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1.
Am J Hum Genet ; 65(3): 680-8, 1999 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-10441574

RESUMEN

To determine the meiotic instability of the CGG-triplet repeat in the fragile-X gene, FMR1, we examined the size of the repeat in single sperm from four premutation males. The males had CGG-repeat sizes of 68, 75, 78, and 100, as determined in peripheral blood samples. All samples showed a broad range of variations, with expansions more common than contractions. Examination of single lymphocytes indicated that somatic cells were relatively more stable than sperm. Surprisingly, the repeats in sperm from the 75- and 78-repeat males had very different size ranges and distribution patterns despite the similarity of the repeat size and AGG interruption in their somatic cells. These results suggest that cis or trans factors may have a role in male germline repeat instability.


Asunto(s)
Síndrome del Cromosoma X Frágil/genética , Linfocitos/metabolismo , Mutación/genética , Proteínas del Tejido Nervioso/genética , Proteínas de Unión al ARN , Espermatozoides/metabolismo , Expansión de Repetición de Trinucleótido/genética , Adulto , Factores de Edad , Anciano , Femenino , Proteína de la Discapacidad Intelectual del Síndrome del Cromosoma X Frágil , Síndrome del Cromosoma X Frágil/sangre , Mutación de Línea Germinal/genética , Humanos , Masculino , Meiosis/genética , Persona de Mediana Edad , Peso Molecular , Núcleo Familiar
2.
Am J Med Genet ; 83(4): 342-6, 1999 Apr 02.
Artículo en Inglés | MEDLINE | ID: mdl-10208177

RESUMEN

We have been carrying out studies aimed at improving prenatal detection of the fragile X chromosome/mutation. Our current protocol requires a turnaround time (TAT) of several days. In an attempt to reduce the TAT, we have turned to the use of monoclonal antibodies (mAbs). Monoclonal antibody 1A1 (provided by Dr. Mandel of INSERM) immunostaining was performed according to a modified three-step immunocytochemical procedure. We found that cytoplasmic staining intensities, using mAb 1A1/avidin biotinylated complex/diaminobenzidine, varied from light to heavy within each sample, with controls exhibiting a majority of heavily stained cells in both chorionic villus (CV) sample and amniotic fluid cultured cells. Using mAb 1A1 and a new nuclear-specific antibody, mAb 3F11, we found that CV cultured cells harboring the FMR1 full mutation could be distinguished from controls as early as 10 weeks of gestation in both male and female specimens. Western blot analysis showed that the antibodies have similar staining patterns but that mAb 3F11 has fewer background/nonspecific bands. Our results demonstrate that it is feasible to detect fragile X full mutations within one day after obtaining cells from CV specimens taken as early as 10 weeks of gestation.


Asunto(s)
Enfermedades Fetales/genética , Síndrome del Cromosoma X Frágil/genética , Proteínas del Tejido Nervioso/genética , Diagnóstico Prenatal/métodos , Proteínas de Unión al ARN , Secuencia de Aminoácidos , Anticuerpos Monoclonales/inmunología , Núcleo Celular , Citoplasma , Femenino , Enfermedades Fetales/inmunología , Proteína de la Discapacidad Intelectual del Síndrome del Cromosoma X Frágil , Síndrome del Cromosoma X Frágil/inmunología , Humanos , Masculino , Datos de Secuencia Molecular , Mutación , Embarazo
3.
Am J Hum Genet ; 59(6): 1252-61, 1996 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-8940270

RESUMEN

To better define the nature of FMR1 CGG-repeat expansions, changes in allele sizes for 191 families with fragile X and for 33 families with gray-zone repeats (40-60) were analyzed. Expansion of the fragile X chromosome to the full mutation was seen in 13.4% of offspring from premutation mothers with 56-59 repeats, 20.6% of those with 60-69 repeats, 57.8% of those with 70-79 repeats, 72.9% of those with 80-89 repeats, and 97.3% of those with 90-199 repeats. For premutation fathers, the majority (62%) of their daughters had a larger repeat number, while a few had either a smaller (22%) or the same (16%) repeat number, compared with their fathers' sizes. However, daughters with a smaller repeat number were observed only if their fathers had > or = 80 repeats. Fifteen (39.5%) of 38 such daughters carried a smaller repeat than did their fathers. We observed that a similar repeat number was inherited more often than expected by chance, among the members of a sibship segregating fragile X. This familial clustering, observed in the offspring of both males and females with a premutation, implies there may be an additional factor, independent of parental repeat size, that influences CGG-repeat instability. Instability in gray-zone allele transmissions was observed in 25% of alleles with 50-60 CGGs but in <8% of those with 40-49 CGGs. Examination of gray-zone allele organization revealed that long tracts of pure CGGs (>34) are not always unstably transmitted. These results raise new questions regarding the familial factors that may determine transmission expansions.


Asunto(s)
Síndrome del Cromosoma X Frágil/genética , Repeticiones de Trinucleótidos/genética , Alelos , Análisis de Varianza , Fragilidad Cromosómica , Femenino , Humanos , Masculino , Linaje , Reacción en Cadena de la Polimerasa
4.
Am J Med Genet ; 64(2): 287-92, 1996 Aug 09.
Artículo en Inglés | MEDLINE | ID: mdl-8844067

RESUMEN

Three females were identified who have apparent reversal of fragile X premutations. Based on haplotype analysis of nearby markers, they were found to have inherited a fragile X chromosome from their premutation carrier mothers, and yet had normal size FMR1 repeat alleles. The changes in repeat sizes from mother to daughter was 95 to 35 in the first, 145 to 43 in the second, and 82 to 33 in the third. In the first family, mutations of the nearby microsatellites FRAXAC2 and DXS548 were also observed. In the other two, only mutations involving the FMR1 repeats were found. We suggest differing mutational mechanisms such as gene conversion versus DNA replication slippage may underlie such reversions. We estimate that such revertants may occur among 1% or less of premutation carrier offspring. Our results indicate that women identified to be carriers by linkage should be retested by direct DNA analysis.


Asunto(s)
Síndrome del Cromosoma X Frágil/genética , Mutación , Proteínas del Tejido Nervioso/genética , Proteínas de Unión al ARN , Repeticiones de Trinucleótidos , Replicación del ADN , Femenino , Proteína de la Discapacidad Intelectual del Síndrome del Cromosoma X Frágil , Conversión Génica , Tamización de Portadores Genéticos , Ligamiento Genético , Marcadores Genéticos , Haplotipos , Humanos , Masculino , Núcleo Familiar , Linaje
5.
Am J Med Genet ; 51(4): 417-22, 1994 Jul 15.
Artículo en Inglés | MEDLINE | ID: mdl-7943010

RESUMEN

The CGG repeat size distribution of the fragile X mental retardation gene (FMR-1) was studied in a population of normal Chinese X chromosomes along with that of two proximal microsatellite polymorphic markers: FRAXAC1 and DXS548. The most common CGG repeat allele was 29 (47.2%) with 30 being second most common (26%). This distribution was different from that seen in Caucasian controls, where the most common allele was 30 repeats. Other differences with Caucasian controls included a secondary modal peak at 36 repeats and the absence of peaks at 20 or 23 repeats. There were only two FRAXAC1 and five DXS548 alleles found in the Chinese sample. A striking linkage disequilibrium of FMR-1 alleles with FRAXAC1 alleles was observed, in that 90% of the 29 CGG repeat alleles but only 41% of the 30 CGG repeat alleles had the FRAXAC1 152 bp allele (18 AC repeats). This disequilibrium suggests that slippage between the closely spaced normal CGG repeat alleles, 29 and 30, and between 152 and 154 FRAXAC1 alleles is very rare. This study lays the groundwork for an understanding of founder chromosome effects in comparing Asian and Caucasian populations.


Asunto(s)
Síndrome del Cromosoma X Frágil/etnología , Síndrome del Cromosoma X Frágil/genética , Frecuencia de los Genes , Cromosoma X/genética , Alelos , Pueblo Asiatico/genética , China/epidemiología , Fragilidad Cromosómica , ADN Satélite/genética , Efecto Fundador , Síndrome del Cromosoma X Frágil/epidemiología , Genes , Haplotipos , Humanos , Desequilibrio de Ligamiento , Epidemiología Molecular , Secuencias Repetitivas de Ácidos Nucleicos/genética , Población Blanca/genética
6.
Am J Med Genet ; 51(4): 436-42, 1994 Jul 15.
Artículo en Inglés | MEDLINE | ID: mdl-7943013

RESUMEN

Low fragile X frequencies have been commonly observed in chorionic villus sample (CVS) cultures, compared to subsequent analysis in whole blood or products of conception (POC). To investigate possible mechanisms for this effect, CVS cultures from a previously identified fragile X positive male, were restudied and compared to subsequent POC cultures from lung, muscle, skin, and thymus. Cultures were exposed, for the last 24 hours before harvesting, to FUdR, excess thymidine, and a combination of both. For CVS, only those cultures that were exposed to a combination of FUdR and excess thymidine showed positive cytogenetic findings (1/90 or 1.1%), agreeing with our original positive cytogenetic results (2/86 or 2.3%) for cultures exposed to excess thymidine. Fragile X frequencies in the POC tissues from this fetus increased to an average of 14%. PCR analyses showed full mutations (> 200 CGG repeats) in uninduced CVS cultures but induced cultures exhibited apparently smaller sizes in the range of 120-180 repeats. The results showed variability. In one instance, the banding pattern from one of the uninduced cultures was similar to the results where cultures were exposed to a double induction system. When PCR analyses were conducted on induced POC cultures, full mutations were observed in virtually all samples. Southern blot genomic analysis using probe StB12.3 showed an unmethylated full mutation in CVS cultures. Southern blot patterns from cultures of muscle revealed size variations of DNA bands in the premutation range representing unmethylated DNA as well as methylated full mutations. Finally, variations were also observed in lung and skin cultures, compared to CVS and muscle.(ABSTRACT TRUNCATED AT 250 WORDS)


Asunto(s)
Muestra de la Vellosidad Coriónica , Floxuridina/farmacología , Síndrome del Cromosoma X Frágil/diagnóstico , Síndrome del Cromosoma X Frágil/genética , Regulación de la Expresión Génica/efectos de los fármacos , Secuencias Repetitivas de Ácidos Nucleicos/efectos de los fármacos , Southern Blotting , Células Cultivadas/efectos de los fármacos , Vellosidades Coriónicas/efectos de los fármacos , Bandeo Cromosómico , Fragilidad Cromosómica , Técnicas de Cultivo , ADN/metabolismo , Sondas de ADN , Fosfatos de Dinucleósidos/metabolismo , Reacciones Falso Negativas , Femenino , Feto , Frecuencia de los Genes , Humanos , Masculino , Metilación , Mutación , Reacción en Cadena de la Polimerasa , Valor Predictivo de las Pruebas , Embarazo , Timidina/farmacología , Cromosoma X/efectos de los fármacos
7.
Am J Med Genet ; 51(4): 509-12, 1994 Jul 15.
Artículo en Inglés | MEDLINE | ID: mdl-7943031

RESUMEN

Fragile X affected males have an expansion of a CGG repeat and a hypermethylated CpG island 5' to the FMR-1 gene. Mosaic males with both a premutation and full mutation have been noted among the affected individuals. Such mosaic males are most easily identified by the presence of a methylated restriction fragment characteristic of the full mutation and an additional unmethylated fragment in the premutation range in Southern analyses with EcoR I and the methylation-sensitive enzyme Eag I and a probe such as StB12.3. We analyzed a group of affected fragile X males by Southern blotting and found 41% (61/148) to be mosaic. The 148 individuals were divided between 36 pairs of brothers and 76 unrelated males. Little difference in the number of mosaics was seen between the brothers and the unrelated males nor was the expected distribution of mosaicism in brother pairs different from observed. Thus, these data do not suggest a familial basis for mosaicism. Our observation that 41% affected fragile X males were mosaic is significantly higher than previous reports. The difference is likely due to technical modifications which permitted the identification of faint premutation bands in some patients. The high percentage of affected males with mosaicism seen here suggests that the occurrence of such individuals may be a much more frequent event than presently recognized.


Asunto(s)
Síndrome del Cromosoma X Frágil/genética , Mosaicismo , Southern Blotting , ADN/metabolismo , Sondas de ADN , Desoxirribonucleasa EcoRI , Desoxirribonucleasas de Localización Especificada Tipo II , Fosfatos de Dinucleósidos/metabolismo , Salud de la Familia , Dosificación de Gen , Humanos , Masculino , Metilación , Mutación , Reacción en Cadena de la Polimerasa , Secuencias Repetitivas de Ácidos Nucleicos
8.
J Genet Couns ; 3(3): 233-44, 1994 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-24234009

RESUMEN

Molecular analysis of the fragile X (FMR-1) gene identifies female fragile X carriers, but appropriate genetic counseling can only be provided if the limitations of the testing methods are understood. Molecular analysis of this gene is achieved with both the polymerase chain reaction (PCR) and Southern blot techniques. PCR is faster and can determine the actual number of CGG repeats, which modifies genetic counseling substantially. However, for a sizeable percentage of women, PCR alone is not conclusive, and Southern analysis is necessary to complete the study. While this procedure takes longer, it is usually conclusive. Women who present for genetic counseling and carrier testing in the second trimester of pregnancy need this information quickly, and for them the turn-around time is paramount. It is critical that genetic counselors understand these methods so that they can educate their clients and facilitate appropriate follow-up.

9.
JAMA ; 270(13): 1569-75, 1993 Oct 06.
Artículo en Inglés | MEDLINE | ID: mdl-8371467

RESUMEN

OBJECTIVE: To develop a rapid, nonradioactive test using the polymerase chain reaction (PCR) capable of detecting full fragile X mutations, premutations, and resolving normal alleles and to apply this to prenatal diagnosis and carrier screening of pregnant women at risk for fragile X carrier status. DESIGN: Prenatal and blood sample PCR analysis with confirmation by direct Southern blotting and cytogenetic techniques. SETTING: Samples sent to a DNA diagnostic research laboratory at a tertiary referral center. PARTICIPANTS: Pregnant women with a family history of undiagnosed mental retardation or known fragile X syndrome and controls. RESULTS: A rapid, nonradioactive PCR screening protocol for the fragile X mental retardation-1 gene for both normal and mutant alleles was developed. Analysis of 570 control X chromosomes showed a modal number of 30 CGG repeats (range, 12 to 52 repeats) and a calculated heterozygosity of approximately 80%. No excess of homozygosity was found, indicating the test was accurate for normal allele resolution. In addition, 150 unrelated pregnant women were screened. Within known fragile X families, five of 20 pregnant women were diagnosed as carriers. Two new fragile X families were diagnosed among relatives of 130 females with family histories of undiagnosed mental retardation, although no carriers were identified. Prenatal PCR testing of 28 carriers accurately detected nine fetuses with full mutations. CONCLUSIONS: This rapid, nonradioactive PCR protocol allows accurate resolution of normal alleles as well as simultaneous detection of carrier alleles and full mutations. With this approach, efficient screening of pregnant women at risk for fragile X carrier status, subsequent genetic counseling of identified carriers, and reliable prenatal diagnosis can be offered.


Asunto(s)
Síndrome del Cromosoma X Frágil/diagnóstico , Síndrome del Cromosoma X Frágil/genética , Tamización de Portadores Genéticos/métodos , Reacción en Cadena de la Polimerasa/métodos , Diagnóstico Prenatal/métodos , Secuencia de Bases , ADN/aislamiento & purificación , Electroforesis en Gel de Poliacrilamida , Femenino , Humanos , Mediciones Luminiscentes , Datos de Secuencia Molecular , Sondas de Oligonucleótidos , Embarazo , Secuencias Repetitivas de Ácidos Nucleicos
10.
Am J Med Genet ; 46(1): 83-7, 1993 Apr 01.
Artículo en Inglés | MEDLINE | ID: mdl-7684191

RESUMEN

We report on a 3-year-old boy with moderate developmental retardation, microcephaly, and malformations of ears, lids, mouth, and thumbs. Cytogenetic analysis demonstrated a direct duplication of chromosome subregion 4(q21.3-->q31.3). Confirmation of this specific rearrangement was performed by fluorescent in situ hybridization (FISH) with a chromosome painting probe and by means of quantitative Southern hybridization with DNA probes localized within the chromosome 4 region presumed to be duplicated.


Asunto(s)
Anomalías Múltiples/genética , Aberraciones Cromosómicas/genética , Cromosomas Humanos Par 4 , Discapacidades del Desarrollo/genética , Microcefalia/genética , Adulto , Southern Blotting , Preescolar , ADN/análisis , Cara/anomalías , Huesos Faciales/anomalías , Femenino , Humanos , Hibridación Fluorescente in Situ , Cariotipificación , Masculino , Pulgar/anomalías
11.
Clin Genet ; 42(3): 124-8, 1992 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-1395083

RESUMEN

We present a case previously described by Jenkins et al. (1983) as atypical Down syndrome (DS). The initial diagnosis was first made on the basis of phenotypic and cytogenetic data. This analysis was supported by studies of superoxide dismutase (SOD1) activity that maps to band 21q22.1. Results from phenotypic, chromosome banding and SOD1 studies suggested a karyotype of 46,XX,-12,+t(12pter to 12qter::21q21 to 21q22.?2). Using fluorescent in situ hybridization (FISH) for chromosome painting with DNA libraries derived from sorted human chromosomes to stain selectively the chromosomes No. 21 and No. 12, we demonstrate that the marker chromosome 12q+ has no chromosome 21 content but it is derived from chromosome 12.


Asunto(s)
Anomalías Múltiples/genética , Cromosomas Humanos Par 12 , Marcadores Genéticos/genética , Discapacidad Intelectual/genética , Trisomía , Adulto , Femenino , Humanos , Hibridación Fluorescente in Situ
12.
Prog Clin Biol Res ; 317: 269-75, 1989.
Artículo en Inglés | MEDLINE | ID: mdl-2690102

RESUMEN

We have reported recently the sublocalization of an Alzheimer Disease-associated gene that encodes for cerebrovascular beta-amyloid protein (BAP). Its locus appears to be at or proximal to band 21q2105 through band 21q11.1. We have also observed hybridization to chromosome 20 in normal and Down syndrome individuals using the single-stranded form of the probe. Further, we have found that BAP hybridizes to chromosome 9 in lymphoblastoid cells from three individuals from two families with familial Alzheimer Disease (AD). We have now obtained additional data which shows significant hybridization to chromosomes 9,20 and 21 for two normal control individuals, a Down syndrome (DS) individual and three AD individuals. When the normal and Down Syndrome individuals were compared to the group of individuals with AD, significant hybridization to chromosome 9 occurred in the Alzheimer group only (p less than .05). Almost half of the silver grains on chromosome 9 in the three AD individuals were localized to the distal area of the long arm. Whether these observations demonstrate an apparent genetic marker in these three individuals with familial AD, or whether our observations have identified a marker for both familial and sporadic AD will be determined by further studies.


Asunto(s)
Enfermedad de Alzheimer/genética , Amiloide/genética , Cromosomas Humanos Par 9 , Hibridación Genética/genética , Proteínas del Tejido Nervioso/genética , Péptidos beta-Amiloides , Sondas de ADN , Marcadores Genéticos , Humanos
13.
Biochem Biophys Res Commun ; 151(1): 1-8, 1988 Feb 29.
Artículo en Inglés | MEDLINE | ID: mdl-3279948

RESUMEN

We have sublocalized an Alzheimer Disease-associated gene, which encodes for cerebrovascular beta-amyloid protein, to the region from the centromere through the proximal half of band 21q21 using both somatic cell and in situ mapping techniques. In addition we found repeatedly significant but weaker hybridization of the beta-amyloid protein probe to the short arm of chromosome 20. 794 cells were analyzed from whole blood, lymphoblastoid and skin cultures. The latter two types of cultures had parts of the 21st chromosome translocated to other chromosomes facilitating sublocalization.


Asunto(s)
Enfermedad de Alzheimer/genética , Amiloide/genética , Cromosomas Humanos Par 20 , Cromosomas Humanos Par 21 , Genes , Péptidos beta-Amiloides , Línea Celular , Mapeo Cromosómico , ADN/genética , Femenino , Humanos , Masculino , Hibridación de Ácido Nucleico
16.
Biochem Med Metab Biol ; 36(3): 276-82, 1986 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-3801210

RESUMEN

Werner's syndrome and Hutchinson-Gilford progeria syndrome (progeria) are human genetic diseases which may serve as models for the study of premature aging. The basic defects underlying these diseases are unknown. An abnormally high level of urinary hyaluronic acid (HA) excretion has been previously reported in several Werner's and one progeria subject, all from Japan. To determine if a high HA level is a reliable marker for these diseases, we quantitated the urinary excretion of HA in three progeria subjects, one subject with an atypical progeroid syndrome, and a Werner's syndrome subject. Compared to controls, the total urinary HA was found to be markedly increased in the three progeria samples and in the Werner's syndrome sample. These findings support the previous observations indicating elevated HA may be a specific marker for these diseases.


Asunto(s)
Ácido Hialurónico/orina , Progeria/orina , Síndrome de Werner/orina , Adolescente , Adulto , Niño , Preescolar , Femenino , Glicosaminoglicanos/orina , Humanos , Masculino
18.
Neuropediatrics ; 16(2): 98-105, 1985 May.
Artículo en Inglés | MEDLINE | ID: mdl-3925366

RESUMEN

Light microscopic, histochemical and electron-microscopic studies were made on the brain of a case (No. 1) with Sanfilippo disease, type A. In this case pigment preparations of the isocortex have been demonstrated. Ultrastructural investigations of the skin biopsies (his two male siblings) were also studied (cases 2, 3). Our three siblings of MPS III A, have demonstrated ceroid lipofuscin storage in the brain (case No. 1) and skin biopsies (cases No. 2 and 3) in addition to histological features of MPS. The biochemical studies (enzymatic identification) were made in the cultures of fibroblasts. Also, urine quantitative studies for MPS and N-sulfonate to hexosamino ratio were performed.


Asunto(s)
Corteza Cerebral/patología , Mucopolisacaridosis/patología , Mucopolisacaridosis III/patología , Pigmentos Biológicos/metabolismo , Piel/patología , Adulto , Corteza Cerebral/metabolismo , Humanos , Lipofuscina/metabolismo , Microscopía Electrónica , Mucopolisacaridosis III/metabolismo , Lipofuscinosis Ceroideas Neuronales/metabolismo , Lipofuscinosis Ceroideas Neuronales/patología , Linaje
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