significant differences in the occurrence of fractures, presence of bone deformities, use of intramedullary rod, bone mineral density, drug therapy and aspects related to gait comparing OI types I, III and IV. The age of gait acquisition showed a direct association with overall joint range of motion and an inverse relationship with overall muscle strength. The level of ambulation was directly associated with overall muscle strength and inversely associated with overall joint range of motion. Conclusion: Our findings confirm that clinical and functional features vary according to OI type. Moderate and severe forms of OI are associated with greater functional limitation, influenced by fractures in early life, number of fractures and the presence of bone deformities, which negatively affect the acquisition and level of ambulation.

A Osteogênese Imperfeita (OI) é caracterizada por fragilidade óssea e susceptibilidade a fraturas. As complicações da patologia podem afetar o desenvolvimento físico e motor, comprometendo as habilidades funcionais, o nível da marcha e a independência do indivíduo. Objetivo: Avaliar as características clínico-funcionais de crianças e adolescentes com Osteogênese Imperfeita (OI). Métodos: Estudo transversal no qual foram avaliados sujeitos de ambos os gêneros com idade entre 0 e 18 anos e diagnóstico de OI, em tratamento no CROI-RS. Os dados clínicos e funcionais foram coletados através de fichas específicas e avaliação funcional. Foram avaliados aspectos relacionados à presença de fraturas e deformidades ósseas, habilidade da marcha, força muscular e amplitude de movimento articular. A densidade mineral óssea (DMO) foi mensurada através do Dual Energy X-Ray Absoptometry (DEXA). O nível de significância adotado foi de 5% (p≤0,05). Resultados: Encontramos diferença significativa na ocorrência de fraturas, presença de deformidades ósseas, uso de haste intramedular, baixa densidade mineral óssea, tratamento medicamentoso e aspectos relacionados à marcha comparando OI tipo I, III e IV. As formas mais graves de OI (tipo III e IV) apresentaram fraturas nos primeiros meses de vida, maior deformidade óssea. Associação inversa entre amplitude de movimento articular geral e o nível da marcha e uma associação direta com idade de início de marcha, o número total de fraturas e a presença de deformidades ósseas. Encontrou-se uma associação direta entre a força muscular geral e o nível da marcha e uma associação inversa com a idade de início de marcha e presença de deformidades ósseas. Conclusão: Estes dados sugerem que as características clínico-funcionais variam de acordo com os tipos de OI. Nas formas moderada e grave de OI há maior limitação funcional influenciada pelo número de fraturas e presença de deformidades ósseas afetando negativamente o nível da marcha. / Osteogenesis Imperfecta (OI) is characterized by bone fragility and susceptibility to fractures. Complications of the disease can affect the physical and motor development, compromising the functional skills, level of gait and independence of the individual. Objective: To evaluate the clinical and functional features of children and adolescents with OI. Methods: A cross-sectional study which evaluated subjects of both genders aged between 0 and 18 years attended in the Reference Center for Treatment of OI of Rio Grande do Sul (CROI-RS). Clinical and functional data were evaluated through specific tokens and functional assessment. We evaluated aspects related to the presence of fractures and bone deformities, gait ability, muscle strength, joint range of motion and use of intramedullary rod. Bone mineral density (BMD) was measured by Dual Energy X-Ray Absoptometry (DEXA). The level of significance was set at 5% (p ≤ 0.05). Results: We found significant differences in the occurrence of fractures, presence of bone deformities, use of intramedullary rod, bone mineral density, drug therapy and aspects related to gait comparing OI types I, III and IV. The age of gait acquisition showed a direct association with overall joint range of motion and an inverse relationship with overall muscle strength. The level of ambulation was directly associated with overall muscle strength and inversely associated with overall joint range of motion. Conclusion: Our findings confirm that clinical and functional features vary according to OI type. Moderate and severe forms of OI are associated with greater functional limitation, influenced by fractures in early life, number of fractures and the presence of bone deformities, which negatively affect the acquisition and level of ambulation.

Abstract Genetic factors and their resulting phenotypes were evaluated in three different bone disorders: osteogenesis imperfecta (OI), juvenile idiopathic osteoporosis (JIO), and stress fractures. The spectrum of the OI phenotypes caused by mutations in the COL1A1 and COL1A2 genes is well defined, but the mechanisms by which the variations affect the hearing phenotype are not well-known. A total of 54 Finnish OI patients with previously diagnosed hearing loss, or aged 35 or more years, were analyzed here for mutations in COL1A1, or COL1A2. Altogether, 49 mutations were identified, of which 41 were novel. No correlation was observed between the mutated gene, or the mutation type, and the hearing pattern. This indicates that the basis of hearing loss in OI is complex, and is a result of multifactorial, still unknown genetic effects, or of variable expressions of the COL1A1 and COL1A2 genes. JIO presents peri-pubertally as an acute symptomatic osteoporosis (bone pain and fractures) in otherwise healthy children, and no underlying cause has yet been identified for this disorder. Here, the analysis of the low-density lipoprotein receptor-related protein 5 gene (LRP5) in 20 patients with JIO revealed two missense mutations (A29T and R1036Q) and one frameshift mutation (C913fs) in 3 of the patients. The LRP5 gene has recently been shown to be also involved in osteoporosis-pseudoglioma syndrome and a high-bone-mass phenotype. Stress fractures are a significant problem among athletes and soldiers. Genetic factors may increase the fracture risk, but no susceptibility genes have yet been identified. Seven genes involved in bone metabolism, or pathology, were studied in terms of their roles in stress fracture. No disease-causing, or predisposing variations were found in the candidate gene, or association analyses, but a highly significant association was found between the phenotype and a vitamin D receptor (VDR) haplotype, TGT, which is composed of three polymorphic sites, FokI, BsmI and TaqI. We showed that femoral neck stress fractures are associated with a certain VDR haplotype, accounting for a five-fold increase in the risk of developing stress fractures, with an associated attributable risk of 12%. The results of this study show that genetic factors play a role in different pathological bone phenotypes. These findings provide new information on the pathogenesis of the disorders and for the development of genetic testing and targeted treatment for the disorders.

Healthy tooth formation is crucially dependent on normal development of enamel and dentin. Any deviation from norm could lead to serious effects on the teeth function. Amelogenesis Imperfecta (AI) and Dentinogenesis Imperfecta (DGI) are genetically inherited conditions that affect the teeth formation. Thus is imperative to investigate the genes and proteins that contribute to these conditions. Some of the known proteins that play a role in amelogenesis include AMELOGENIN (AMLEX), KALLIKREIN 4(KLK4), FAMILY WITH SEQUENCE SIMILARITY 83H (FAM83H), WD REPEAT-CONTAINING PROTEIN 72 (WDR72) and DENTIN SIALOPHSOPHPROTEIN (DSPP). The purpose of this research project was to investigate the expression/localization pattern of gene products which are known to be causative for Amelogenesis Imperfecta and Dentinogenesis Imperfecta.The study was carried out using mouse heads which were fixed, demineralized and paraffin-embedded. Samples were then sectioned and immunohistochemical analysis was performed with various enamel/dentin protein antibodies. The data showed the following results: KLK4 showed immunoreactivity mainly in ameloblasts and in the pulp, DSPP showed immunoreactivity in dentin, in the pulp and in the epithelial cells on one location as indicated by the arrow in figure 3 of the tooth cross section, FAM83H has a faint immunoreactivity identified in the ameloblasts, WDR72 showed weak immunoreactivity in the ameloblasts and AMELX showed immunoreactivity on the enamel and the ameloblasts. In conclusion these findings were supported by previous studies and conveyed the validity of IHC experiments in locating these proteins in odontogenic tissues.