RESUMEN
OBJECTIVE: The frequency of subtelomeric rearrangements in patients with unexplained mental retardation (MR) is uncertain, as most studies have been retrospective and case retrieval may have been biased towards cases more likely to have a chromosome anomaly. To ascertain the frequency of cytogenetic anomalies, including subtelomeric rearrangements, we prospectively screened a consecutive cohort of cases with unexplained MR in an academic tertiary centre. METHODS: Inclusion criteria were: age <18 years at referral, IQ<85, no aetiological diagnosis after complete examination, which included karyotyping with high resolution banding (HRB). RESULTS: In 266 karyotyped children, anomalies were detected in 20 (7.5%, seven numerical, 13 structural); 39 cases were analysed by FISH for specific interstitial microdeletions, and anomalies were found in nine (23%). FISH analyses for subtelomeric microdeletions were performed in 184 children (44% moderate-profound MR, 51% familial MR), and one rearrangement (0.5%) was identified in a non-familial MR female with mild MR (de novo deletion 12q24.33-qter). The number of probable polymorphisms was considerable: 2qter (n=7), Xpter (n=3), and Ypter (n=1). A significantly higher total number of malformations and minor anomalies was present in the cytogenetic anomaly group compared to the group without cytogenetic anomalies. CONCLUSIONS: The total frequency of cytogenetic anomalies in this prospective study was high (1:10), but the frequency of subtelomeric rearrangements was low. The most likely explanations are the high quality of HRB cytogenetic studies and the lack of clinical selection bias. Conventional cytogenetic analyses, combined with targeted microdeletion testing, remain the single most effective way of additional investigation in mentally retarded children, also in a tertiary centre.
Asunto(s)
Aberraciones Cromosómicas , Pruebas Genéticas/métodos , Discapacidad Intelectual/etiología , Discapacidad Intelectual/genética , Telómero/genética , Adolescente , Niño , Preescolar , Bandeo Cromosómico , Cromosomas Artificiales Bacterianos/genética , Cromosomas Artificiales de Bacteriófagos P1/genética , Estudios de Cohortes , Femenino , Humanos , Lactante , Masculino , Metafase/genética , Países Bajos , Hibridación de Ácido Nucleico , Estudios Prospectivos , Secuencias Repetidas en Tándem/genéticaAsunto(s)
Trastorno Autístico/complicaciones , Trastorno Autístico/genética , Discapacidad Intelectual/complicaciones , Discapacidad Intelectual/genética , Adolescente , Adulto , Trastorno Autístico/diagnóstico , Trastorno Autístico/etiología , Electroencefalografía , Femenino , Duplicación de Gen , Pruebas Genéticas , Hospitales Psiquiátricos , Humanos , Hibridación Fluorescente in Situ , Discapacidad Intelectual/diagnóstico , Discapacidad Intelectual/etiología , Masculino , Persona de Mediana Edad , Países Bajos , SíndromeRESUMEN
OBJECTIVE: In chorionic villus sampling (CVS) the chromosome analysis is inconclusive in 1-2% of the samples. In many cases follow-up amniocentesis is performed. Fetal nucleated red blood cells (FNRBCs) are present in washings of chorionic villus samples. We wanted to establish whether analysis of these true fetal cells, using fluorescence in situ hybridization (FISH), could support the CVS karyotype. METHODS: We analysed washings of first trimester chorionic villi from non-mosaic 45,X (n=6) and full trisomy 18 cases (n=7). FNRBCs were identified by immunostaining and FISH was performed with chromosome-specific probes for X, Y and 18. RESULTS: In all 13 samples FNRBCs were present (between 4 and 30 cells per sample). Five cases of monosomy X showed one X signal in 89-100% of the nuclei; in the other case 50% of the nuclei displayed one signal. In the trisomy 18 cases three spots were seen in 60-100% of the cells. CONCLUSION: The CVS aneuploidy was confirmed in FNRBCs in all samples, so FISH on FNRBCs can be used in cases of non-mosaic numerical chromosomal abnormalities. This test can confirm a CVS diagnosis of monosomy X or trisomy 18 and thus minimize the risk for false-positive diagnoses. An additional invasive test may be prevented.
Asunto(s)
Aneuploidia , Núcleo Celular/ultraestructura , Muestra de la Vellosidad Coriónica , Eritrocitos/ultraestructura , Sangre Fetal/citología , Hibridación Fluorescente in Situ , Cromosomas Humanos Par 18 , Femenino , Edad Gestacional , Hemoglobina E/análisis , Humanos , Monosomía , Embarazo , Trisomía , Cromosoma X , Cromosoma YRESUMEN
Chorionic villus sampling (CVS) is an established invasive prenatal diagnostic method for the detection of fetal chromosome aberrations. In 1-2% the karyotype result of CVS is inconclusive and follow-up confirmation will be required. To avoid another invasive procedure we examined fetal nucleated red blood cells (NRBCs) from CVS washings for genetic analysis. We analysed the washings of 20 chorionic villi samples of male fetuses. Fetal NRBCs were immunostained by an antibody against embryonic haemoglobin (HbE). FISH was performed with probes specific for the X and Y chromosome and the nucleus was counterstained with DAPI. Cells positive for the antibody, as well as for DAPI, were collected and stored by a semi-automated microscope. An operator reviewed those cells for their FISH signals. In 19 out of 20 CVS washings we found nucleated cells positive for HbE together with XY FISH signals. In none of the washings HbE positive cells with two X signals were found. Our results indicate that anti-HbE is a very specific antibody for identifying fetal NRBCs. NRBCs from CVS washings can be used as an additional fetal tissue for first trimester prenatal diagnosis.
Asunto(s)
Muestra de la Vellosidad Coriónica/normas , Aberraciones Cromosómicas/diagnóstico , Eritroblastos/citología , Enfermedades Fetales/diagnóstico , Anticuerpos/sangre , Aberraciones Cromosómicas/sangre , Trastornos de los Cromosomas , Femenino , Sangre Fetal/citología , Enfermedades Fetales/sangre , Hemoglobina Fetal/inmunología , Humanos , Hibridación Fluorescente in Situ , Masculino , Valor Predictivo de las Pruebas , Embarazo , Valores de ReferenciaRESUMEN
Recently, much attention has been given to subtelomeric chromosomal rearrangements as important aetiological factors leading to idiopathic mental retardation. However, detection of these aberrations is difficult, mostly due to technical limitations and lack of genotype-phenotype relationships. We report on a family with a history suggestive of segregation of a chromosomal anomaly. In two mildly mentally retarded sisters with a similar phenotype consisting of obesitas, skin atrophy of the lower limbs and mild facial dysmorphisms, a subtle unbalanced cryptic translocation (46,XX,der(13)t(8;13)(q24.3;q34)) was detected on routine cytogenetic investigation followed by additional FISH studies. The translocation originated from the mother.
Asunto(s)
Cromosomas Humanos Par 13/genética , Cromosomas Humanos Par 8/genética , Discapacidad Intelectual/genética , Translocación Genética , Adulto , Atrofia/genética , Atrofia/patología , Bandeo Cromosómico , Sondas de ADN , Asimetría Facial/genética , Asimetría Facial/patología , Femenino , Humanos , Hibridación Fluorescente in Situ , Discapacidad Intelectual/patología , Cariotipificación , Masculino , Obesidad/genética , Obesidad/patología , Linaje , Telómero/genéticaRESUMEN
The DAZ genes are candidate fertility factors that lie within the human Y chromosome's AZFc region, whose deletion is a common cause of spermatogenic failure. The number of DAZ genes has been difficult to determine, in part because the nucleotide sequences of the DAZ genes are nearly identical. Here, fluorescence in situ hybridization and characterization of BAC clones revealed four full-length DAZ genes on the human Y chromosome. They exist in two clusters, each comprising an inverted pair of DAZ genes (3' <-- 5'::5' --> 3'). Analysis of genomic sequences and testicular transcripts suggested that three or four DAZ genes are translated. Each gene contains at least seven tandem copies of a previously described, 2.4-kb repeat unit that encodes 24 amino acids. In addition, two DAZ genes contain tandem copies of a 10.8-kb repeat unit that encodes the RNA-binding domain, which appears to be multimerized in some DAZ proteins. Combining our present results with previous studies, we can reconstruct several steps in the evolution of the DAZ genes on the Y chromosome. In the ancestral Y-chromosomal DAZ gene, amplification of both intragenic repeats began before the human and cynomolgus (Old World) monkey lineages diverged. During subsequent evolution, an inverted duplication of this modified gene occurred. Finally, the resulting two-gene cluster was duplicated, generating the two-cluster/four-gene arrangement found on modern human Y chromosomes.
Asunto(s)
Familia de Multigenes , Proteínas de Unión al ARN/genética , Cromosoma Y/genética , Secuencia de Bases , Southern Blotting , Cromosomas Artificiales de Levadura , Cartilla de ADN/química , Proteína 1 Delecionada en la Azoospermia , Electroforesis en Gel de Campo Pulsado , Fibroblastos , Duplicación de Gen , Biblioteca Genómica , Humanos , Hibridación Fluorescente in Situ , Interfase , Masculino , Datos de Secuencia Molecular , Reacción en Cadena de la Polimerasa , Proteínas de Unión al ARN/química , Secuencias Repetitivas de Ácidos Nucleicos , Mapeo Restrictivo , Secuencias Repetidas en TándemRESUMEN
We report on a boy with an interstitial deletion of the long arm of chromosome 2 with breakpoints in chromosome bands q23 and q24.3. Main features were low-set and malformed ears, digital anomalies and congenital heart defects, which have also been reported in most of the previously described cases. A comparison of the features of the present patient with those in previously reported cases suggests the deletion 2q23q24 to be a clinically recognizable syndrome.
Asunto(s)
Anomalías Múltiples/genética , Deleción Cromosómica , Cromosomas Humanos Par 2 , Fragilidad Cromosómica , Humanos , Recién Nacido , Cariotipificación , Masculino , SíndromeRESUMEN
Classical cytogenetics has a low resolving power and allows analysis of dividing cells only. In fluorescence in situ hybridization (FISH), a DNA fragment is stained with a fluorescent marker, after which this fragment is brought into contact with a patient's DNA. The stained fragment can bind to a corresponding fragment, revealing its presence or absence. Using FISH, every desired DNA sequence (from a whole chromosome to one gene) can be stained. In this way it is also possible to diagnose microdeletion syndromes, such as the Williams syndrome, the DiGeorge syndrome and submicroscopic chromosome anomalies that play a part in mental handicaps. FISH also allows analysis of non-dividing cells. In this way it is possible for instance rapidly to examine uncultured amniotic fluid cells for the commoner trisomies or to find foetal erythrocytes in a pregnant woman's blood. It is also possible to demonstrate tumour-specific breaking points. By application of FISH to microarrays it is possible to study a large number of genes simultaneously for the presence of a particular number of DNA sequences linked to a clinical abnormality.
Asunto(s)
Aberraciones Cromosómicas/diagnóstico , Aberraciones Cromosómicas/genética , Análisis Mutacional de ADN , Hibridación Fluorescente in Situ/estadística & datos numéricos , Deleción Cromosómica , Trastornos de los Cromosomas , Análisis Citogenético , Sondas de ADN , Humanos , Repeticiones de Microsatélite , Síndrome , Translocación Genética , Trisomía/diagnóstico , Trisomía/genéticaAsunto(s)
Anomalías Múltiples/genética , Cromosomas Humanos Par 11/genética , Cromosomas Humanos Par 6/genética , Translocación Genética , Anomalías Craneofaciales/genética , Facies , Femenino , Cardiopatías Congénitas/genética , Humanos , Lactante , Masculino , Linaje , Síndrome , Trombocitopenia/genéticaRESUMEN
Recently five patients with an Albright hereditary osteodystrophy (AHO)-like phenotype were reported to have a subtelomeric deletion of the long arm of chromosome 2. These patients showed a striking resemblance to a number of patients from a large pedigree known to us for a long time. After molecular confirmation of a subtelomeric deletion in one patient, FISH analysis was used and a cryptic translocation between the long arms of chromosomes 2 and 8, t(2;8)(q37.3;q24.3), was detected. Remarkably, five proven and 10 probable cases with a 2qter deletion were found in the family, but none with an 8qter deletion. This was not explained by increased fetal loss. The major clinical characteristics of terminal 2q deletion are a short, stocky build, round face, sparse hair, deeply set eyes, bulbous nose, thin vermilion border, brachymetaphalangism, seizures, and developmental delay. A specific behavioural phenotype consisting of periods of hyperkinesia and aggression can develop with age. The overall phenotype is sufficiently characteristic to allow clinical recognition. The cytogenetic and molecular studies did not narrow down the common deleted region. Both testing of additional 2q markers and characterisation of other AHO-like patients with 2q37 microdeletions may help to define the candidate gene region.
Asunto(s)
Cromosomas Humanos Par 2 , Cromosomas Humanos Par 8 , Displasia Fibrosa Poliostótica/genética , Translocación Genética , Adolescente , Adulto , Niño , Deleción Cromosómica , Femenino , Displasia Fibrosa Poliostótica/diagnóstico por imagen , Humanos , Hibridación Fluorescente in Situ , Cariotipificación , Masculino , Linaje , Fenotipo , RadiografíaRESUMEN
We report on a 4-year-old child with psychomotor retardation, general hypotonia and only mild dysmorphic features. Her chromosome constitution was 46,XX, t (6;9) (q27;q22.1), dup (9) (q21.2q22.1). This de novo interstitial duplication was confirmed using fluorescence in situ hybridisation (FISH) with band-specific probes. This is the second report of a patient with an interstitial duplication of this region of the long arm of chromosome 9. It is concluded that in a child with an abnormal phenotype and a de novo (apparently) balanced translocation, the possibility of a small duplication or deletion should be considered.
Asunto(s)
Cromosomas Humanos Par 6 , Cromosomas Humanos Par 9 , Cara/anomalías , Duplicación de Gen , Trastornos Psicomotores/genética , Translocación Genética , Preescolar , Femenino , Humanos , Hibridación Fluorescente in Situ , CariotipificaciónRESUMEN
In this study we evaluated the performance of a system for the enrichment, identification and analysis of fetal cells in maternal peripheral blood. Blood samples were collected from women after chorionic villus sampling and enriched for the presence of nucleated erythrocytes using a three-step procedure, namely: (a) centrifugation to separate nucleated red blood cells (NRBCs) from the majority of red blood cells (RBCs) and white blood cells (WBCs); (b) selective lysis of the remaining maternal RBCs; (c) separating the NRBCs from the remaining WBCs in a three-layer density gradient. Fetal cells were identified by using a monoclonal antibody against the gamma-chain of fetal haemoglobin (anti-HbF) and a nuclear stain (DAPI). Additionally, to further increase the specificity of the identification, and to eliminate some of the undesired staining by maternal leukocytes, a fluorescent antibody (CD45) was added. The sex chromosome complement of the cells was determined by fluorescence in situ hybridization (FISH) with X and Y-specific probes and the results were compared with the karyotypes obtained after analysis of chorionic villi. Using the described method, in all cases where the woman was carrying a male fetus (n=18) at least one XY cell was found, while no male cells were found in women carrying a female fetus. However, in the majority of cases with a male fetus (n=11) female HbF positive cells were found indicating the presence of maternal nucleated erythrocytes. The study demonstrates that the combination of anti-HbF and CD45 is a useful, but not fully specific, marker for fetal NRBCs and that additional markers are needed.
Asunto(s)
Separación Celular/métodos , Eritrocitos , Sangre Fetal/citología , Diagnóstico Prenatal/métodos , Anticuerpos Monoclonales , Núcleo Celular , Centrifugación , Centrifugación por Gradiente de Densidad , Eritrocitos/ultraestructura , Femenino , Hemoglobina Fetal/análisis , Hemólisis , Humanos , Hibridación Fluorescente in Situ , Antígenos Comunes de Leucocito/análisis , Masculino , Embarazo , Sensibilidad y Especificidad , Cromosomas SexualesAsunto(s)
Proteínas de Ciclo Celular/genética , Cromosomas Humanos Par 20 , ADN Complementario/análisis , Proteínas de Unión al ADN/genética , Proteínas de Saccharomyces cerevisiae , Secuencia de Aminoácidos , Proteínas de Ciclo Celular/aislamiento & purificación , Proteínas de Ciclo Celular/metabolismo , Clonación Molecular , Secuencia Conservada , AMP Cíclico/metabolismo , Proteínas de Unión al ADN/aislamiento & purificación , Proteínas de Unión al ADN/metabolismo , Proteínas Fúngicas/genética , Humanos , Hibridación Fluorescente in Situ , Masculino , Datos de Secuencia Molecular , Fosforilación , Homología de Secuencia de Aminoácido , Testículo/fisiologíaRESUMEN
We report a case of fetal triploidy in which fetal nucleated red blood cells were isolated from the maternal peripheral circulation at 12 weeks' gestation. FISH analysis with X and Y specific probes revealed three hybridization signals for the X chromosomes in 14 cells. The karyotype as established after CVS was shown to be 69,XXX. Two other non-invasive first-trimester screening methods were also evaluated. The serum markers pregnancy-associated plasma protein A (PAPP-A) and the free beta-chain of chorionic gonadotrophin (free beta-hCG) were both shown to be decreased in the same blood sample. An enlarged nuchal translucency (5 mm > or =95th centile) was seen at 13+2 weeks of gestation.
Asunto(s)
Biomarcadores/sangre , Enfermedades Fetales/diagnóstico , Poliploidía , Diagnóstico Prenatal , Adulto , Femenino , Enfermedades Fetales/sangre , Enfermedades Fetales/genética , Humanos , Hibridación Fluorescente in Situ , Embarazo , Primer Trimestre del EmbarazoRESUMEN
Expansions of trinucleotide CAG repeats have been demonstrated in at least eight neurodegenerative disorders, and suggested to occur in several others, including bipolar disorder and schizophrenia. Chromosome 18 loci have been implicated in bipolar disorder pedigrees by linkage analysis. To address this putative link between chromosome 18 CAG trinucleotide repeats and neuropsychiatric illness, we have screened a chromosome 18 cosmid library (LL18NCO2" AD") and identified 14 novel candidate loci. Characterisation of these loci involved repeat flank sequencing, estimation of polymorphism frequency and mapping using FISH as well as radiation hybrid panels. These mapped trinucleotide loci will be useful in the investigation of chromosome 18 in neurodegenerative or psychiatric conditions, and will serve to integrate physical and radiation hybrid maps of chromosome 18.
Asunto(s)
Mapeo Cromosómico , Cromosomas Humanos Par 18 , Repeticiones de Trinucleótidos , Secuencia de Bases , Cartilla de ADN , Humanos , Células Híbridas , Trastornos Mentales/genética , Homología de Secuencia de Ácido Nucleico , Lugares Marcados de SecuenciaRESUMEN
The chance of a male with severe oligozoospermia or azoospermia achieving a pregnancy has undergone a revolutionary increase with the introduction of the intracytoplasmic sperm injection technique (ICSI). However, since ICSI circumvents part of the natural sperm selection mechanisms, the possible transmission of genetic defects to the offspring is a major concern. Cytogenetic analysis is a relatively simple technique to identify at least the carriers of a chromosomal aberration before starting the ICSI procedure. In order to assess the frequency of chromosomal aberrations in male ICSI candidates, we have performed a nationwide cytogenetic study. Of the 1792 males examined, 72 (4.0%) revealed a chromosomal aberration, and one individual even had two. Numerical sex chromosomal aberrations and Robertsonian translocations predominated, followed by reciprocal translocations, inversions and supernumerary marker chromosomes. The different implications, in case a chromosomal aberration is encountered prior to ICSI, are discussed.
Asunto(s)
Fertilización In Vitro/métodos , Infertilidad Masculina/genética , Aberraciones Cromosómicas , Estudios de Cohortes , Humanos , Masculino , Países BajosRESUMEN
AIMS: Chromosomal gains and losses were surveyed by comparative genomic hybridisation (CGH) in a series of colorectal adenomas and carcinomas, in search of high risk genomic changes involved in colorectal carcinogenesis. METHODS: Nine colorectal adenomas and 14 carcinomas were analysed by CGH, and DNA ploidy was assessed with both flow and image cytometry. RESULTS: In the nine adenomas analysed, an average of 6.6 (range 1 to 11) chromosomal aberrations were identified. In the 14 carcinomas an average of 11.9 (range 5 to 17) events were found per tumour. In the adenomas the number of gains and losses was in balance (3.6 v 3.0) while in carcinomas gains occurred more often than losses (8.2 v 3.7). Frequent gains involved 13q, 7p, 8q, and 20q, whereas losses most often occurred at 18q, 4q, and 8p. Gains of 13q, 8q, and 20q, and loss of 18q occurred more often in carcinomas than in adenomas (p = 0.005, p = 0.05, p = 0.05, and p = 0.02, respectively). Aneuploid tumours showed more gains than losses (mean 9.3 v 4.9, p = 0.02), in contrast to diploid tumours where gains and losses were nearly balanced (mean 3.1 v 4.1, p = 0.5). CONCLUSIONS: The most striking difference between chromosomal aberrations in colorectal adenomas and carcinomas, as detected by CGH, is an increased number of chromosomal gains that show a nonrandom distribution. Gains of 13q and also of 20q and 8q seem especially to be involved in the progression of adenomas to carcinomas, possibly owing to low level overexpression of oncogenes at these loci.
Asunto(s)
Adenoma/genética , Adenoma/patología , Carcinoma/genética , Aberraciones Cromosómicas/genética , Neoplasias Colorrectales/genética , Neoplasias Colorrectales/patología , Adulto , Anciano , Anciano de 80 o más Años , Aneuploidia , Diploidia , Progresión de la Enfermedad , Femenino , Citometría de Flujo , Humanos , Procesamiento de Imagen Asistido por Computador , Neoplasias Hepáticas/genética , Neoplasias Hepáticas/secundario , Masculino , Persona de Mediana Edad , Estadificación de Neoplasias , Hibridación de Ácido Nucleico/métodos , Estadísticas no ParamétricasRESUMEN
We identified 10 members of a single family with mental retardation and microcephaly, one member having macrocephaly instead. The pedigree was best compatible with the segregation of a small translocation, despite results of previous cytogenetic studies in several relatives being apparently normal. Eventually high resolution and fluorescence in situ hybridization studies in the parents allowed the detection of a balanced translocation between 5qter and 6qter, and of its unbalanced products in the offspring. The pertinent findings from the family are briefly compared with the clinical findings in patients from the literature with either a duplication or deletion of 5q35-ter, or a duplication or deletion of 6q27-ter.
Asunto(s)
Anomalías Múltiples/genética , Cromosomas Humanos Par 5/genética , Cromosomas Humanos Par 6/genética , Translocación Genética , Niño , Preescolar , Femenino , Humanos , Hibridación Fluorescente in Situ , Discapacidad Intelectual , Cariotipificación , Masculino , Microcefalia , LinajeRESUMEN
We have identified Celsr1, a gene that encodes a developmentally regulated vertebrate seven-pass transmembrane protein. The extracellular domain of Celsr1 contains two regions each with homology to distinct classes of well-characterized motifs found in the extra-cellular domains of many cell surface molecules. The most N-terminal region contains a block of contiguous cadherin repeats, and C-terminal to this is a region containing seven epidermal growth factor-like repeats interrupted by two laminin A G-type repeats. Celsr1 is unique in that it contains this combination of repeats coupled to a seven-pass transmembrane domain. As part of the characterization of the Celsr1 gene, we have determined its chromosomal map location in both mouse and human. The European Collaborative Interspecific Backcross (EUCIB) and BXD recombinant inbred strains were used for mapping Celsr1 cDNA clones in the mouse, and fluorescence in situ hybridization was used to map human Celsr1 cosmid clones on metaphase chromosomes. We report that Celsr1 maps to proximal mouse Chromosome 15 and human chromosome 22qter, a region of conserved synteny. Reverse transcriptase-polymerase chain reaction analysis and in situ hybridization were used to determine the spatial restriction of Celsr1 transcripts in adult and embryonic mice. The results presented here extend our previous finding of expression of the Celsr1 receptor in the embryo and show that expression continues into adult life when expression in the brain is localized principally in the ependymal cell layer, choroid plexus, and the area postrema.