RESUMO
The role of human chromosome 2 in type 1 diabetes was evaluated by analysing linkage and linkage disequilibrium at 21 microsatellite marker loci, using 348 affected sibpair families and 107 simplex families. The microsatellite D2S152 was linked to, and associated with, disease in families from three different populations. Our evidence localizes a new diabetes susceptibility gene, IDDM7, to within two centiMorgans of D2S152. This places it in a region of chromosome 2q that shows conserved synteny with the region of mouse chromosome 1 containing the murine type 1 diabetes gene, Idd5. These results demonstrate the utility of polymorphic microsatellites for linkage disequilibrium mapping of genes for complex diseases.
Assuntos
Mapeamento Cromossômico , Cromossomos Humanos Par 2 , Diabetes Mellitus Tipo 1/genética , Desequilíbrio de Ligação , Adolescente , Adulto , Alelos , Animais , Sequência de Bases , Primers do DNA/genética , DNA Satélite/genética , Feminino , Marcadores Genéticos , Humanos , Masculino , Camundongos , Dados de Sequência MolecularRESUMO
Partial exclusion mapping of the nonobese (NOD) diabetic mouse genome has shown linkage of diabetes to at least five different chromosomes. We have now excluded almost all of the genome for the presence of susceptibility genes with fully recessive effects and have obtained evidence of linkage of ten distinct loci to diabetes or the prediabetic lesion, insulitis, indicative of a polygenic mode of inheritance. The relative importance of these loci and their interactions have been assessed using a new application of multiple polychotomous regression methods. A candidate disease gene, interleukin-2 (Il-2), which is closely linked to insulitis and diabetes, is shown to have a different sequence in NOD, including an insertion and a deletion of tandem repeat sequences which encode amino acid repeats in the mature protein.
Assuntos
Doenças Autoimunes/genética , Mapeamento Cromossômico , Diabetes Mellitus Tipo 1/genética , Diabetes Mellitus Tipo 1/imunologia , Interleucina-2/genética , Camundongos Endogâmicos NOD/genética , Sequência de Aminoácidos , Animais , Sequência de Bases , Cruzamentos Genéticos , DNA Complementar/genética , Feminino , Ligação Genética , Marcadores Genéticos , Masculino , Camundongos , Camundongos Endogâmicos C57BL/genética , Camundongos Endogâmicos NOD/imunologia , Dados de Sequência Molecular , Oligodesoxirribonucleotídeos , Pancreatopatias/genética , Pancreatopatias/imunologia , Análise de RegressãoRESUMO
Type 1 or insulin-dependent diabetes mellitus (IDDM) is an autoimmune disease of the insulin-producing pancreatic beta-cells which is determined by both genetic and environmental factors. The major histocompatibility complex and the insulin gene region (INS) on human chromosomes 6p and 11p, respectively, contain susceptibility genes. Using a mostly French data set, evidence for linkage of INS to IDDM was recently obtained but only in male meioses (suggesting involvement of maternal imprinting) and only in HLA-DR4-positive diabetics. In contrast, we find evidence for linkage in both male and female meioses and that the effect of the susceptibility gene(s) in the INS region is not dependent on the presence of HLA-DR4.
Assuntos
Diabetes Mellitus Tipo 1/genética , Ligação Genética/genética , Antígeno HLA-DR4/genética , Insulina/genética , Sequência de Bases , Linhagem Celular , Diabetes Mellitus Tipo 1/etnologia , Suscetibilidade a Doenças , Feminino , Antígeno HLA-DR4/análise , Haplótipos/genética , Humanos , Linfócitos/imunologia , Masculino , Meiose/genética , Dados de Sequência Molecular , Noruega , Pais , Fatores de Risco , Reino UnidoRESUMO
Microsatellites are tandem repeats of simple sequence that occur abundantly and at random throughout most eukaryotic genomes. Since they are usually less than 100 bp long and are embedded in DNA with unique sequence, they can be amplified in vitro using the polymerase chain reaction. Microsatellites are easy to clone and characterize and display considerable polymorphism due to variation in the number of repeat units. This polymorphism is sufficiently stable to use in genetic analyses. Microsatellites are therefore ideal markers for constructing high-resolution genetic maps in order to identify susceptibility loci involved in common genetic diseases.
Assuntos
DNA Satélite/genética , Ligação Genética , Animais , Sequência de Bases , DNA , Humanos , Dados de Sequência Molecular , Reação em Cadeia da PolimeraseRESUMO
Forty-three sequences containing simple sequence repeats or microsatellites were generated from an M13 library of total genomic mouse DNA. These sequences were analyzed for size variation using the polymerase chain reaction and gel electrophoresis without the need for radiolabeling. Seventy-two percent of the sequences showed allelic size variations between different inbred strains of mouse and the wild mouse, Mus spretus; and 53% showed variation between inbred strains. Thirty-seven percent were variant between B6/J and DBA/2J, and 81% of these were resolved using minigel agarose electrophoresis alone. This approach is a useful way of generating the large number of variants that are needed to create high resolution maps of the mouse genome.
Assuntos
Mapeamento Cromossômico , DNA Satélite/genética , Variação Genética , Camundongos Endogâmicos/genética , Muridae/genética , Animais , Sequência de Bases , Biblioteca Gênica , Camundongos , Dados de Sequência Molecular , Oligodesoxirribonucleotídeos , Reação em Cadeia da Polimerase/métodos , Sequências Repetitivas de Ácido NucleicoRESUMO
Two genes, Idd-3 and Idd-4, that influence the onset of autoimmune type 1 diabetes in the nonobese diabetic mouse have been located on chromosomes 3 and 11, outside the chromosome 17 major histocompatibility complex. A genetic map of the mouse genome, analysed using the polymerase chain reaction, has been assembled specifically for the study. On the basis of comparative maps of the mouse and human genomes, the homologue of Idd-3 may reside on human chromosomes 1 or 4 and Idd-4 on chromosome 17.
Assuntos
Doenças Autoimunes/genética , Diabetes Mellitus Experimental/genética , Diabetes Mellitus Tipo 1/genética , Animais , Mapeamento Cromossômico , Genes , Ligação Genética , Ilhotas Pancreáticas/patologia , Camundongos , Camundongos Mutantes , Pancreatite/genética , Pancreatite/patologia , Polimorfismo de Fragmento de Restrição , Sequências Repetitivas de Ácido NucleicoRESUMO
Microsatellite sequences, such as dinucleotide repeats, show a high degree of polymorphism in eukaryotic DNA. These sequences are convenient as genetic markers and can be analyzed by the polymerase chain reaction (PCR). We have assessed the frequency of length variants in 18 mononucleotide repeats in mouse DNA and find that the variability is similar to that reported for dinucleotide repeats. Nine of the 18 repeat sequences (50%) have three or more alleles in the strains tested. Ten of these repeat sequences have been mapped using strain distribution patterns (SDPs) in recombinant inbred (RI) strains.
Assuntos
Sequências Repetitivas de Ácido Nucleico , Animais , Sequência de Bases , Mapeamento Cromossômico , DNA Satélite , Camundongos , Dados de Sequência Molecular , Reação em Cadeia da PolimeraseRESUMO
Mouse sequence information from the EMBL and GenBank databases, published sequences and genomic clones have been analyzed for simple repetitive elements or microsatellites. Each microsatellite has been amplified by the polymerase chain reaction (PCR) as a single locus marker. PCR primers were designed from unique sequence flanking each repeat. Size variation of PCR products less than 750 base pairs (bp) between mouse strains has been determined using ethidium bromide-stained acrylamide or agarose gels. A further 74 newly characterized microsatellites are presented in this paper, bringing to 185 the total we have analyzed. Of these, 157/185 (85%) have more than one allele, 143/178 (80%) vary in length between C57BL/6J and Mus spretus, and 82/168 (49%) vary between DBA/2J and C57BL/6J. Microsatellites provide informative single locus probes for linkage analysis in the construction of a genetic map of the mouse genome.