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M.A. / Dwarfism is a medical condition of disproportionate short stature and occurs in about one in every 25 000 children born worldwide (Scott, 1996). There are more than 200 types of dwarfism (Wikipedia, 2006), of which the most common form of dwarfism is Achondroplasia occurring in about 80% of all dwarfs (Little People’s Research Fund, 2006). Dwarfism is plagued by negative stereotyping and stigmatisation. There is a paucity of existing research on dwarfism, and in particular it’s associated psychological aspects. Existing literature is largely focused on parents’ reactions towards their dwarf child but it is possible that the negative attention dwarfs receive when in public can directly affect a dwarf’s close relationships, in particular, those with their siblings. Therefore, the aim of the present study was to explore the experiences of non-dwarf siblings growing up with a dwarf sibling. A sibling relationship is an emotional bond or transaction existing between two brothers, two sisters or between a brother and a sister. This relationship can have both positive and negative aspects (Bank & Kahn, 1982) and these can be more profound with the presence of a sibling with a disability (Ferrari & Sussman, 1987). Previous studies of sibling relationships with a disability have found various negative aspects, for example, feelings of isolation, resentment, anger and guilt, as well as an increase of stress in the family (Carpenter, 1997). However, research also suggested positive aspects, including an acceptance of diversity and an appreciation for life and psychological growth (Connors & Stalker, 2003). Therefore, it was thought to be possible that these negative and positive aspects may also hold true for a sibling relationship in which one member is a dwarf.

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.

Deleterious gene interactions due to accumulation of individual genetic variations between different lineages are a cause of population diversification by creating reproductive barriers that ultimately lead to differentiation of species. One type of deleterious interactions is called “hybrid necrosis”, in which epistatic interactions between some plant immunity genes (usually very variable) cause autoimmunities that produce a necrotic and dwarf phenotype. Hybrid necrosis has been widely studied in several plant species, such as Arabidopsis thaliana and many gene interactions were found for that plant. This study tests the applicability of these results on a close relative, A. lyrata, by crossing individuals from different populations and genotyping F2 progeny with polymorphic markers close to homologous sequences to those involved in hybrid necrosis in A. thaliana. Results suggest the possibility of a homologous gene to DM8 or DM9 in chromosome 7 to be involved in formation of hybrid necrosis.

Die menschliche Entwicklung ist charakterisiert durch ein rasches fetales Wachstum, ein langsames postnatales Wachstum, ein kontinuierliches Wachstum im Laufe der Kindheit sowie einen Wachstumsschub während der Pubertät. In den letzten Jahren wurde gezeigt, dass Mutationen in den Genen des Pericentrins (PCNT) und des Insulin-like growth factor-1 Rezeptors (Insulin ähnlicher Wachstumsfaktor Typ 1 Rezeptor, IGF1R) seltene Auslöser von prä- und postnataler Wachstumsrestriktion darstellen können. In dieser Arbeit wird eine stark wachstumsretardierte Patientin mit zusammengesetzter heterozygoter PCNT-Mutation und heterozygoter IGF1R-Mutation beschrieben. Ziel dieser Arbeit war zum einen die ausführliche klinische Charakterisierung der Patientin. Zum anderen sollte auf zellulärer Ebene überprüft werden, inwieweit die genannten Mutationen den Phänotyp der Patientin erklären. Um die funktionellen Zusammenhänge zu untersuchen, wurden in vitro Assays durchgeführt. Hierfür standen neben mit dem mutierten Rezeptor transfizierte IGF1R-defiziente Mausfibroblasten (R--Zellen) auch humane Fibroblasten zur Verfügung. Es wurden die totale und die extrazelluläre Rezeptorexpression, die IGF1 induzierte Stimulierung und die Signaltransduktion des mutierten IGF1R untersucht. Weiterhin wurde die proliferative Kapazität der Patientenfibroblasten analysiert. Die Ergebnisse dieser Analysen ergaben keine relevanten Funktionseinschränkungen des mutierten IGF1R. Demgegenüber steht eine reduzierte Zellproliferation der Patientenfibroblasten. Die zugrunde liegenden Mechanismen der verminderten Proliferationskapazität sind womöglich den PCNT-Mutationen zuzurechnen. In Versuchen zur IGF1 induzierten Proliferationssteigerung konnte die Proliferation der Patientenfibroblasten zwar kurzfristig stimuliert werden, bei längerer IGF1-Stimulation konnte jedoch das bestehende Proliferationsdefizit nicht ausgeglichen werden. Die genauen molekularbiologischen Auswirkungen der PCNT-Mutation in Bezug auf den ausgeprägten Phänotyp der Patientin müssen in zukünftigen Arbeiten noch weiter aufgeklärt werden.

Body mass varies considerably between different mammals and this variation is largely accounted for by a difference in total cell number rather than individual cell size. Insights into mechanisms regulating growth can therefore be gained by understanding what governs total cell number at any one point. In addition, control of cell proliferation and programmed cell death is fundamental to other areas of research such as cancer and stem cell research. Microcephalic Primordial Dwarfism (MPD) is a group of rare Mendelian human disorders in which there is an extreme global failure of growth with affected individuals often only reaching a height of around one metre in adulthood. To date, all identified disease genes follow an autosomal recessive mode of inheritance and encode key regulators of the cell cycle, where mutations impact on overall cell number and result in a substantially reduced body size. MPD therefore provides a valuable model for examining genetic and cellular mechanisms that impact on growth. The overall aims of this thesis were to identify novel disease causing genes, as well as provide further characterisation of known disease causing genes, through the analysis of whole exome sequencing (WES) within a large cohort of MPD patients. Following the design and implementation of an analytical bioinformatics pipeline, deleterious mutations were identified in multiple disease genes including LIG4 and XRCC4. Both genes encode components of the non-homologous end joining machinery, a DNA repair mechanism not previously implicated in MPD. Additionally, the pathogenicity of novel mutations in subunits of a protein complex involved in chromosome segregation was assessed using patient-derived cells. These findings demonstrate WES can be successfully implemented to identify known and novel disease causing genes within a large heterogeneous cohort of patients, expanding the phenotype of known disorders and improving diagnosis as well as providing novel insights into intrinsic cellular mechanisms critical to growth.

Não existe relato da condição periodontal em indivíduos com Deficiência Isolada do Hormônio do Crescimento (IGHD). O objetivo deste estudo foi investigar possíveis associações entre IGHD e a perda clínica de inserção periodontal (PCI) em uma população com IGHD congênita, presente no Nordeste do Brasil. Material e Métodos: Todos os indivíduos previamente identificados com IGHD e com idade 12 anos foram elegíveis para participar do estudo (n=46). A amostra final ficou composta por 33 casos (IGHD) e 33 controles (não - IGHD) após a exclusão dos edêntulos (n=5) e dos que haviam recebido previamente tratamento com reposição do Hormônio do Crescimento (n=8). Eles foram pareados por idade, gênero, condição sócio-econômica, hábito de fumo e diabetes. Todos foram submetidos a exame periodontal completo em 6 sítios por dente, e entrevistados por meio de um questionário estruturado. Resultados: Indivíduos com IGHD apresentaram quantidade semelhante de biofilme (p=0,32), menos cálculo supragengival (p=0,01), e mais sangramento à sondagem (p<0,01) em comparação com os controles. Após uma série de análises de regressão logística múltipla condicional, ajustada para cálculo supragengival, indivíduos com IGHD mostraram maior chance de apresentar Perda Clínica de Inserção Periodontal 7mm (OR= 18,1; IC 95% = 2,4 - 137,2). Conclusão: Indivíduos com IGHD severa e congênita possuem maior chance de apresentar Perda Clínica de Inserção Periodontal. / There are no reports of periodontal status in subjects with Isolated Growth Hormone Deficiency (IGHD). The aim of this study was to investigate possible associations between IGHD and periodontal clinical attachment loss (CAL) in a population affected by congenital IGHD, residing in Northeastern Brazil. Material and Methods: All previously identified IGHD subjects age 12 years were eligible for this study (n=46). The final study sample comprised 33 cases (IGHD) and 33 controls (non - IGHD) after excluding edentulous (n = 5) and subjects previously treated with GH replacement (n = 8). They were matched by age, gender, socioeconomic status, smoking and diabetes status. Subjects were submitted to a full-mouth clinical examination of six sites per tooth and were interviewed using a structured, written questionnaire. Results: IGHD subjects had same amount visible plaque (p=0.32), less supragingival calculus (p = 0.01), and more bleeding on probing (p < 0.01) than controls. After performance of conditional multiple regression analyses adjusted by supragingival calculus, IGHD subjects had a higher likelihood of having CAL 7 mm (OR = 18.1; 95% Cl = 2.4 - 137.2). Conclusion: Severe congenital IGHD subjects have a greater chance of having Periodontal Clinical Attachment Loss.

Não existe relato da condição periodontal em indivíduos com Deficiência Isolada do Hormônio do Crescimento (IGHD). O objetivo deste estudo foi investigar possíveis associações entre IGHD e a perda clínica de inserção periodontal (PCI) em uma população com IGHD congênita, presente no Nordeste do Brasil. Material e Métodos: Todos os indivíduos previamente identificados com IGHD e com idade 12 anos foram elegíveis para participar do estudo (n=46). A amostra final ficou composta por 33 casos (IGHD) e 33 controles (não - IGHD) após a exclusão dos edêntulos (n=5) e dos que haviam recebido previamente tratamento com reposição do Hormônio do Crescimento (n=8). Eles foram pareados por idade, gênero, condição sócio-econômica, hábito de fumo e diabetes. Todos foram submetidos a exame periodontal completo em 6 sítios por dente, e entrevistados por meio de um questionário estruturado. Resultados: Indivíduos com IGHD apresentaram quantidade semelhante de biofilme (p=0,32), menos cálculo supragengival (p=0,01), e mais sangramento à sondagem (p<0,01) em comparação com os controles. Após uma série de análises de regressão logística múltipla condicional, ajustada para cálculo supragengival, indivíduos com IGHD mostraram maior chance de apresentar Perda Clínica de Inserção Periodontal 7mm (OR= 18,1; IC 95% = 2,4 - 137,2). Conclusão: Indivíduos com IGHD severa e congênita possuem maior chance de apresentar Perda Clínica de Inserção Periodontal. / There are no reports of periodontal status in subjects with Isolated Growth Hormone Deficiency (IGHD). The aim of this study was to investigate possible associations between IGHD and periodontal clinical attachment loss (CAL) in a population affected by congenital IGHD, residing in Northeastern Brazil. Material and Methods: All previously identified IGHD subjects age 12 years were eligible for this study (n=46). The final study sample comprised 33 cases (IGHD) and 33 controls (non - IGHD) after excluding edentulous (n = 5) and subjects previously treated with GH replacement (n = 8). They were matched by age, gender, socioeconomic status, smoking and diabetes status. Subjects were submitted to a full-mouth clinical examination of six sites per tooth and were interviewed using a structured, written questionnaire. Results: IGHD subjects had same amount visible plaque (p=0.32), less supragingival calculus (p = 0.01), and more bleeding on probing (p < 0.01) than controls. After performance of conditional multiple regression analyses adjusted by supragingival calculus, IGHD subjects had a higher likelihood of having CAL 7 mm (OR = 18.1; 95% Cl = 2.4 - 137.2). Conclusion: Severe congenital IGHD subjects have a greater chance of having Periodontal Clinical Attachment Loss.

Indivíduos com Deficiência Isolada do Hormônio do Crescimento (IGHD), homozigotos para a mutação c.57+1G>A no gene do receptor do hormônio liberador do hormônio de crescimento (GHRH), apresentam maior chance de apresentarem perda de inserção periodontal devido a possível efeito direto da IGHD sobre os tecidos periodontais e/ou a repercussões locais ou sistêmicas da IGHD sobre a resposta imune. Este estudo teve como objetivos avaliar as repercussões locais e sistêmicas da IGHD sobre a resposta imune e comparar os níveis dos patógenos periodontais. Material e Métodos: Foi composto por uma amostra de 19 indivíduos com IGHD e 19 indivíduos no grupo controle, pareados por idade, gênero, condição sócio-econômica, tabagismo e diabetes. Todos foram submetidos a exame periodontal completo, em 6 sítios por dente, e entrevistados por meio de um questionário estruturado. Foi realizada coleta de biofilme subgengival (em sítios rasos e profundos, pareados pela PCS) para verificar os níveis dos microorganismos. Além disso, foram realizadas coletas do fluido gengival (dos mesmos sítios) e do sangue, de ambos os grupos, com a finalidade de analisar o perfil das citocinas inflamatórias. Resultados: Indivíduos com IGHD apresentaram maior quantidade de MMP-8 e CRP (p=0,026 e 0,002) no fluido gengival coletado dos sítios profundos, maior quantidade de IL-17 (p=0,02) no soro e mesmos níveis dos patógenos periodontais, em comparação com os controles (p>0,05). Conclusões: Mesmo com um perfil microbiológico semelhante, indivíduos com a IGHD apresentam alterações imunológicas moderadas (aumento de Interleucina 17 no soro e de metaloproteinase-8 e Proteína C-Reativa no fluido gengival coletado de sítios profundos), comparados aos controles. / Isolated Growth Hormone Deficiency (IGHD) subjects, homozygous to a mutation c.57+1G>A in the growth hormone releasing hormone receptor (GHRHR) gene, have a greater chance of having periodontal attachment loss (PAL) due to a possible direct effect of IGHD on the periodontal tissues and/or locals and systemic effects of IGHD on immune response. This aims of this study was evaluate local and systemic effects of IGHD on immune response and compare periodontal pathogens levels. Material and Methods: The sample was composed of 19 IGHD individuals and 19 controls, matched by age, gender, socio-economic condition, smoking and diabetes. Participants were submitted to a clinical full-mouth periodontal examination of six sites per tooth and were interviewed using a structured questionnaire. Subgingival biofilm was collected (in shallow and deep sites matched by probing clinical depth) to check the periodontal pathogens levels. Futhermore, gingival crevicular fluid (same sites) and blood samples were also collected from both groups to analyze inflammatory cytokines profile. Results: IGHD subjects had significantly higher amounts of MMP-8 and CRP (p= 0.026 e 0.002) in the gingival crevicular fluid collected from deep sites, higher amounts of IL-17 (p=0.02) in serum, and same levels of periodontal pathogens, compairing to the control group (p>0.05). Conclusions: Despite the same microorganism profile, IGHD subjects had moderate immunological alterations (increased serum Interleukin 17 and metalloproteinase 8 and C - reactive protein in deep sites gingival fluid), comparing to controls.

Indivíduos com Deficiência Isolada do Hormônio do Crescimento (IGHD), homozigotos para a mutação c.57+1G>A no gene do receptor do hormônio liberador do hormônio de crescimento (GHRH), apresentam maior chance de apresentarem perda de inserção periodontal devido a possível efeito direto da IGHD sobre os tecidos periodontais e/ou a repercussões locais ou sistêmicas da IGHD sobre a resposta imune. Este estudo teve como objetivos avaliar as repercussões locais e sistêmicas da IGHD sobre a resposta imune e comparar os níveis dos patógenos periodontais. Material e Métodos: Foi composto por uma amostra de 19 indivíduos com IGHD e 19 indivíduos no grupo controle, pareados por idade, gênero, condição sócio-econômica, tabagismo e diabetes. Todos foram submetidos a exame periodontal completo, em 6 sítios por dente, e entrevistados por meio de um questionário estruturado. Foi realizada coleta de biofilme subgengival (em sítios rasos e profundos, pareados pela PCS) para verificar os níveis dos microorganismos. Além disso, foram realizadas coletas do fluido gengival (dos mesmos sítios) e do sangue, de ambos os grupos, com a finalidade de analisar o perfil das citocinas inflamatórias. Resultados: Indivíduos com IGHD apresentaram maior quantidade de MMP-8 e CRP (p=0,026 e 0,002) no fluido gengival coletado dos sítios profundos, maior quantidade de IL-17 (p=0,02) no soro e mesmos níveis dos patógenos periodontais, em comparação com os controles (p>0,05). Conclusões: Mesmo com um perfil microbiológico semelhante, indivíduos com a IGHD apresentam alterações imunológicas moderadas (aumento de Interleucina 17 no soro e de metaloproteinase-8 e Proteína C-Reativa no fluido gengival coletado de sítios profundos), comparados aos controles. / Isolated Growth Hormone Deficiency (IGHD) subjects, homozygous to a mutation c.57+1G>A in the growth hormone releasing hormone receptor (GHRHR) gene, have a greater chance of having periodontal attachment loss (PAL) due to a possible direct effect of IGHD on the periodontal tissues and/or locals and systemic effects of IGHD on immune response. This aims of this study was evaluate local and systemic effects of IGHD on immune response and compare periodontal pathogens levels. Material and Methods: The sample was composed of 19 IGHD individuals and 19 controls, matched by age, gender, socio-economic condition, smoking and diabetes. Participants were submitted to a clinical full-mouth periodontal examination of six sites per tooth and were interviewed using a structured questionnaire. Subgingival biofilm was collected (in shallow and deep sites matched by probing clinical depth) to check the periodontal pathogens levels. Futhermore, gingival crevicular fluid (same sites) and blood samples were also collected from both groups to analyze inflammatory cytokines profile. Results: IGHD subjects had significantly higher amounts of MMP-8 and CRP (p= 0.026 e 0.002) in the gingival crevicular fluid collected from deep sites, higher amounts of IL-17 (p=0.02) in serum, and same levels of periodontal pathogens, compairing to the control group (p>0.05). Conclusions: Despite the same microorganism profile, IGHD subjects had moderate immunological alterations (increased serum Interleukin 17 and metalloproteinase 8 and C - reactive protein in deep sites gingival fluid), comparing to controls.