Assuntos
Actinas/metabolismo , Junções Célula-Matriz/metabolismo , Mecanotransdução Celular , Músculo Liso/metabolismo , Actinas/deficiência , Animais , Aorta/metabolismo , Colágeno/metabolismo , Matriz Extracelular/metabolismo , Imageamento Tridimensional , Camundongos Endogâmicos C57BL , Microscopia de Fluorescência , Relaxamento MuscularRESUMO
Thoracic aortic aneurysms are life-threatening lesions that afflict young and old individuals alike. They frequently associate with genetic mutations and are characterized by reduced elastic fibre integrity, dysfunctional smooth muscle cells, improperly remodelled collagen and pooled mucoid material. There is a pressing need to understand better the compromised structural integrity of the aorta that results from these genetic mutations and renders the wall vulnerable to dilatation, dissection or rupture. In this paper, we compare the biaxial mechanical properties of the ascending aorta from 10 murine models: wild-type controls, acute elastase-treated, and eight models with genetic mutations affecting extracellular matrix proteins, transmembrane receptors, cytoskeletal proteins, or intracellular signalling molecules. Collectively, our data for these diverse mouse models suggest that reduced mechanical functionality, as indicated by a decreased elastic energy storage capability or reduced distensibility, does not predispose to aneurysms. Rather, despite normal or lower than normal circumferential and axial wall stresses, it appears that intramural cells in the ascending aorta of mice prone to aneurysms are unable to maintain or restore the intrinsic circumferential material stiffness, which may render the wall biomechanically vulnerable to continued dilatation and possible rupture. This finding is consistent with an underlying dysfunctional mechanosensing or mechanoregulation of the extracellular matrix, which normally endows the wall with both appropriate compliance and sufficient strength.
Assuntos
Aorta , Aneurisma da Aorta Torácica , Modelos Animais de Doenças , Proteínas da Matriz Extracelular , Modelos Cardiovasculares , Mutação , Animais , Aorta/metabolismo , Aorta/patologia , Aorta/fisiopatologia , Aneurisma da Aorta Torácica/genética , Aneurisma da Aorta Torácica/metabolismo , Aneurisma da Aorta Torácica/patologia , Aneurisma da Aorta Torácica/fisiopatologia , Proteínas da Matriz Extracelular/genética , Proteínas da Matriz Extracelular/metabolismo , CamundongosRESUMO
Moyamoya disease (MMD) is a progressive vasculopathy characterized by occlusion of the terminal portion of the internal carotid arteries and its branches, and the formation of compensatory moyamoya collateral vessels. Homozygous mutations in GUCY1A3 have been reported as a cause of MMD and achalasia. Probands (n = 96) from unrelated families underwent sequencing of GUCY1A3. Functional studies were performed to confirm the pathogenicity of identified GUCY1A3 variants. Two affected individuals from the unrelated families were found to have compound heterozygous mutations in GUCY1A3. MM041 was diagnosed with achalasia at 4 years of age, hypertension and MMD at 18 years of age. MM149 was diagnosed with MMD and hypertension at the age of 20 months. Both individuals carry one allele that is predicted to lead to haploinsufficiency and a second allele that is predicted to produce a mutated protein. Biochemical studies of one of these alleles, GUCY1A3 Cys517Tyr, showed that the mutant protein (a subunit of soluble guanylate cyclase) has a significantly blunted signaling response with exposure to nitric oxide (NO). GUCY1A3 missense and haploinsufficiency mutations disrupt NO signaling leading to MMD and hypertension, with or without achalasia.
Assuntos
Acalasia Esofágica/genética , Hipertensão/genética , Doença de Moyamoya/genética , Mutação , Óxido Nítrico/metabolismo , Transdução de Sinais/genética , Guanilil Ciclase Solúvel/genética , Adolescente , Adulto , Animais , Criança , Pré-Escolar , Estudos de Coortes , Feminino , Humanos , Lactente , Masculino , Pessoa de Meia-Idade , Dinâmica não Linear , Análise de Regressão , Células Sf9 , Guanilil Ciclase Solúvel/químicaRESUMO
Marfan syndrome (MFS) due to mutations in FBN1 is a known cause of thoracic aortic aneurysms and acute aortic dissections (TAAD) associated with pleiotropic manifestations. Genetic predisposition to TAAD can also be inherited in families in the absence of syndromic features, termed familial TAAD (FTAAD), and several causative genes have been identified to date. FBN1 mutations can also be identified in FTAAD families, but the frequency of these mutations has not been established. We performed exome sequencing of 183 FTAAD families and identified pathogenic FBN1 variants in five (2.7%) of these families. We also identified eight additional FBN1 rare variants that could not be unequivocally classified as disease-causing in six families. FBN1 sequencing should be considered in individuals with FTAAD even without significant systemic features of MFS.
Assuntos
Aneurisma da Aorta Torácica/genética , Dissecção Aórtica/genética , Fibrilina-1/genética , Predisposição Genética para Doença/genética , Mutação , Adulto , Idoso , Dissecção Aórtica/patologia , Aneurisma da Aorta Torácica/patologia , Exoma/genética , Saúde da Família , Feminino , Humanos , Masculino , Síndrome de Marfan/genética , Síndrome de Marfan/patologia , Pessoa de Meia-Idade , Linhagem , Análise de Sequência de DNA/métodosRESUMO
Mutations in ACTA2 (smooth muscle cell-specific isoform of α-actin) lead to a predisposition to thoracic aortic aneurysms and other vascular diseases. More recently, the ACTA2 R179H mutation has been described in individuals with global smooth muscle dysfunction. We report a patient heterozygous for the mutation in ACTA2 R179H who presented with megacystis at 13 weeks gestational age and, at birth, with prune-belly sequence. He also had deep skin dimples and creases on his palms and soles, a finding not previously described but possibly related to ACTA2. To our knowledge, this is the first report of the R179H mutation in ACTA2 in a child with prune-belly sequence. We think the R179H mutation in ACTA2 should be included in the differential diagnosis of individuals presenting with the sequence without an identified mechanical obstruction. Furthermore, as ACTA2 R179H has been reported in patients with severe vasculomyopathy and premature death, we recommend that molecular testing for this mutation be considered in fetuses presenting with fetal megacystis with a normal karyotype, particularly if the bladder diameter is 15 mm or more, to allow expectant parents to make an informed decision.
Assuntos
Actinas/genética , Mutação , Síndrome do Abdome em Ameixa Seca/genética , Dermatopatias/genética , Humanos , Recém-Nascido , Masculino , Fenótipo , Síndrome do Abdome em Ameixa Seca/patologia , Ultrassonografia Pré-NatalRESUMO
BACKGROUND: Mutations in the transforming growth factor beta receptor type I and II genes (TGFBR1 and TGFBR2) cause Loeys-Dietz syndrome (LDS), characterised by thoracic aortic aneurysms and dissections (TAAD), aneurysms and dissections of other arteries, craniosynostosis, cleft palate/bifid uvula, hypertelorism, congenital heart defects, arterial tortuosity, and mental retardation. TGFBR2 mutations can also cause TAAD in the absence of features of LDS in large multigenerational families, yet only sporadic LDS cases or parent-child pairs with TGFBR1 mutations have been reported to date. METHODS: The authors identified TGFBR1 missense mutations in multigenerational families with TAAD by DNA sequencing. Clinical features of affected individuals were assessed and compared with clinical features of previously described TGFBR2 families. RESULTS: Statistical analyses of the clinical features of the TGFBR1 cohort (n = 30) were compared with clinical features of TGFBR2 cohort (n = 77). Significant differences were identified in clinical presentation and survival based on gender in TGFBR1 families but not in TGFBR2 families. In families with TGFBR1 mutations, men died younger than women based on Kaplan-Meier survival curves. In addition, men presented with TAAD and women often presented with dissections and aneurysms of arteries other than the ascending thoracic aorta. The data also suggest that individuals with TGFBR2 mutations are more likely to dissect at aortic diameters <5.0 cm than individuals with TGFBR1 mutations. CONCLUSION: This study is the first to demonstrate clinical differences between patients with TGFBR1 and TGFBR2 mutations. These differences are important for the clinical management and outcome of vascular diseases in these patients.
Assuntos
Aneurisma da Aorta Torácica/genética , Dissecção Aórtica/genética , Mutação de Sentido Incorreto , Proteínas Serina-Treonina Quinases/genética , Receptores de Fatores de Crescimento Transformadores beta/genética , Adolescente , Adulto , Distribuição de Qui-Quadrado , Estudos de Coortes , Saúde da Família , Feminino , Predisposição Genética para Doença , Humanos , Estimativa de Kaplan-Meier , Angiografia por Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Linhagem , Receptor do Fator de Crescimento Transformador beta Tipo I , Receptor do Fator de Crescimento Transformador beta Tipo IIRESUMO
Marfan syndrome (MFS), a relatively common autosomal dominant hereditary disorder of connective tissue with prominent manifestations in the skeletal, ocular, and cardiovascular systems, is caused by mutations in the gene for fibrillin-1 (FBN1). The leading cause of premature death in untreated individuals with MFS is acute aortic dissection, which often follows a period of progressive dilatation of the ascending aorta. Recent research on the molecular physiology of fibrillin and the pathophysiology of MFS and related disorders has changed our understanding of this disorder by demonstrating changes in growth factor signalling and in matrix-cell interactions. The purpose of this review is to provide a comprehensive overview of recent advances in the molecular biology of fibrillin and fibrillin-rich microfibrils. Mutations in FBN1 and other genes found in MFS and related disorders will be discussed, and novel concepts concerning the complex and multiple mechanisms of the pathogenesis of MFS will be explained.
Assuntos
Síndrome de Marfan/genética , Receptores de Ativinas Tipo I/genética , Dissecção Aórtica/genética , Animais , Aneurisma da Aorta Torácica/genética , Proteínas Contráteis/fisiologia , Bases de Dados Genéticas , Proteínas da Matriz Extracelular/fisiologia , Fibrilina-1 , Fibrilinas , Humanos , Proteínas de Ligação a TGF-beta Latente/genética , Síndrome de Marfan/complicações , Camundongos , Microfibrilas/metabolismo , Proteínas dos Microfilamentos/genética , Modelos Animais , Modelos Biológicos , Desnaturação Proteica/genética , Proteínas Serina-Treonina Quinases , Fatores de Processamento de RNA , Receptor do Fator de Crescimento Transformador beta Tipo I , Receptor do Fator de Crescimento Transformador beta Tipo II , Receptores de Fatores de Crescimento Transformadores beta/genéticaAssuntos
Anodontia/diagnóstico , Anodontia/genética , Adolescente , Adulto , Criança , Feminino , Humanos , Masculino , Linhagem , VietnãRESUMO
The pathogenesis of systemic sclerosis (SSc) involves complex interactions between activated fibroblasts eventually leading to fibrosis, and impaired immune tolerance characterized by a variety of circulating SSc-specific autoantibodies. The expression of autoantigens in fibroblasts, a key target tissue in SSc, may play an important role in this process. To obtain a global view of this process, we examined gene expression profiles of SSc dermal fibroblasts using cDNA microarrays. The results show that dermal fibroblasts from SSc patients obtained from either affected or unaffected skin displayed a characteristic pattern of increased SSc autoantigen gene expression compared with that from normal controls. In particular, fibrillarin (p = 0.028), centromeric protein B (p = 0.01), centromeric autoantigen P27 (p = 0.042), and RNA polymerase II (220 kDa; p = 0.02) were significantly overexpressed in SSc fibroblasts. Quantitative RT-PCR confirmed overexpression of these autoantigens and also revealed increased levels of DNA topoisomerase I transcripts in SSc fibroblasts compared with normal control fibroblasts (p = 0.0318). The polymyositis/scleroderma autoantigen gene was overexpressed in some SSc patients (p = 0.09). To examine the specificity of these overexpressed autoantigen genes for SSc and its tissue specificity for fibroblasts, cDNA microarrays of dermal fibroblasts from patients with eosinophilic fasciitis and scleromyxedema were studied as well as PBMC and muscle biopsies from SSc patients. None of these tissues showed significant alterations in gene expression of SSc-specific autoantigens. Therefore, SSc-associated autoantigen genes are selectively overexpressed in SSc dermal fibroblasts, a major tissue involved in disease pathogenesis.
Assuntos
Autoantígenos/genética , Autoantígenos/metabolismo , Derme/citologia , Fibroblastos/metabolismo , Escleroderma Sistêmico/genética , Escleroderma Sistêmico/imunologia , Doenças Autoimunes/genética , Doenças Autoimunes/imunologia , Células Cultivadas , Perfilação da Expressão Gênica , Humanos , Análise de Sequência com Séries de Oligonucleotídeos , RNA Mensageiro/biossíntese , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Ativação TranscricionalRESUMO
OBJECTIVE: To determine if there are abnormalities in fibrillin 1-containing microfibrils in the extracellular matrix (ECM) of primary dermal fibroblasts explanted from patients with systemic sclerosis (SSc). METHODS: Explanted fibroblasts from unaffected skin of 12 SSc patients were used to examine fibrillin 1-containing microfibrils by immunofluorescence (IF) using a monoclonal antibody (mAb) to fibrillin 1. Metabolic labeling of the fibroblast cultures was used to study the synthesis, secretion, and processing of fibrillin 1, as well as to observe microfibril formation and stability. Microfibrils elaborated by the SSc cells were analyzed by electron microscopy for ultrastructural abnormalities, and the results were confirmed by immunoblotting. RESULTS: Control and SSc fibroblasts displayed a prominent meshwork of fibrillin 1-containing microfibrils when visualized by IF using a fibrillin 1 mAb. Paradoxically, metabolic studies indicated a paucity of fibrillin 1 in the ECM in the majority of the SSc fibroblast strains. Subsequent rotary-shadowed electron microscopy revealed reduced amounts of and ultrastructural abnormalities in the microfibrils elaborated by all strains of SSc cells. Immunoblots confirmed the lack of the high molecular weight form of fibrillin 1 in the SSc fibroblasts of Choctaw American Indians. Finally, in vitro studies indicated that the amount of fibrillin 1 in the ECM of SSc cells diminished at a faster rate than the amount of fibrillin 1 in the ECM of control cells with time. CONCLUSION: Although SSc fibroblasts assemble microfibrils, these microfibrils are unstable, suggesting that an inherent defect of fibrillin 1-containing microfibrils may play a role in the pathogenesis of SSc.
Assuntos
Derme/citologia , Fibroblastos/ultraestrutura , Microfibrilas/ultraestrutura , Proteínas dos Microfilamentos/metabolismo , Escleroderma Sistêmico/patologia , Adulto , Idoso , Anticorpos Monoclonais/imunologia , Células Cultivadas , Proteínas da Matriz Extracelular/imunologia , Proteínas da Matriz Extracelular/metabolismo , Feminino , Fibrilina-1 , Fibrilinas , Fibroblastos/metabolismo , Imunofluorescência , Humanos , Cinética , Masculino , Microfibrilas/metabolismo , Proteínas dos Microfilamentos/imunologia , Pessoa de Meia-Idade , Escleroderma Sistêmico/etiologia , Escleroderma Sistêmico/metabolismoRESUMO
Mutations in FBN1 cause the autosomal dominant condition, Marfan syndrome. A single-base mutation that results in a skipping of exon 2 of FBN1 was found in a Marfan patient. By sequencing this proband's entire FBN1 gene and comparing the mutated DNA sequence with proband's unaffected family numbers, we confirmed this alteration was the causative mutation. The skipping of exon 2 creates a frameshift and premature termination codon, and forms a truncated fibrillin-1 composed only of 55 amino acids of N-terminus plus 45 nonsense amino acids. The mRNA transcription levels of the mutated FBN1 allele and the deposition of fibrillin-1 into extracellular matrix in fibroblast cells culture were assessed.
Assuntos
Processamento Alternativo/genética , Éxons , Síndrome de Marfan/genética , Proteínas dos Microfilamentos/genética , Adulto , Sequência de Bases , DNA/química , DNA/genética , Análise Mutacional de DNA , Saúde da Família , Feminino , Fibrilina-1 , Fibrilinas , Mutação da Fase de Leitura , Humanos , Masculino , Síndrome de Marfan/patologia , Mutação , LinhagemRESUMO
BACKGROUND: Aortic aneurysms cause significant mortality, and >20% relate to hereditary disorders. Familial aortic aneurysm (FAA) has been described in such conditions as the Marfan and Ehlers-Danlos type IV syndromes, due to defects in the fibrillin-1 and type III procollagen genes, respectively. Other gene defects that cause isolated aneurysms, however, have not thus far been described. METHODS AND RESULTS: We studied 3 families affected by FAA. No family met the diagnostic criteria for either Marfan or Ehlers-Danlos syndrome. Echocardiography defined involvement of both the thoracic and abdominal aorta. In family ANA, candidate gene analysis excluded linkage to loci associated with aneurysm formation, including fibrillin-1, fibrillin-2, and type III procollagen, and chromosome 3p24.2-p25. Genome-wide linkage analysis identified a 2.3-cM FAA locus (FAA1) on chromosome 11q23.3-q24 with a maximum multipoint logarithm of the odds score of 4.4. In family ANB, FAA was linked to fibrillin-1. In family ANF, however, FAA was not linked to any locus previously associated with aneurysm formation, including fibrillin-1 and FAA1. CONCLUSIONS: FAA disease is genetically heterogeneous. We have identified a novel FAA locus at chromosome 11q23.3-q24, a critical step toward elucidating 1 gene defect responsible for aortic dilatation. Future characterization of the FAA1 gene will enhance our ability to achieve presymptomatic diagnosis of aortic aneurysms and will define molecular mechanisms to target therapeutics.
Assuntos
Aneurisma Aórtico/genética , Cromossomos Humanos Par 11/genética , Adolescente , Adulto , Idoso , Aneurisma Aórtico/patologia , Criança , Pré-Escolar , Bandeamento Cromossômico , Mapeamento Cromossômico , Saúde da Família , Feminino , Heterogeneidade Genética , Predisposição Genética para Doença/genética , Humanos , Lactente , Escore Lod , Masculino , Repetições de Microssatélites , Pessoa de Meia-Idade , LinhagemRESUMO
BACKGROUND: Aneurysms and dissections affecting the ascending aorta are associated primarily with degeneration of the aortic media, called medial necrosis. Families identified with dominant inheritance of thoracic aortic aneurysms and dissections (TAA/dissections) indicate that single gene mutations can cause medial necrosis in the absence of an associated syndrome. METHODS AND RESULTS: Fifteen families were identified with multiple members with TAAs/dissections. DNA from affected members from 2 of the families was used for a genome-wide search for the location of the defective gene by use of random polymorphic markers. The data were analyzed by the affected-pedigree-member method of linkage analysis. This analysis revealed 3 chromosomal loci with multiple markers demonstrating evidence of linkage to the phenotype. Linkage analysis using further markers in these regions and DNA from 15 families confirmed linkage of some of the families to 5q13-14. Genetic heterogeneity for the condition was confirmed by a heterogeneity test. Data from 9 families with the highest conditional probability of being linked to 5q were used to calculate the pairwise and multipoint logarithm of the odds (LOD) scores, with a maximum LOD of 4.74, with no recombination being obtained for the marker D5S2029. In 6 families, the phenotype was not linked to the 5q locus. CONCLUSIONS: A major locus for familial TAAs and dissections maps to 5q13-14, with the majority (9 of 15) of the families identified demonstrating evidence of linkage to this locus. The condition is genetically heterogeneous, with 6 families not demonstrating evidence of linkage to any loci previously associated with aneurysm formation.
Assuntos
Aneurisma da Aorta Torácica/genética , Dissecção Aórtica/genética , Proteínas da Matriz Extracelular , Proteoglicanas , Dissecção Aórtica/patologia , Aneurisma da Aorta Torácica/patologia , Proteoglicanas de Sulfatos de Condroitina/genética , Mapeamento Cromossômico , Cromossomos Humanos Par 5/genética , Saúde da Família , Feminino , Heterogeneidade Genética , Genoma Humano , Genótipo , Haplótipos , Humanos , Lectinas Tipo C , Escore Lod , Masculino , Repetições de Microssatélites , Linhagem , Polimorfismo de Nucleotídeo Único , Proteínas/genética , Análise de Sequência de DNA , Trombospondinas/genética , VersicanasRESUMO
Smith-Lemli-Opitz syndrome (SLOS) is a hereditary disorder in which a defective gene encoding 7-dehydrocholesterol reductase causes the accumulation of noncholesterol sterols, such as 7- and 8-dehydrocholesterol. Using rigorous analytical methods in conjunction with a large collection of authentic standards, we unequivocally identified numerous noncholesterol sterols in 6 normal and 17 SLOS blood samples. Plasma or erythrocytes were saponified under oxygen-free conditions, followed by multiple chromatographic separations. Individual sterols were identified and quantitated by high performance liquid chromatography (HPLC), Ag(+)-HPLC, gas chromatography (GC), GC-mass spectrometry, and nuclear magnetic resonance. As a percentage of total sterol content, the major C(27) sterols observed in the SLOS blood samples were cholesterol (12;-98%), 7-dehydrocholesterol (0.4;-44%), 8-dehydrocholesterol (0.5;-22%), and cholesta-5,7,9(11)-trien-3beta-ol (0.02;-5%), whereas the normal blood samples contained <0.03% each of the three noncholesterol sterols. SLOS and normal blood contained similar amounts of lathosterol (0.05;-0.6%) and cholestanol (0.1;-0.4%) and approximately 0.003;-0.1% each of the Delta(8), Delta(8(14)), Delta(5,8(14)), Delta(5,24), Delta(6,8), Delta(6,8(14)), and Delta(7,24) sterols. The results are consistent with the hypothesis that the Delta(8(14)) sterol is an intermediate of cholesterol synthesis and indicate the existence of undescribed aberrant pathways that may explain the formation of the Delta(5,7,9(11)) sterol. 19-Norcholesta-5,7,9-trien-3beta-ol was absent in both SLOS and normal blood, although it was routinely observed as a GC artifact in fractions containing 8-dehydrocholesterol. The overall findings advance the understanding of SLOS and provide a methodological model for studying other metabolic disorders of cholesterol synthesis.
Assuntos
Oxirredutases atuantes sobre Doadores de Grupo CH-CH , Síndrome de Smith-Lemli-Opitz/sangue , Esteróis/sangue , Adulto , Colesterol na Dieta/administração & dosagem , Cromatografia Líquida de Alta Pressão , Feminino , Humanos , Lactente , Espectroscopia de Ressonância Magnética , Masculino , Estrutura Molecular , Oxirredutases/genética , Esteróis/química , Esteróis/isolamento & purificaçãoRESUMO
OBJECTIVE: Previously, we demonstrated with the use of microsatellite markers that a 2-cM haplotype on chromosome 15q containing the fibrillin 1 gene (FBN1) was strongly associated with systemic sclerosis (SSc) in the Choctaw, a population with high SSc prevalence. In this study, all 69 known FBN1 exons were sequenced to ascertain the presence of changes that might show associations with SSc in the Choctaw and Japanese SSc patients and controls. METHODS: Screening of FBN1 exons was accomplished by polymerase chain reaction-based fluorescence sequencing of genomic DNA using single-nucleotide polymorphism (SNP) haplotypes, and their frequencies were determined with a new algorithm that recognizes past recombination events between sites. Haplotype phylogenies were inferred using the median-joining network analysis. RESULTS: Five SNPs were identified in FBN1. They are located in the 5'-untranslated region (SNP-1), exon 15 (SNP-2), intron 17 (SNP-3), exon 27 (SNP-4), and intron 27 (SNP-5). Only SNP-1 (T-->C) demonstrated an association with SSc in the Choctaw. Eleven FBN1 SNP haplotypes were ascertained in the Choctaw population, 2 of which (SNPs 5 and 6) were found only in the SSc patients. These same FBN1 SNP haplotypes were associated with SSc in the Japanese. CONCLUSION: A SNP in the 5'-untranslated region of FBN1 (SNP-1, C allele) was strongly associated with SSc in the Choctaw. Furthermore, this polymorphism is present on 2 unique FBN1 haplotypes found only in Choctaw SSc patients. The same 2 haplotypes demonstrate associations with SSc in the Japanese. These data extend the earlier microsatellite studies and are consistent with the hypothesis that FBN1 or a nearby gene on chromosome 15q is involved in SSc susceptibility in the Choctaw and the Japanese.
Assuntos
Povo Asiático , Indígenas Norte-Americanos , Proteínas dos Microfilamentos/genética , Polimorfismo de Nucleotídeo Único , Escleroderma Sistêmico/genética , Regiões 5' não Traduzidas , DNA/análise , Primers do DNA/química , Éxons/genética , Feminino , Fibrilina-1 , Fibrilinas , Frequência do Gene , Haplótipos , Humanos , Japão/epidemiologia , Masculino , Dados de Sequência Molecular , Reação em Cadeia da Polimerase , Polimorfismo Conformacional de Fita Simples , Escleroderma Sistêmico/etnologia , Análise de Sequência de DNA , Estados Unidos/epidemiologiaRESUMO
A large east Texas family with autosomal dominant inheritance of a novel bleeding disorder has been identified. The disorder is characterized clinically by easy bruising, life-threatening bleeding with trauma or surgery, and menorrhagia in affected women. Laboratory studies demonstrated prolongation of the prothrombin time and activated partial thromboplastin time in affected individuals. Paradoxically, assays of known coagulation factors are all within normal limits. To determine the molecular basis of this disease, a candidate gene linkage analysis in this kindred was done. Initially it was hypothesized that the cause of the disease in this family could be an antithrombin III (AT3) mutation that resulted in a constitutively active AT3 in the absence of heparin binding. Linkage studies using DNA from the family and an intragenic polymorphic marker within the AT3 gene showed that the disease mapped to this locus. The coding region and intron/exon junctions of AT3 were sequenced using the proband's DNA, but this analysis failed to identify a mutation. Additional family members were recruited for the study, and 16 polymorphic markers around the AT3 gene were analyzed. Using 2 recombinants, the critical interval for the defective gene was narrowed to approximately 1.5 Mb, centromeric to AT3. The factor V (FV) gene was mapped into the disease interval and sequenced; there were no mutations found. Elucidation of the genetic defect causing the bleeding disorder in this family may reveal a novel protein involved in the coagulation cascade.
Assuntos
Genes Dominantes/genética , Hemorragia/genética , Adulto , Antitrombina III/genética , Fatores de Coagulação Sanguínea , Testes de Coagulação Sanguínea , Mapeamento Cromossômico/métodos , Cromossomos Humanos Par 1/genética , Fator V/genética , Saúde da Família , Feminino , Ligação Genética , Marcadores Genéticos , Haplótipos , Hemorragia/epidemiologia , Hemorragia/etiologia , Humanos , Masculino , Mutação , Linhagem , Texas/epidemiologiaRESUMO
Over the last decade, a considerable amount of new information has emerged describing the protein components of elastic fibers. It is now evident that elastic fibers are complex extracellular matrix polymers, composed of at least 19 different proteins that comprise both the microfibrillar and the amorphous components of elastic fibers. Mutations in three of the genes encoding the most abundant of these elastic fiber proteins result in a broad spectrum of elastic tissue phenotypes, ranging from skeletal and skin abnormalities to vascular and ocular defects. The following disorders will be discussed in this review: supravalvular aortic stenosis; Williams-Beuren syndrome; cutis laxa; Marfan syndrome; ectopia lentis; familial thoracic aortic aneurysms and dissections; MASS syndrome; isolated skeletal features of Marfan syndrome; Shprintzen-Goldberg syndrome; and congenital contractural arachnodactyly.