Inversiones cromosómicas (anomalías estructurales poco frecuentes) asociadas a fenotipo normal, dudoso y patológico / Chromosomal inversions (Slight structural anomalies) associated to normal, doubtfull and pathological phenotypes

Las inversiones son reordenamientos intracromosómicos originados por dos rupturas en un cromosoma seguidas de la reinserción del fragmento rotado en 180º. Dependiendo si involucra o no al centrómero pueden ser pericén tricas o paracéntricas. La incidencia es 0.09 a 0.49/1.000. Las inversiones son rearreglos estructurales aparentemente equilibrados, por lo que la mayoría de los individuos portadores tienen fenotipos normales y una minoría tienen fenotipos patológicos (probablemente por alteración en la secuencia de genes o variación en la función de éstos por efectos de cambio de posición). Se presentan tres casos de inversiones detectas por la técnica de Bandeo G y confirmadas por Hibridación In Situ Fluorescente (FISH). Caso 1: INVERSION PARACENTRICA FAMILIAR DEL CROMOSOMA 13 ASOCIADA A RETRASO MENTAL Y DISMORFIAS. El exhaustivo análisis del árbol genealógico y el estudio cromosómico al mayor número posible de individuos permitió confirmar la asociación inversión/fenotipo patológico en este grupo familiar. 13 de 17 miembros son portadores de inv(13)(q31q32)inh.ish inv(13)(q31q32) (wcp13+). Caso 2: INVERSION PARACENTRICA DEL CROMOSOMA 6 DE NOVO EN RECIEN NACIDO CON RETRASO MADURATIVO GLOBAL Y RETRASO DEL CRECIMIENTO INTRAUTERINO. En este caso no es posible adjudicar que, el fenotipo afectado se deba a la inversión. Cariotipo: 46,XY,add(6)(q21)dn.ish inv(6)(q21q27)(wcp6+). Caso 3: INVERSION PERICENTRICA DEL CROMOSOMA 12 EN OVODONANTE. Dicha inversión no parece tener efecto sobre el fenotipo, ya que es una paciente con coeficiente intelectual normal y no presenta malformaciones congénitas. Cariotipo: 46,XX,inv(12)(p12q14).ish inv(12) (p12q14)(wcp12+). Este reporte de casos muestra los tres fenotipos posibles de una inversión: patológico, dudoso y normal. Es el primer reporte de una inv(13) que confiera fenotipo patológico.

The inversions are intrachromosomal rearrangements which occur when a single chromosome undergoes two breaks and the region between it's rotates 180 degrees before rejoining. Depending on whether or not it include the centromere, they can be pericentric or paracentric. The incidence is 0.09 to 0.49/1,000. The inversions are apparently balanced structural rearrangements, so the most of the carrier individuals show normal phenotypes and a minority have pathological phenotypes (probably due to variation in their function due to changes in position). Three cases of inversions detected by the G Banding technique and confirmed by Fluorescence In Situ Hybridization (FISH) are presented. Case 1: FAMILIAL PARACENTRIC INVERSION OF CHROMOSOME 13 ASSOCIATED WITH MENTAL RETARDATION AND DISMORPHIA. The exhaustive analysis of the pedigree and the chromosomal study to the greatest possible number of individuals confirmed the inversion/pathological phenotype association in this family group. 13 of 17 members are carriers of inv(13)(q31q32)inh.ish inv(13)(q31q32)(wcp13+). Case 2: PARACENTRAL INVERSION DE NOVO OF CHROMOSOME 6 IN NEWBORN WITH GLOBAL MATURITY DELAY AND DELAY OF INTRAUTERINE GROWTH. In this case it is not possible to adjudge that, the affected phenotype is due to the inversion. Karyotype: 46,XY,add(6)(q21)dn.ish inv(6)(q21q27)(wcp6+). Case 3: PERICENTRIC INVERSION OF CHROMOSOME 12 IN OVODONANT. This inversion does not seem to have an effect on the phenotype, since it is a patient with normal IQ and does not present congenital malformations. Karyotype: 46,XX,inv(12)(p12q14).ish inv(12) (p12q14)(wcp12+). This case report shows the three possible phenotypes of an inversion: pathological, questionable and normal. It is the first report of an inv(13) that confers pathological phenotype. Key words: chromosomal inversion, G Banding, phenotype, structural rearrangement, fluorescence in situ hybridization.

Uranium in drinking water: effects on mouse oocyte quality.

The aim of this work was to evaluate the reproductive toxicological effects of uranium (U) at 2.5, 5, and 10 mgU/kg/d chronically administered in drinking water for 40 d. Swiss female control mice (n = 28) and mice chronically contaminated with uranyl nitrate in drinking water (n = 36) were tested. The number and quality of ovulated oocytes, chromatin organization, and nuclear integrity were evaluated. No significant differences were obtained in the numbers of ovulated oocytes between the different groups. Nevertheless, in 1,520 of the oocytes examined, dysmorphism increased from 11.99% in the control group to 27.99%, 27.19%, and 27.43% in each of the contaminated groups, respectively, in a dose-independent manner. On the other hand, morphological chromatin organization from 880 oocytes examined showed an increase in metaphase plate abnormalities from 37.20% (+/-7.21) in the control group to 55.13% (+/-21.36), 58.29% (+/-21.72), and 64.10% (+/-12.62) in each of the contaminated groups, respectively. Cumulus cell (CC) micronucleation, a parameter of nuclear integrity, increased from 0.21% (+/-0.31) in the control group to 1.92 (+/-0.95), 2.98 (+/-0.97), and 3.2 (+/-0.98), respectively. Both metaphase plate abnormalities and CC micronucleation showed an increase in a dose-dependent manner (r = 0.9; p < 0.001). The oocyte and its microenvironment showed high sensitivity to uranium contamination by drinking water. The lowest observed adverse effect level for this system is estimated at a level below 2.5 mgU/kg/d for female mice.