RESUMEN
Presentamos los hallazgos cromosómicos de una mujer de cuatro años de edad con trombocitopenia. El cariotipo demostró un 1(7) q(10) como una posible deleción en 11q23 y un cuestionable rearreglo en 9p. Los estudios por FISH de ambas interfase del núcleo y metafase de la célula, usando la fase de reposo MLL y caracterización de la prueba instrumental en el gen MLL, el cual fue encriptado por análisis citogenético convencional. Específicamente, el patrón FISH fue consistente con una inserción de la región 5' del gen MLL dentro de un cromosoma 4 hacia la banda q21, mas estrechamente una variante 1(4;11) (q 21;g23). Este caso ejemplifica la importancia del FISH y su consiguiente caracterización de casos precursores B-cell all, sin algún significado pronóstico de anormalidad cromosómica.
We present the chromosome findings in a 4-year-old female with thrombocytopenia. The karyotype showed an i(7)(q10) as well as a possible deletion on 11q23 and a questionable rearrangement on 9p. FISH studies on both interphase nuclei and metaphase cells using the MLL break apart rearrangement probe were instrumental in the characterization of an MLL gene rearrangement , which was cryptic by conventional cytogenetic analysis. Specifically, the FISH pattern was consistent with an insertion of the 5' region of the MLL gene into one chromosome 4 at band q21, most likely a variant t(4;11)(q21;q23). This case exemplifies the importance of FISH in the further characterization of precursor B-cell ALL cases without any apparent prognostically significant chromosome abnormalities.
Asunto(s)
Humanos , Femenino , Preescolar , Leucemia-Linfoma Linfoblástico de Células Precursoras , TrombocitopeniaRESUMEN
We report the chromosomal findings in a 4-year-old female with precursor B-cell acute lymphoblastic leukemia (ALL). The diagnostic karyotype showed an isochromosome 7q, i(7)(q10), as well as questionable rearrangements on 9p and 11q. Fluorescence in situ hybridization (FISH) studies on both interphase and metaphase cells using the MLL "break-apart" and the centromeric chromosome 4 probes were instrumental in the characterization of an MLL gene rearrangement, which was cryptic by conventional cytogenetic analysis. Specifically, the FISH pattern was consistent with an insertion of the 5' region of the MLL gene into chromosome 4 at band q21, most likely a variant t(4;11)(q21;q23). This is the second case of FISH detection of an ins(4;11) in ALL. Our case exemplifies the importance of FISH in the further characterization of precursor B-cell ALL cases without any apparent prognostically significant chromosomal abnormalities.
Asunto(s)
Linfoma de Burkitt/genética , Cromosomas Humanos Par 11 , Cromosomas Humanos Par 4 , Leucemia-Linfoma Linfoblástico de Células Precursoras/genética , Translocación Genética , Linfoma de Burkitt/patología , Preescolar , Bandeo Cromosómico , Femenino , N-Metiltransferasa de Histona-Lisina , Humanos , Hibridación Fluorescente in Situ , Cariotipificación , Mutagénesis Insercional , Proteína de la Leucemia Mieloide-Linfoide/genética , Leucemia-Linfoma Linfoblástico de Células Precursoras/patologíaRESUMEN
Hereditary haemochromatosis (HFE) is a recessive genetic disease of iron overload which has been shown by linkage analysis to reside on the short arm of chromosome 6, close to the major histocompatibility complex (MHC). Positional cloning of the putative HFE locus has been hampered, in part, by the lack of a structural alteration on 6p. In this report, we describe a pedigree with HFE which carries a balanced paracentric inversion of chromosome 6, inv(6)(p21.1p23), a rarely reported chromosomal rearrangement in this region. We have determined the inheritance of the chromosome harbouring the inversion, which segregates as an HFE chromosome. Because the HFE locus has been mapped distal to the HLA-F class I locus at 6p21.3, the breakpoints associated with this chromosomal rearrangement may provide a significant genomic landmark for positional cloning of the HFE gene.
Asunto(s)
Inversión Cromosómica , Cromosomas Humanos Par 6/genética , Hemocromatosis/genética , Adulto , Mapeo Cromosómico , Femenino , Marcadores Genéticos , Antígenos HLA/genética , Hemocromatosis/terapia , Humanos , Repeticiones de Microsatélite/genética , Linaje , Reacción en Cadena de la PolimerasaRESUMEN
Hemizygous deletion of 3p25-pter is associated with a phenotype of profound growth failure, microcephaly, characteristic facial changes, and mental retardation. Since the severity may be quite variable, we have studied 3 cases of del 3p25-pter to define the clinical manifestations and the critical chromosome region for phenotypic expression. The patient we now report died at age 6 months and provided an opportunity for a detailed necropsy analysis for only the second time in a del(3p) patient. He had marked hypoplasia of all organs, hypomyelination of white matter, and multiple renal cortical microcysts. Ordered genomic markers from the distal regions of chromosome 3p aided in determining the parent of origin of each deletion and in defining the boundaries of the deleted chromosomal segments. The deleted markers distal to the RAF1 oncogene in 2 of the 3 patients were consistently hemizygous. One patient had an interstitial deletion based on evidence of diploid inheritance of one of the most distal loci (D3S17). Available genetic linkage maps suggest that the deletion spans at least 19 centimorgans (cM).
Asunto(s)
Anomalías Múltiples/genética , Deleción Cromosómica , Cromosomas Humanos Par 3 , Cara/anomalías , Insuficiencia de Crecimiento/genética , Femenino , Humanos , Hibridación Fluorescente in Situ , Recién Nacido , Discapacidad Intelectual/genética , Cariotipificación , Masculino , Microcefalia/genética , Linaje , Fenotipo , Polimorfismo de Longitud del Fragmento de RestricciónRESUMEN
We describe a child with multiple anomalies and severe retardation with dup 7pter-p15.1 and del 7q36-qter as a result of a parental pericentric inversion of chromosome 7. The pericentric inversion was found in family members in 3 generations with 9 liveborn children who had severe anomalies probably associated with imbalances of chromosome 7.
Asunto(s)
Aberraciones Cromosómicas/genética , Deleción Cromosómica , Inversión Cromosómica , Cromosomas Humanos Par 7 , Discapacidad Intelectual/genética , Familia de Multigenes , Niño , Aberraciones Cromosómicas/patología , Aberraciones Cromosómicas/fisiopatología , Trastornos de los Cromosomas , Femenino , Humanos , Discapacidad Intelectual/patología , Discapacidad Intelectual/fisiopatología , LinajeRESUMEN
Five matings to a dir ins (6;2)(q16;q31q33) carrier have produced a high frequency (42%) of offspring with unbalanced karyotypes. Five children have the derivative chromosome 2 resulting in del (2)(q31q33) and one individual received the derivative chromosome 6 leading to dup (2)(q31q33). The findings associated with the deletion include pre- and postnatal growth retardation, developmental delay, minor facial anomalies, seizures, complex structural heart defects, and limb deficiency. Autopsy of one individual showed complex brain malformations including hydrocephalus secondary to obstruction of the foramina of Monro, extensive heterotopias and polymicrogyria, and an unusual form of total anomalous pulmonary venous return. We compare the findings in these children to those of previously reported cases and construct an overview of the range of anomalies. Apparently, no other individual with dup (2)(q31q33) has been described. We compare the physical peculiarities of our patient with those of individuals with duplications of overlapping regions of 2q.
Asunto(s)
Anomalías Múltiples/genética , Encéfalo/anomalías , Aberraciones Cromosómicas , Cromosomas Humanos Par 2 , Cardiopatías Congénitas/genética , Deformidades Congénitas de las Extremidades , Niño , Preescolar , Deleción Cromosómica , Femenino , Humanos , Lactante , Recién Nacido , Cariotipificación , Masculino , Linaje , ConvulsionesRESUMEN
We report a mother and son with a deletion at 18q22.3. Both have the typical manifestations of the 18q- syndrome. In addition, both have an action tremor which became apparent in childhood. The mother subsequently developed chorea and dysmetria in late adolescence. Magnetic resonance imaging of their brains showed poor myelination of the central white matter tracts with relatively normal myelination of the corpus callosum. We propose that these neurologic findings are most likely due to a failure of expression of the myelin basic protein gene.
Asunto(s)
Anomalías Múltiples/genética , Encéfalo/anomalías , Deleción Cromosómica , Cromosomas Humanos Par 18 , Adulto , Encéfalo/patología , Oído/anomalías , Femenino , Humanos , Lactante , Imagen por Resonancia Magnética , Masculino , Proteína Básica de Mielina/genética , Temblor/genéticaRESUMEN
Hypermodal chromosomal spreads occurred significantly more frequently in lymphocytes from couples with recurrent spontaneous abortion than from comparison populations. Previously, we reported a similarly increased frequency in couples with aneuploid offspring. Considering the frequency of aneuploidy among first trimester spontaneous abortions, we suggest that there may be a sub-population of persons predisposed to non-disjunction among couples with reproductive wastage.
Asunto(s)
Aborto Habitual/genética , Aneuploidia , No Disyunción Genética , Adulto , Células Cultivadas , Bandeo Cromosómico , Femenino , Humanos , Linfocitos/ultraestructura , Masculino , Edad Materna , Mitosis , Edad Paterna , EmbarazoRESUMEN
Blindness due to congenital falciform retinal folds and severe mental retardation were present in a male with an interstitial deletion, 46,XY, del(13) (q31.2q32.3).
Asunto(s)
Anomalías Múltiples/genética , Ceguera/genética , Deleción Cromosómica , Cromosomas Humanos 13-15 , Discapacidad Intelectual/genética , Adulto , Ceguera/congénito , Niño , Bandeo Cromosómico , Dermatoglifia , Femenino , Humanos , Cariotipificación , MasculinoRESUMEN
The Q-band polymorphism of chromosome 21 permits assignment of the origin of meiotic nondisjunction by parent and meiotic division in a certain proportion of cases. We have compiled all reports through 1982 (including earlier studies using structural abnormality) and have shown that maternal origin accounts for 80% and paternal origin for 20% of trisomic cases. The ratio of first:second meiotic errors among the maternal cases was 80:20 and 60:40 among the paternal cases. Considering maternal and paternal first and second meiotic errors, we showed no differences of either mean maternal or paternal age, though mean maternal age is about 5 yr higher than that of the general population. Comparison of results of six studies from five countries showed similar frequencies by parent and meiotic division with the possible exception of one study from the northeastern United States. The causative role of simply advancing maternal age in nondisjunction is questioned.