Mutations in genes of importance for cartilage development may lead to skeletal malformations, chondroskeletal dysfunction and increased susceptibility to degenerative joint disease. Characterization of these mutations and identification of molecular pathways for the corresponding gene products have contributed to our understanding of mechanisms regulating skeletal patterning, endochondral ossification and joint formation. A five generation family segregating autosomal dominant osteochondritis dissecans (OCD) was identified. Affected family members presented with OCD in knees, hips and elbows, short stature, and early osteoarthritis. A genome wide scan and a multipoint linkage analysis identified aggrecan (ACAN) as a prime candidate gene. DNA sequence analysis of the ACAN-gene revealed heterozygosity for a missense mutation (c.6907G>A) in affected subjects, resulting in a p.V2303M substitution in the aggrecan G3 domain C-type lectin. This domain is important for the interaction with other proteins in the cartilage extracellular matrix. To determine the effect of the V2303M substitution on secretion and interaction, we performed binding studies with recombinant mutated and wild type G3 proteins. We found decreased affinity or complete loss of interaction between V2303M aggrecan and fibulin1, fibulin2 and tenascin-R. Analysis of articular cartilage from an affected family member confirmed that V2303M aggrecan is produced and present. In search for gene mutations associated with multiple epiphyseal dysplasia (MED) we considered the ACAN-gene a likely candidate. The ACAN-gene was analysed in 39 individuals with MED and screened negative for mutations in six previously known MED genes. Sequence analysis revealed a heterozygous missense mutation (c.1448G>T) in one adult male and compound heterozygous missense mutations (c.1366T>C and c.836G>A) in a five year old boy with healthy parents, each of them carrier for one of the mutations. A large family segregating autosomal dominant brachymesophalangia and OCD in finger joints was characterised. The clinical presentation in six affected family members was consistent with the diagnosis Brachydactyly type A1, in this family characterized by shortening of the middle phalanges, short ulnar styloid process, flattening of the metacarpal heads and mild osteoarthritis. The condition may be caused by mutations in the Indian hedgehog gene (IHH) or a yet unidentified gene on chromosome 5p13. Sequence analysis of the IHH-gene in affected individuals revealed a novel C to T transition (c.472C>T) leading to a p.158Arg>Cys substitution. Residue 158 in IHH is highly conserved throughout evolution and molecular structure modelling of IHH suggests that the R158C substitution leads to a conformational change at the site of interaction with the IHH-receptor. This supports that the substitution causes Brachydactyly type A1 in this family. In summary, we report on the clinical, radiological and molecular genetic characteristics of the three skeletal disorders OCD, MED and BDA1. Our results provide a novel molecular mechanism in the pathophysiology of familial osteochondritis dissecans confirming the importance of aggrecan C-type lectin for cartilage function. We also show that ACAN-gene mutations may be associated with MED extending the spectrum of skeletal dysplasias associated with the aggrecan gene. Finally, we report on a novel missense mutation in a conserved region of the IHH-gene associated with BDA1.

Made available in DSpace on 2015-05-08T14:53:37Z (GMT). No. of bitstreams: 1 arquivototal.pdf: 958288 bytes, checksum: 96e8f893e65870e14e2f18b157219114 (MD5) Previous issue date: 2013-12-30 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / The objective of this study is to analyze the influence of risk factors on exposure to WMSD workers in repetitive activities in the footwear sector. Therefore, we analyzed the data for 71 workplaces in the productive area of a shoe company which are characterized by having a defined task cycle, and had the index of exposure to WMSD upper limbs calculated through the OCRA method. Data analysis was accomplished using the exploratory data analysis of WMSD and construction of a Generalized Linear Model (GLM). This model identified the factors that influence the rate of exposure the most and made it possible to quantify the possible chance of raising this index when risk factors are present in the workplaces. The factor indicated as the most influential one was the "sudden movements" factor, the presence of this factor increases the chance of raising the level of exposure in 2.12 times more than when this factor is not present. / O objetivo deste trabalho foi analisar os fatores de risco e o índice de exposição a LER/DORT dos trabalhadores em atividades repetitivas no setor calçadista.Para tanto foram analisados dados referentes a 71 postos de trabalho da área produtiva de uma empresa calçadista que se caracterizam por possuir um ciclo de tarefa definido, e que tiveram calculados o índice de exposição a LER/DORT nos membros superiores através do método OCRA. O tratamento dos dados foi realizado através da análise exploratória dos dados de LER/DORT e da construção de um Modelo Linear Generalizado (MLG).Este modeloidentificou os fatores que mais influenciam o índice de exposição e possibilitouquantificar a chance de elevação deste índice quando os fatores de risco estão presentes nos postos de trabalho. O fator indicado como o mais influente foi o fator movimentos bruscos , a presença deste fator aumenta a chance de se elevar o índice de exposição em 2,12 vezes a mais do que quando este fator não está presente.

No description available.