RESUMO
Facioscapulohumeral muscular dystrophy is an autosomal dominant muscle disorder, mapped to 4q35. It is characterized by remarkable inter- and intrafamilial clinical variability ranging from severe phenotype to asymptomatic carriers. The aim of the present study was to assess the size of the Eco RI fragment in a large sample of asymptomatic or minimally affected carriers as well as symptomatic patients, comparing both sexes, in order to verify if asymptomatic carriers are randomly distributed or concentrated in some particular families and if there is preferential parental transmission (maternal or paternal) resulting in non-penetrant carriers. We have analysed a total of 506 individuals from 106 unrelated families with at least one affected facioscapulohumeral muscular dystrophy proband. In all patients the molecular diagnosis was confirmed following double digestion (Eco RI/Bln I fragment <35 kb). About 20% among probands' relatives who were found to carry the small fragment were asymptomatic or minimally affected, without preferential parental transmission, but with a significantly higher proportion of females (n=37) than males (n=14). Although asymptomatic carriers were found in about 30% of the families, some genealogies seem to concentrate more non-penetrant cases. A significant correlation between the size of the Eco RI fragment and severity of the phenotype was observed in the total sample but surprisingly this correlation is significant only among affected females. The gender difference in clinical manifestation as well as the observation that asymptomatic carriers are not rare should be taken into consideration in genetic counseling of affected patients or 'at-risk' relatives.
Assuntos
Desoxirribonuclease EcoRI/genética , Heterozigoto , Distrofia Muscular Facioescapuloumeral/genética , Adulto , Idoso , Análise Mutacional de DNA , Feminino , Frequência do Gene , Triagem de Portadores Genéticos , Predisposição Genética para Doença/genética , Testes Genéticos , Humanos , Masculino , Pessoa de Meia-Idade , Peso Molecular , Penetrância , Fenótipo , Fatores de Risco , Fatores SexuaisRESUMO
The human immunoglobulin lambda locus ( IGL) is mapped at Chromosome 22q11.2, spanning about 1 Mb of DNA, and directs the synthesis of lambda-type immunoglobulin light chains. The positions of about 73-74 germline V-lambda genes, depending on the haplotypes, are known, with 29-33 of them being functional IGLV genes. These genes were divided into 11 subgroups ( IGLV1 to IGLV11) distributed into three gene clusters ( VA, VB, and VC). We constructed a high-resolution restriction map of a 37-kb cosmid clone (cosmid 8.3) harboring genes of the IGLV1, IGLV7, and IGLV5 families and the non-coding sequences IGLV(I)-42 and IGLV(VII)-41-1, located at cluster VB of the IGL locus. These IGLV genes were associated with unique EcoRI fragments detectable in Southern blots of genomic DNA. Population RFLP has revealed new IGLV alleles and haplotypes. We used the restriction map of cosmid 8.3 and the IMGT database as a reference for RFLP studies. EcoRI Southern blot hybridizations with subgroup-specific probes of the functional and open reading frame sequences present in cosmid 8.3 revealed different frequencies of IGLV gene fragments, as well as deletions of IGLV1-50 and IGLV5-39 genes and RFLP involving IGLV5-45 and IGLV5-48 genes. All members of the IGLV7 subgroup were monomorphic. Sequencing of the genes present in cosmid 8.3 revealed a new allelic variant of the IGLV5 subgroup. These data contribute to a better understanding of the contribution of the germline IGLV genes to the human genetic background and polymorphism.
Assuntos
Cromossomos Humanos Par 22/genética , Cosmídeos , Desoxirribonuclease EcoRI/genética , Região Variável de Imunoglobulina/genética , Cadeias lambda de Imunoglobulina/genética , Polimorfismo Genético , Alelos , Sequência de Aminoácidos , Sequência de Bases , Biomarcadores , Southern Blotting , Elementos de DNA Transponíveis , Deleção de Genes , Frequência do Gene , Genômica , Humanos , Dados de Sequência Molecular , Polimorfismo de Fragmento de RestriçãoRESUMO
Studies that consider polymorphisms within the apolipoprotein B (apo B) gene as risk factors for coronary artery disease (CAD) have reported conflicting results. The aim of the present study was to search for associations between two DNA RFLPs (XbaI and EcoRI) of the apo B gene and CAD diagnosed by angiography. In the present study we compared 116 Brazilian patients (92 men) with CAD (CAD+) to 78 control patients (26 men) without ischemia or arterial damage (CAD-). The allele frequencies at the XbaI (X) and EcoRI (E) sites did not differ between groups. The genotype distributions of CAD+ and CAD- patients were different (chi (1) = 6.27, P = 0.012) when assigned to two classes (X-X-/E+E+ and the remaining XbaI/EcoRI genotypes). Multivariate logistic regression analysis showed that individuals with the X-X-/E+E+ genotype presented a 6.1 higher chance of developing CAD than individuals with the other XbaI/EcoRI genotypes, independently of the other risk factors considered (sex, tobacco consumption, total cholesterol, hypertension, and triglycerides). We conclude that the X-X-/E+E genotype may be in linkage disequilibrium with an unknown variation in the apo B gene or with a variation in another gene that affects the risk of CAD.
Assuntos
Apolipoproteínas B/genética , Doença das Coronárias/genética , Desoxirribonuclease EcoRI/genética , Desoxirribonucleases de Sítio Específico do Tipo II/genética , Polimorfismo Genético/genética , Adulto , Alelos , Estudos de Casos e Controles , Estudos Transversais , Feminino , Marcadores Genéticos , Genótipo , Humanos , Masculino , Pessoa de Meia-Idade , Análise Multivariada , Polimorfismo de Fragmento de Restrição , Estudos Prospectivos , Fatores de RiscoRESUMO
A genetically structured mathematical model was developed and used to evaluate the influence of molecular parameters involved in the expression of a harmful recombinant protein (SPA::EcoRI). The system consists of the controlled expression of the endonuclease EcoRI cloned in the plasmid pMTC48. The control is exerted by the lambda CI repressor expressed from the plasmid pRK248cIts. The deleterious effect of the activity of the enzyme EcoRI on the host DNA is prevented by the action of the EcoRI methylase that is expressed constitutively from a third plasmid, pEcoR4. The model includes molecular mechanisms involved in the regulation of the expression of these genes and is used to determine cultural conditions that maximize the production of the recombinant protein.
Assuntos
Proteínas de Ligação a DNA , Escherichia coli/genética , Regulação Bacteriana da Expressão Gênica/genética , Modelos Genéticos , Plasmídeos/genética , Proteína Estafilocócica A/biossíntese , Simulação por Computador , Dano ao DNA , Desoxirribonuclease EcoRI/biossíntese , Desoxirribonuclease EcoRI/genética , Escherichia coli/classificação , Escherichia coli/metabolismo , Engenharia Genética/métodos , Cinética , Modelos Biológicos , Modelos Químicos , Biossíntese de Proteínas , Proteínas Recombinantes de Fusão/biossíntese , Proteínas Recombinantes de Fusão/genética , Proteínas Repressoras/genética , Proteínas Repressoras/metabolismo , Reprodutibilidade dos Testes , Sensibilidade e Especificidade , Especificidade da Espécie , Proteína Estafilocócica A/genética , Staphylococcus/genética , Transcrição Gênica , Proteínas Virais , Proteínas Virais Reguladoras e AcessóriasRESUMO
The human immunoglobulin lambda variable 8 (IGLV8) subgroup is a gene family containing three members, one of them included in a monomorphic 3.7-kb EcoRI genomic fragment located at the major lambda variable locus on chromosome 22q11.1 (gene IGLV8a, EMBL accession No. Z73650) at 100% frequency in the normal urban population. The second is a polymorphic RFLP allele included in a 6.0-kb EcoRI fragment at 10% frequency, and the third is located in a monomorphic 8.0-kb EcoRI fragment at 100% frequency, the last being translocated to chromosome 8q11.2 and considered to be an orphan gene. Our Southern blot-EcoRI-RFLP studies in normal individuals and in patients with rheumatoid arthritis (RA) or with systemic lupus erythematosus (SLE), using a specific probe for the IGLV8 gene family (probe pVL8, EMBL accession No. X75424), have revealed the two monomorphic genomic fragments containing the IGLV8 genes, i.e., the 3.7-kb fragment from chromosome 22q11.1 and the 8.0-kb fragment from 8q11.2, both occurring at 100% frequency (103 normal individuals, 48 RA and 28 SLE patients analyzed), but absence of the 6.0-kb IGLV8 polymorphic RFLP allele in all RA or SLE patients. As expected, the frequency of the 6.0-kb allele among the normal individuals was 10%. These findings suggest an association between the absence of the 6.0-kb EcoRI fragment and rheumatoid arthritis and systemic lupus erythematosus.
Assuntos
Artrite Reumatoide/genética , Desoxirribonuclease EcoRI/genética , Cadeias lambda de Imunoglobulina/genética , Lúpus Eritematoso Sistêmico/genética , Polimorfismo de Fragmento de Restrição , Alelos , Southern Blotting , Cromossomos Humanos Par 22/genética , Cromossomos Humanos Par 8/genética , Feminino , Humanos , MasculinoRESUMO
The human immunoglobulin lambda variable 8 (IGLV8) subgroup is a gene family containing three members, one of them included in a monomorphic 3.7-kb EcoRI genomic fragment located at the major lambda variable locus on chromosome 22q11.1 (gene IGLV8a, EMBL accession No. Z73650) at 100 percent frequency in the normal urban population. The second is a polymorphic RFLP allele included in a 6.0-kb EcoRI fragment at 10 percent frequency, and the third is located in a monomorphic 8.0-kb EcoRI fragment at 100 percent frequency, the last being translocated to chromosome 8q11.2 and considered to be an orphan gene. Our Southern blot-EcoRI-RFLP studies in normal individuals and in patients with rheumatoid arthritis (RA) or with systemic lupus erythematosus (SLE), using a specific probe for the IGLV8 gene family (probe pVL8, EMBL accession No. X75424), have revealed the two monomorphic genomic fragments containing the IGLV8 genes, i.e., the 3.7-kb fragment from chromosome 22q11.1 and the 8.0-kb fragment from 8q11.2, both occurring at 100 percent frequency (103 normal individuals, 48 RA and 28 SLE patients analyzed), but absence of the 6.0-kb IGLV8 polymorphic RFLP allele in all RA or SLE patients. As expected, the frequency of the 6.0-kb allele among the normal individuals was 10 percent. These findings suggest an association between the absence of the 6.0-kb EcoRI fragment and rheumatoid arthritis and systemic lupus erythematosus
Assuntos
Humanos , Masculino , Feminino , Artrite Reumatoide/genética , Desoxirribonuclease EcoRI/genética , Cadeias lambda de Imunoglobulina/genética , Lúpus Eritematoso Sistêmico/genética , Polimorfismo de Fragmento de Restrição , Alelos , Southern Blotting , Cromossomos Humanos Par 22/genética , Cromossomos Humanos Par 8/genéticaRESUMO
The nucleotide (nt) sequence of a 2.7-kb HindIII-EcoRI DNA fragment encoding the bstVIR and bstVIM genes has been determined. The sequence predicts a restriction endonuclease of 224 amino acids (aa), M(r) 25,104, and a methyl-transferase of 561 aa, M(r0 65,702. Both genes are aligned in the same orientation and are separated by a 102-nt intergenic region. No homology was found between R.BstVI and M.BstVI when their deduced aa sequences were compared. Significant similarity at the aa level was found, however, when both enzymes were compared to their equivalents in the paeR7IRM system of Pseudomonas aeruginosa PAO303.