RESUMEN
Critical cytogenetic (re)evaluation of 2 of our own cases of tricho-rhino-phalangeal syndrome II (TRP II), or Langer-Giedion syndrome (LGS), and 10 cases from the literature, suggests that the shortest region of overlap of the 8q deletion is a part of band q24.1. This region is assumed to be causally related to this syndrome, and possibly also to TRP I syndrome which, therefore, may not be a causally separate entity.
Asunto(s)
Anomalías Múltiples/genética , Deleción Cromosómica , Cromosomas Humanos 6-12 y X , Anomalías Múltiples/clasificación , Bandeo Cromosómico , Humanos , Cariotipificación , SíndromeRESUMEN
Retrospective analysis of "routine" chromosome preparations from 2 patients with Fanconi anemia and 2 others with ataxia-teleangiectasia showed increased chromosome breakage and a tendency to premature centromere division (PCD) with special reference to early separation of the large acrocentric (13-15) chromosomes. The findings suggest that PCD may be a manifestation of chromosome instability related to potential malignancy.
Asunto(s)
Centrómero/genética , Aberraciones Cromosómicas/genética , Cromosomas Humanos 13-15 , Mitosis/genética , Adolescente , Ataxia Telangiectasia/complicaciones , Ataxia Telangiectasia/genética , Estudios de Casos y Controles , Niño , Aberraciones Cromosómicas/diagnóstico , Bandeo Cromosómico , Trastornos de los Cromosomas , Anemia de Fanconi/complicaciones , Anemia de Fanconi/genética , Femenino , Muerte Fetal/complicaciones , Muerte Fetal/genética , Feto/anomalías , Humanos , Embarazo , Estudios RetrospectivosRESUMEN
The fact that probably less than 1% of Rett syndrome cases are familial speaks in favor of a spontaneous mutation as the most common cause of Rett syndrome. However, the few familial cases (about 10) described in the literature, the elevated consanguinity rate in parents of Rett patients (2.4% vs. 0.5%), and the existence of "formes frustes" in relatives of Rett girls, suggest that inheritance must exist. A model based on a hypothetical form of inheritance, namely allelic and non-allelic metabolic interference, fits almost all available data, as well as the exclusive occurrence in females without increased abortion rate.
Asunto(s)
Modelos Genéticos , Síndrome de Rett/genética , Alelos , Consanguinidad , Femenino , Genotipo , Humanos , Masculino , Mutación , Fenotipo , Cromosoma XRESUMEN
We report on a boy with mosaic trisomy 15. The clinical manifestations are compared with those of the few cases reported up to now. A clinical syndrome is delineated consisting of a characteristic shape of the nose and other minor craniofacial anomalies, as well as typical deformities of the hands and feet. Different degrees of mosaicism may explain the more or less severe manifestations in individual patients.
Asunto(s)
Anomalías Múltiples/genética , Cromosomas Humanos Par 15 , Mosaicismo , Trisomía , Adulto , Células Cultivadas , Preescolar , Femenino , Fibroblastos/citología , Humanos , Masculino , Embarazo , SíndromeRESUMEN
An X chromosome gene is assumed to be responsible for the cause of Rett syndrome (RS). However, new genealogical observations suggest involvement of autosomal recessive gene(s) as well, at least in familial cases. To account for these and other recent observations, the theoretical model presented in 1990 by the authors of this paper is applied to the calculation of gene frequencies. Observed frequencies of sporadic and familial cases of RS are used, taking into account genetic drift in inbreeded areas. Moreover, an attempt is made to use the proportion of RS variants in familial and sporadic cases for the explanation of so called 'formes frustes', and as evidence for the existence of female as well as male carriers. The estimated frequency of the recessive autosome mutation, or possibly a frequent polymorphism, is 22.5%.
Asunto(s)
Frecuencia de los Genes , Síndrome de Rett/genética , Cromosoma X , Alelos , Femenino , Genes Recesivos , Tamización de Portadores Genéticos , Impresión Genómica , Genotipo , Humanos , Masculino , Modelos GenéticosRESUMEN
We present clinical and cytogenetic data of a one year old boy with partial monosomy for both 21q and 18p, resulting from a de novo unbalanced translocation. The initial diagnosis of a seemingly full monosomy 21 was revised after fluorescence in situ hybridisation (FISH) with whole chromosome painting probes and a locus-specific chromosome 21 probe. The karyotype was reinterpreted as 45,XY,der(18)t(18;21)(p11.2;q22.1),-21. This karyotype, to our knowledge, has not been previously described. The boy presented with a spectrum of clinical features previously described for (partial) monosomy 18p only, for monosomy 21q only, or for both of these aneusomies. The radiological finding of a neuronal migration disorder with localised polymicrogyria (cortical dysplasia) has not been described for either monosomy before.
Asunto(s)
Movimiento Celular/genética , Cromosomas Humanos Par 18 , Cromosomas Humanos Par 21 , Monosomía/genética , Neuronas/citología , Translocación Genética , Anomalías Múltiples/genética , Corteza Cerebral/patología , Humanos , Hibridación Fluorescente in Situ , Recién Nacido , Cariotipificación , Imagen por Resonancia Magnética , MasculinoRESUMEN
The sequence of centromere division was analysed in 100 selected late metaphase mitoses of cultured human amniotic cells. The pattern obtained was very similar to that of the previously studied lymphocytes; Chromosomes 18, 12, 17, 5 and X proved to be early dividing, and the acrocentrics were the last to separate in both amniotic cells and blood lymphocytes.
Asunto(s)
Centrómero , Cromosomas , Metafase , Amnios , Células Cultivadas , Humanos , Linfocitos/citologíaRESUMEN
The Roberts-SC phocomelia syndrome is a rare autosomal recessive inherited disorder clinically manifested by tetraphocomelia, pre- and postnatal growth retardation, and craniofacial abnormalities (skull, eyes, lip, and palate), accompanied at times by centromer puffing and splitting, renal abnormalities, heart defect, clitoral or penile enlargement, and bilateral corneal opacities. Mental retardation is common in surviving patients.
Asunto(s)
Anomalías Múltiples/genética , Aberraciones Cromosómicas/genética , Ectromelia/genética , Genes Recesivos/genética , Anomalías Múltiples/diagnóstico por imagen , Aborto Eugénico , Adulto , Centrómero/genética , Bandeo Cromosómico , Trastornos de los Cromosomas , Diagnóstico Diferencial , Ectromelia/diagnóstico por imagen , Femenino , Humanos , Recién Nacido , Embarazo , Síndrome , Ultrasonografía PrenatalAsunto(s)
Diagnóstico Prenatal , Aberraciones Cromosómicas Sexuales/genética , Adulto , Femenino , Humanos , Recién Nacido , Cariotipificación , Masculino , Embarazo , Cromosoma X , Cromosoma YAsunto(s)
Cromosomas Humanos 6-12 y X , Mosaicismo , Trisomía , Anomalías Múltiples/genética , Adolescente , Niño , Preescolar , Dermatoglifia , Humanos , Discapacidad Intelectual/genética , Masculino , SíndromeRESUMEN
Phenotypic abnormalities in individuals with balanced chromosome rearrangements can be caused by loss of function at the break points and consequent functional homozygosity for recessive genes. This has obvious implications in prenatal diagnosis. Relevant cases are presented and discussed. Mendelian disorders and possibly also disorders which are under polygenic control may be assigned to certain chromosome regions or bands by means of such translocations. Several assignments have been accomplished lately, the approach being much the same as with deletion mapping.
Asunto(s)
Mapeo Cromosómico , Tamización de Portadores Genéticos , Diagnóstico Prenatal , Translocación Genética , Adulto , Niño , Preescolar , Femenino , Humanos , Cariotipificación , Masculino , EmbarazoRESUMEN
Phenotypic features and functions known to depend on the presence of the Y chromosome or the H-Y antigen are discussed in relation to structural anomalies of the Y chromosome and other abnormalities of sexual and somatic development. Recent knowledge about molecular organization of constitutive heterochromatin in relation to the human Y is presented. An attempt is made at assigning different functions, genes and DNA sequences to different regions of the Y chromosome.
Asunto(s)
Cromosomas Humanos , Antígeno H-Y/genética , Cromosomas Sexuales , Cromosoma Y , Desarrollo Óseo , Aberraciones Cromosómicas , Bandeo Cromosómico , Mapeo Cromosómico , Disgenesia Gonadal/genética , Crecimiento , Humanos , Cariotipificación , Masculino , Mosaicismo , Odontogénesis , Fenotipo , Polimorfismo Genético , Análisis para Determinación del Sexo , Testículo/embriologíaRESUMEN
Human lymphoid cell cultures were treated with 2,2'-dithiodipyridine, a thiol reacting agent which produces SS bridges inside the living cells. After 1 to 4 h treatment chromosome preparations were made. The chromosomes acquired a peculiar segmentation along the chromatids. The results suggest that the alteration might arise from a direct reaction of the agent with special chromosomal proteins. The resistance of treated chromosomes to alkali-heat treatment used in C-banding technique was different from that of untreated chromosomes. This prefixational procedure seems to be advantageous in analysing both the chromosome organization and the banding mechanism.
Asunto(s)
Cromosomas , Cromátides , Disulfuros , Humanos , Cariotipificación , Linfocitos , Mitosis , Conformación Molecular , AzufreRESUMEN
The incidental finding of DM's, minutes, HSR's, PCC, and PCD in two completely unrelated cases--one is a prenatal diagnosis in a twin pregnancy complicated by hydramnios and feto-fetal exsanguination, the other is an adult Klinefelter patient--raises the question whether such findings are coincidental or whether there is a common denominator in such cases. Possible relationships between these phenomena and the observed cases are discussed.
Asunto(s)
Centrómero/ultraestructura , Aberraciones Cromosómicas , Trastornos de los Cromosomas , Cromosomas/ultraestructura , Enfermedades en Gemelos , Síndrome de Klinefelter/genética , Gemelos Dicigóticos , Gemelos , Adulto , Células Cultivadas , Femenino , Humanos , Recién Nacido , Cariotipificación , Linfocitos/citología , Masculino , Persona de Mediana Edad , Mitosis , EmbarazoRESUMEN
A decondensed site at band q26 of the X chromosome was found in a male baby with growth and developmental retardation and a dysmorphic syndrome, as well as in his pheno-typically normal mother, without using any special culture conditions.
Asunto(s)
Síndrome del Cromosoma X Frágil/genética , Discapacidad Intelectual/genética , Aberraciones Cromosómicas Sexuales/genética , Células Cultivadas , Mapeo Cromosómico , Femenino , Síndrome del Cromosoma X Frágil/patología , Humanos , Masculino , Mitosis , Cromosoma X/ultraestructuraRESUMEN
In a sister and a brother with striking similarity of facial dysplasias, severe disturbance of expressive speech, and mild mental retardation a partial trisomy of the long arm of chromosome 4 was identified as cause of these anomalies. The partial trisomy 4q was due to a balanced translocation between the chromosomes 1 and 4 in the father of both children.
Asunto(s)
Anomalías Múltiples/genética , Cromosomas Humanos Par 1 , Cromosomas Humanos Par 4 , Huesos Faciales/anomalías , Padre , Discapacidad Intelectual/genética , Translocación Genética/genética , Trisomía , Preescolar , Bandeo Cromosómico , Femenino , Humanos , Trastornos del Desarrollo del Lenguaje/genética , MasculinoRESUMEN
The centromere separation sequence was determined in the mitoses of 5 subjects with "balanced" D/D translocations. Similarly to the acrocentrics, also the D/D fusions belonged to the chromosomes the sister chromatids of which separated last in the late metaphase stage.
Asunto(s)
Cromosomas Humanos Par 13/ultraestructura , Cromosomas Humanos Par 14/ultraestructura , Cromosomas Humanos Par 15/ultraestructura , Translocación Genética , Centrómero/ultraestructura , Aberraciones Cromosómicas/genética , Bandeo Cromosómico , Trastornos de los Cromosomas , Anomalías Congénitas/genética , Femenino , Humanos , MasculinoRESUMEN
Reexamination with high resolution banding of the first ever published case of Langer-Giedion syndrome with 8q deletion as well as chromosome examination of a second case of this syndrome with different high resolution methods, confirmed our previous assumption of a terminal 8q involvement in the causation of TRP II syndrome.
Asunto(s)
Anomalías Múltiples/genética , Deleción Cromosómica , Cromosomas Humanos 6-12 y X/ultraestructura , Dedos/anomalías , Cabello/anomalías , Nariz/anomalías , Preescolar , Bandeo Cromosómico , Humanos , Masculino , SíndromeRESUMEN
Chromosomal findings in the majority of cases of TRP II (or Langer-Giedion) syndrome and in some cases of TRP I syndrome lead to the conclusion that the former is due to a deletion extending from 8q24.11 to 8q24.13 whereas the latter is caused by an even smaller deleted segment, namely 8q24.12. A case of tricho-rhino-phalangeal syndrome type I with a mosaic deletion of band 8q24.12 is described.
Asunto(s)
Anomalías Múltiples/genética , Huesos/anomalías , Cabello/anomalías , Nariz/anomalías , Niño , Deleción Cromosómica , Cromosomas Humanos Par 8 , Humanos , Masculino , Mosaicismo , SíndromeRESUMEN
Carrier detection and prenatal diagnosis of hemophilia A and B are possible with cloned factor-VIII:C- and factor-IX-gene-specific or linked probes which detect restriction fragment length polymorphisms (RFLPs). In this study, 12 hemophilia-A- and 5 hemophilia-B-families were studied to identify carriers and provide adequate genetic counselling to women who were heterozygous for one or more of the intragenic or linked DNA probes with respect to future pregnancies.