Asunto(s)
Factor VIII/genética , Secuencia de Bases , ADN/genética , Análisis Mutacional de ADN , ADN de Cadena Simple/química , ADN de Cadena Simple/genética , Exones , Hemofilia A/sangre , Hemofilia A/genética , Humanos , Datos de Secuencia Molecular , Conformación de Ácido Nucleico , Reacción en Cadena de la Polimerasa , Polimorfismo Genético , Empalme del ARN/genéticaRESUMEN
Leber hereditary optic neuropathy (LHON) is a maternally inherited disorder characterized by bilateral acute or subacute loss of central vision, primarily in young males. A G----A single base mutation at 11778nt of the mitochondrial genome which eliminates a SfaNI restriction site [Wallace et al., 1988; Holt et al., 1989; Hotta et al., 1989; Singh et al., 1989; Vilkki et al., 1989; Yoneda et al., 1989; Stone et al., 1990; Lott et al., 1990.] has been found in more than 60% of the families with LHON studied. We studied 25 persons from 4 families with LHON using SfaNI and Mae III digestion of a 201 base pair polymerase chain reaction (PCR) product encompassing the 11778nt mutation. The loss of the SfaNI site and the acquisition of a Mae III site at 11778nt were identified in all maternal relatives of the LHON families studied. The mutation was heteroplasmic in all affected individuals, female carriers, and males at-risk. The heteroplasmy of mitochondrial DNA (mtDNA) was also identified by direct DNA sequencing of PCR amplified by direct DNA sequencing of PCR amplified mtDNA digested by SfaNI or Mae III. It appears that the proportion of the mutant mtDNA correlates with the severity of the disease.
Asunto(s)
ADN Mitocondrial/genética , Mutación , Atrofias Ópticas Hereditarias/genética , Adenina/química , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Secuencia de Bases , Southern Blotting , Análisis Mutacional de ADN , Femenino , Estudios de Seguimiento , Guanina/química , Humanos , Masculino , Persona de Mediana Edad , Datos de Secuencia Molecular , NADH Deshidrogenasa/genética , Linaje , Reacción en Cadena de la Polimerasa , Polimorfismo de Longitud del Fragmento de RestricciónAsunto(s)
Globinas/genética , Talasemia/genética , Alelos , Pool de Genes , Humanos , México/etnologíaRESUMEN
Single nucleotide substitutions in the promoter regions of the A gamma- and G gamma-globin genes have been associated with increased fetal hemoglobin (HbF) production. We wished to determine whether these or other unrecognized substitutions in the gamma promoter regions are responsible for the 20-fold variation in HbF production in sickle cell patients or normal adults. From a random sampling of 250 sickle cell (SS) patients and 125 normal adults, 17 individuals representing the highest and lowest HbF producers were selected for study. All three common restriction fragment length polymorphism beta-globin region haplotypes (Benin, Central African Republic, and Senegal) were found in both the highest and lowest HbF producers with SS disease. Using the polymerase chain reaction amplification and direct sequencing of the amplified DNA product, we examined the promoter regions of both the A gamma and G gamma genes from -350 bp to +50 bp of the CAP site. No mutations were found in either gamma gene promoter region. We conclude that nucleotide substitutions in the promoter regions (-350 to +50 bp) of both gamma genes are not responsible for the marked variation in HbF production among SS or normal individuals.
Asunto(s)
Anemia de Células Falciformes/genética , Hemoglobina Fetal/genética , Globinas/genética , Regiones Promotoras Genéticas , Adulto , Anemia de Células Falciformes/sangre , Secuencia de Bases , ADN/sangre , ADN/genética , ADN/aislamiento & purificación , Variación Genética , Haplotipos , Humanos , Datos de Secuencia Molecular , Sondas de Oligonucleótidos , Reacción en Cadena de la Polimerasa , Polimorfismo de Longitud del Fragmento de Restricción , Valores de ReferenciaRESUMEN
The origin of nondisjunction in trisomy 21 has so far been studied using cytogenetic heteromorphisms and DNA polymorphisms using Southern blot analysis. Short sequence repeats have recently been described as an abundant class of DNA polymorphisms in the human genome, which can be typed using the polymerase chain reaction (PCR) amplification. We describe the usage of such markers on chromosome 21 in the study of parental origin of the additional chromosome 21 in 87 cases of Down syndrome. The polymorphisms studied were (a) two (GT)n repeats and a poly(A) tract of an Alu sequence within the HMG14 gene and (b) a (GT)n repeat of locus D21S156. The parental origin was determined in 68 cases by studying the segregation of polymorphic alleles in the nuclear families (either by scoring three different alleles in the proband or by dosage comparison of two different alleles in the proband). Our results demonstrate the usefulness of highly informative PCR markers for the study of nondisjunction in Down syndrome.
Asunto(s)
Cromosomas Humanos Par 21 , ADN/genética , Síndrome de Down/genética , Polimorfismo Genético , Secuencias Repetitivas de Ácidos Nucleicos , Alelos , Femenino , Heterocigoto , Humanos , Masculino , Datos de Secuencia Molecular , Reacción en Cadena de la PolimerasaRESUMEN
A (GT)n repeat in intron 4 of the functional human HMG14 gene on chromosome 21 was used as polymorphic marker to map this gene relative to the genetic linkage map of human chromosome 21. Variation in the length of the (GT)n repeat was detected by electrophoresis on polyacrylamide gels of DNA amplified by the polymerase chain reaction using primers flanking the repeat. The observed heterozygosity of this polymorphism in 40 CEPH families was 58% with six different alleles. Linkage analysis localized the HMG14 gene close to the ETS2 gene and locus D21S3 in chromosomal band 21q22.3.
Asunto(s)
Cromosomas Humanos Par 21 , Ligamiento Genético , Proteínas del Grupo de Alta Movilidad/genética , Secuencias Repetitivas de Ácidos Nucleicos , Electroforesis en Gel de Poliacrilamida , Femenino , Genes , Marcadores Genéticos , Humanos , Intrones , Masculino , Linaje , Reacción en Cadena de la Polimerasa , Polimorfismo de Longitud del Fragmento de RestricciónRESUMEN
To identify DNA polymorphisms that are abundant in the human genome and are detectable by polymerase chain reaction amplification of genomic DNA, we tested the hypothesis that the polydeoxyadenylate tract of the Alu family of repetitive elements is polymorphic among human chromosomes. We analyzed the 3' ends of three specific Alu sequences and found that two (in the adenosine deaminase gene and the beta-globin pseudogene) were polymorphic. This novel class of polymorphisms, termed AluVpA [Alu variable poly(A)] may represent one of the most useful and informative group of DNA markers in the human genome.