Identification of a mosaic non-inherited small supernumerary ring chromosome 2: cytogenetic-molecular studies and genotype-phenotype correlation

Introduction: The identification of supernumerary marker chromosomes (SMCs) derived from all the autosomes is currently possible, but rarely by conventional cytogenetics alone. Supernumerary ring chromosomes (SRCs) account for about 10% of these cases. SRCs derived from chromosome 2 are unusual, and there are only a few cases reported in the literature. The severity of the phenotype depends on the type of the mosaicism, the percentage of cells affected by the genetic change and the chromosome involved. Methods: The authors report the case of a boy aged 8 referred for cytogenetic studies, presenting with behavior and learning problems, mental retardation with uncoordenated speech, attention deficit and hyperactivity (PHDA), as well as small slanting palpebral fissures. The karyotype was obtained from peripheral blood lymphocyte cultures using high resolution GTL banding and standard techniques. Fluorescence in situ hybridization (FISH) was performed using specific probes for the centromeric regions of all chromosomes (Chromoprobe Multiprobe - ISystem). Results: Cytogenetic analysis revealed two cell lines: one with a supernumerary marker ring chromosome, 47,XY,+r (52%), and a normal cell line, 46,XY (48%). The SRC was identified by FISH with the chromosome 2 centromeric probe. Since the parents had normal karyotypes, this abnormality was “de novo”. Final karyotype of the proband was: mos 47,XY,+r[26]/46,XY[24].ish r(2)(D2Z2+)dn. Discussion: The clinical description of this patient is in agreement with other reports of the literature. Molecular characterization by FISH analyses is an useful way of investigating the presence of euchromatin contained in a SMC and establishing new chromosomal syndromes. However, to better characterize this ring, in order to establish a more accurate genotype-phenotype correlation, more studies involving other technologies should be performed, thus allowing suitable genetic counsellin

Deleção cromossómica intersticial em 14q “de novo”: apresentação de um caso

Introdução: As deleções intersticiais são anomalias cromossómicas estruturais, desequilibradas, resultantes de dois pontos de quebra, frequentemente associadas a quadros clínicos anormais devido à perda de material genético ativo (eucromatina). As consequências fenotípicas dependem do segmento cromossómico perdido e do número de genes aí localizados. Material e Métodos: Os autores apresentam o caso de um indivíduo do sexo masculino, de 11 anos de idade, referenciado para estudo citogenético por apresentar um quadro clínico de atraso de desenvolvimento psicomotor, défice cognitivo e problemas de comportamento. Realizaram-se culturas sincronizadas de linfócitos de sangue periférico, bandas GTG de alta resolução e, posteriormente, estudos de hibridação in situ por fluorescência (FISH) com sondas de pintura cromossómica total e subtelomérica, específicas para o cromossoma 14. Resultados: A análise das metafases revelou a presença de uma anomalia estrutural no cromossoma 14, interpretada como uma deleção intersticial do segmento compreendido entre as bandas 14q24.3 e 14q32.1. A análise por FISH permitiu confirmar esta deleção intersticial. Como os cariótipos dos pais foram normais, conclui-se que esta anomalia cromossómica é “de novo”, estabelecendo-se o cariótipo do doente como: 46,XY,del(14)(q24.3q32.1).ish del(14)(wcp 14+,SHGC36156+)dn Discussão: A deleção intersticial encontrada no cromossoma 14 implica uma monossomia do segmento 14q24.3→14q32.1. As alterações descritas mais comuns, associadas a esta deleção, incluem ADPM e algumas malformações minor. Os autores apresentam este caso pela raridade da anomalia citogenética encontrada e comparam-no com a literatura atual

Interstitial deletion 15q21 and Prader-Willi like syndrome phenotype: Case report

Introduction: Chromosome 15q interstitial deletions not involving the Prader-Willi/Angelman region are uncommon and poorly characterized. Very few cases of different segmental losses involving the 15q21 region have been reported at cytogenetic level. All the described patients present with moderate to several mental retardation and characteristic facial dysmorphic features. Some authors compare the similarity between the phenotype of these patients with some features of Prader-Willi syndrome (PWS). Methods: We report the case of a girl aged 8 referred for conventional cytogenetics and fluorescence in situ hybridization (FISH) for the PWS region, presenting with mental retardation, almond-shaped eyes, obesity, small hands with short fingers and diminished pigmentation of the hair. Results: The chromosomal analysis revealed an interstitial deletion of the long arm of chromosome 15, apparently between 15q21 and 15q22. Deletion at 15q11.2 (Prader-Willi/Angelman critical region) was excluded by FISH. To establish the exact breakpoints molecular studies were performed using bacterial artificial chromosome (BAC) clones spanning the 15q21.3 region. The absence of signal in this region defines the proband’s final karyotype as: 46,XX,del(15)(q21.3q21.3).ish del(15)(q21.3q21.3)(bA74K1-) Discussion: The authors emphasize the importance of complementary FISH and molecular studies in chromosomal abnormalities and compare the proband’s phenotype with similar cases described in the literature

Diagnóstico Citogenético em Líquidos Amnióticos Realizado entre 2000-2011 no Centro de Genética Médica Jacinto Magalhães, INSA, IP

Introdução: O diagnóstico pré-natal citogenético efetuado em líquido amniótico é um método seguro e fiável para deteção de anomalias cromossómicas fetais, sendo habitualmente realizado a partir das 15 semanas de gestação. Obtêm-se resultados, em média, após 8-10 dias de cultura dos amniócitos. Objectivo: Apresentar a estatística dos resultados obtidos na análise citogenética de líquidos amnióticos realizada na Unidade de Citogenética do Centro de Genética Médica Jacinto Magalhães entre 2000 e 2011, comparando-os com o descrito na literatura. Material e métodos: Entre janeiro de 2000 e dezembro de 2011 foram processados 10149 líquidos amnióticos. Os motivos para a realização da amniocentese foram, nomeadamente, idade materna avançada, anomalias ecográficas, marcadores ecográficos, rastreio bioquímico positivo, familiares com anomalias cromossómicas e risco de doença monogénica. Foram realizadas culturas de amniócitos de acordo com as técnicas convencionais de citogenética e os cromossomas identificados com bandas GTG ou GTL. Sempre que necessário efetuaram-se estudos de citogenética molecular (FISH) com as sondas adequadas ao esclarecimento do caso. Resultados: A análise revelou 342 cariótipos anormais (3,4%) dos quais 234 tinham anomalias numéricas e 108 estruturais. Os Síndromes de Down, de Edwards e de Turner foram as anomalias mais frequentes. Vinte e três culturas não cresceram, representando uma percentagem de 0,2% de insucesso. Conclusões: Os autores correlacionam os resultados obtidos com as indicações clínicas fornecidas e comparam-nas com o descrito na literatura. O presente estudo poderá ser utilizado para o estabelecimento de uma base de dados a nível nacional

Jet size dependence of single jet suppression in lead-lead collisions at sqrt(s(NN)) = 2.76 TeV with the ATLAS detector at the LHC

Measurements of inclusive jet suppression in heavy ion collisions at the LHC provide direct sensitivity to the physics of jet quenching. In a sample of lead-lead collisions at sqrt(s) = 2.76 TeV corresponding to an integrated luminosity of approximately 7 inverse microbarns, ATLAS has measured jets with a calorimeter over the pseudorapidity interval |eta| < 2.1 and over the transverse momentum range 38 < pT < 210 GeV. Jets were reconstructed using the anti-kt algorithm with values for the distance parameter that determines the nominal jet radius of R = 0.2, 0.3, 0.4 and 0.5. The centrality dependence of the jet yield is characterized by the jet "central-to-peripheral ratio," Rcp. Jet production is found to be suppressed by approximately a factor of two in the 10% most central collisions relative to peripheral collisions. Rcp varies smoothly with centrality as characterized by the number of participating nucleons. The observed suppression is only weakly dependent on jet radius and transverse momentum. These results provide the first direct measurement of inclusive jet suppression in heavy ion collisions and complement previous measurements of dijet transverse energy imbalance at the LHC.Comment: 15 pages plus author list (30 pages total), 8 figures, 2 tables, submitted to Physics Letters B. All figures including auxiliary figures are available at http://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/HION-2011-02

Search for direct production of charginos and neutralinos in events with three leptons and missing transverse momentum in √s = 7 TeV pp collisions with the ATLAS detector

A search for the direct production of charginos and neutralinos in final states with three electrons or muons and missing transverse momentum is presented. The analysis is based on 4.7 fb−1 of proton–proton collision data delivered by the Large Hadron Collider and recorded with the ATLAS detector. Observations are consistent with Standard Model expectations in three signal regions that are either depleted or enriched in Z-boson decays. Upper limits at 95% confidence level are set in R-parity conserving phenomenological minimal supersymmetric models and in simplified models, significantly extending previous results

Measurement of the inclusive isolated prompt photon cross-section in pp collisions at sqrt(s)= 7 TeV using 35 pb-1 of ATLAS data

A measurement of the differential cross-section for the inclusive production of isolated prompt photons in pp collisions at a center-of-mass energy sqrt(s) = 7 TeV is presented. The measurement covers the pseudorapidity ranges |eta|<1.37 and 1.52<=|eta|<2.37 in the transverse energy range 45<=E_T<400GeV. The results are based on an integrated luminosity of 35 pb-1, collected with the ATLAS detector at the LHC. The yields of the signal photons are measured using a data-driven technique, based on the observed distribution of the hadronic energy in a narrow cone around the photon candidate and the photon selection criteria. The results are compared with next-to-leading order perturbative QCD calculations and found to be in good agreement over four orders of magnitude in cross-section.Comment: 7 pages plus author list (18 pages total), 2 figures, 4 tables, final version published in Physics Letters