RESUMO

Monosomy 21 is an exceedingly rare and fatal chromosomal anomaly. Mosaic monosomy 21, however, can be observed in living patients. There have been discussions on whether there are liveborn cases with true mosaic full monosomy 21. Here, we report the case of a 13-year-old patient with mosaic full monosomy 21 who presented with postnatal microcephaly, low weight, facial dysmorphisms, developmental delay, and severe intellectual disability. To the best of our knowledge, this is the oldest patient with mosaic full monosomy 21 described so far and the first reported in Brazil.

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RESUMO

Down syndrome (DS) is a genetic disorder caused by a trisomy of the human chromosome 21 (Hsa21). Overexpression of Hsa21 genes that encode proteins and non-coding RNAs (ncRNAs) can disrupt several cellular functions and biological processes, especially in the heart. Congenital heart defects (CHDs) are present in 45-50% of individuals with DS. Here, we describe the genetic background of this condition (Hsa21 and non-Hsa21 genes), including the role of ncRNAs, and the relevance of these new players in the study of the pathophysiology of DS heart diseases. Additionally, we discuss several distinct pathways in cardiomyocytes which help maintain a functional heart, but that might trigger hypertrophy and oxidative stress when altered. Moreover, we highlight the importance of investigating how mitochondrial and lysosomal dysfunction could eventually contribute to understanding impaired heart function and development in subjects with the Hsa21 trisomy. Altogether, this review focuses on the newest insights about the gene expression, molecular pathways, and organelle alterations involved in the cardiac phenotype of DS.

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El síndrome de Down es causado por la presencia de una tercera copia del cromosoma 21 y fue descrito por primera vez en 1838 por Jean-Etienne-Dominique, y más tarde por John Langdon Haydon Down en 1866, mientras trabajaba como superintendente médico en el Asilo Real de Earlswood. Desde ese momento, la comunidad científica puso grandes esfuerzos en tratar de elucidar diversos aspectos que influyen en la naturaleza de esta condición, y que determinan su incidencia y factores de riesgo. De igual manera, se ha puesto interés en los genes involucrados en esta enfermedad, la relación genotipo-fenotipo, la expresión del fenotipo, la variabilidad del material genético y las consecuencias transcripcionales que se producen al tener una tercera copia, ya sea parcial o total, del cromosoma 21. Además, se han invertido esfuerzos en identificar biomarcadores y en diseñar metodologías de diagnóstico prenatal no invasivo que sean altamente eficientes para un mejor diagnóstico del síndrome de Down, y así reducir su impacto negativo en las madres gestantes, al proveerlas de información neutral y precisa acerca de vivir con un hijo con síndrome de Down, y darles autonomía en la decisión de la continuación de su embarazo

Down syndrome is caused by the presence of a third copy of chromosome 21 and was first described by Jean-Etienne-Dominique in 1838, and later by John Langdon Haydon Down in 1866, while working as a medical superintendent in the Royal Earlswood Asylum. Since, the scientific community has placed great efforts in trying to elucidate different influencing features in the nature of this condition that determine their incidence and risk factors. In addition, especial attention has been given to the genes involved in this disease, the genotype-phenotype relationship, the expression of the phenotype, the variability of the genetic material and the transcriptional consequences that are produced by having a third copy, either partial or total, of chromosome 21. Additionally, efforts have been invested in identifying biomarkers and designing noninvasive prenatal methodologies that are highly efficient for a better diagnosis of Down syndrome, in order to reduce its negative impact in pregnant mothers, by providing them with neutral and accurate information about life with a child with Down syndrome, as well as providing the autonomy in the decision to continue their pregnancy

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A força muscular respiratória em crianças e adolescentes com Síndrome de Down é comprometida pela hipotonia generalizada que os acometem. Analisar os efeitos da fisioterapia aquática na força muscular respiratória em crianças e adolescentes com síndrome de Down. Estudo de intervenção, quasi-experimental, com amostra constituída de oito crianças e adolescentes diagnosticados com SD e média de idade de 12 anos (± 3,8). Foram realizadas 10 sessões de fisioterapia aquática, com 50 minutos de duração cada, em piscina com água aquecida. A força muscular respiratória foi avaliada a partir da pressão inspiratória máxima (PImáx) e pressão expiratória máxima (PEmáx) com auxílio do manuvacuômetro, sendo obtido seus valores antes do primeiro atendimento e após o último. Analisou-se ainda a saturação periférica de oxigênio e frequência cardíaca. Para comparação das médias antes e depois da intervenção foi utilizado o Teste T pareado. Amostra de indivíduos predominantemente do sexo feminino (75,0%), pardos (75,0%) e residentes em zona urbana (87,5%). A comparação da PImáx e PEmáx antes e após as 10 sessões de fisioterapia aquática evidenciou melhora da força muscular inspiratória e expiratória, sendo tais diferenças estatisticamente significantes (valor de p<0,01). Também foram notadas melhorias na frequência cardíaca e saturação de oxigênio (valor de p<0,05) com a intervenção. Destaca-se neste estudo que a fisioterapia aquática parece ser um recurso terapêutico eficiente para o fortalecimento da musculatura respiratória e melhora dos sinais vitais de crianças e adolescentes de com diagnóstico de Síndrome de Down.

Respiratory muscle strength in children and adolescents with Down syndrome is compromised by the generalized hypotonia that affects them. This study aims to analyze the effects of aquatic physical therapy on respiratory muscle strength in children and adolescents with Down syndrome. Material and method: A quasi-experimental study with a sample consisting of eight children and adolescents diagnosed with DS and mean age of 12 years (± 3.8). Ten sessions of aquatic physiotherapy were performed, each with a duration of 50 minutes, in a pool with heated water. Respiratory muscle strength was assessed from maximal inspiratory pressure (MIP) and maximal expiratory pressure (MEP) using a manuvacuometer, and its values were obtained before the first session and after the last one. Peripheral oxygen saturation and heart rate were also analyzed. The paired T-test was used to compare the means before and after the intervention. Sample of predominantly female (75.0%), brown (75.0%) and urban residents (87.5%). The comparison of MIP and MEP before and after the 10 sessions of aquatic physiotherapy showed an improvement in inspiratory and expiratory muscle strength, and these differences were statistically significant (p <0.01). Improvements in heart rate and oxygen saturation (p value <0.05) were also noted with the intervention. In this study, aquatic physiotherapy seems to be an efficient therapeutic resource for the strengthening of respiratory muscles and improvement of the vital signs of children and adolescents diagnosed with Down's Syndrome.

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Objetivo: Avaliar a eficácia da estimulação cortical no desenvolvimento perceptivo motor de adolescentes com Síndrome de Down (SD). Métodos: Realizou-se um estudo experimental, com 36 adolescentes com idade compreendida entre 13 a 17 anos de idade, estudantes da Associação de Pais e Amigos dos Excepcionais, divididos em grupo controle (GA) e grupo experimental (GB). Foram avaliados pelo teste de processamento mental e como procedimento de intervenção utilizou-se o programa de estimulação cortical que foi realizado através de estímulos auditivos por vias de batidas. Resultados: Obteve-se para GBXGA um valor significativo entre os blocos F= 21.08 um p <0.01, portanto o melhor desempenho dos participantes do GB, não foi ao acaso, pois para dirimir qualquer dúvida aplicou-se o teste de Turkey, que revelou para uma variância Q= 0.08 um p<0.01. Conclusão: Dessa forma a presente pesquisa constatou a eficácia que a estimulação cortical proporcionou na melhora significativa no desenvolvimento perceptivo motor dos adolescentes com SD.

Objective: To evaluate the efficacy of cortical stimulation in the motor perceptive development of adolescents with Down syndrome (DS). Methods: An experimental study was carried out with 36 adolescents between the ages of 13 and 17, students of the Association of Parents and Friends of the Exceptional, divided into control group (GA) and experimental group (GB). They were evaluated by the mental processing test and as an intervention procedure the cortical stimulation program was performed through auditory stimuli by beat pathways. Results: A significant value was found for GBXGA between the F= 21.08 and p<0.01 blocks, so the best performance of the participants in GB was not random, since the Turkey test was used to resolve any doubts. Revealed for a variance Q= 0.08 a p <0.01. Conclusion: In this way the present research verified the effectiveness that the cortical stimulation provided in the significant improvement in the motor perceptive development of the adolescents with DS.

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BACKGROUND: An intrachromosomal amplification of chromosome 21 (iAMP21) defines a unique subgroup of B-cell precursor acute lymphoblastic leukemia (BCP-ALL). The finding of three or more extra copies of the RUNX1 gene by fluorescence in situ hybridization (FISH) is internationally used to define an iAMP21. Genomic profiling of chromosome 21 has been suggested for assisting diagnostic case identification. Due to limitations of comparative genomic hybridization, in terms of a routine application as first line-screening tests we evaluated the multiplex ligation-dependent probe amplification (MLPA) SALSA P327_A1 and P327_B1 probe sets for detecting chromosome 21 copy number alterations in Brazilian childhood BCP-ALL. RESULTS: In 74 out of 368 patients gain of genetic material was detected. For data confirmation RUNX1 directed FISH was performed. Cells with ≥5 RUNX1 signals (n = 9) were considered as "true iAMP21" while <5 RUNX1 signals (n = 41) were counted as evidence for additional copies of intact chromosomes 21. All patients with an iAMP21 had high MLPA peak ratios (≥1.8), while the majority of patients with <5 RUNX1 presented low MLPA peak ratios (<1.8). Observed differences gained statistical strength by comparing probes located within the common region of amplification. Next, a principal component analysis was performed in order to illustrate distribution of cases according to their MLPA peak profile in two dimensions. Cases with an iAMP21 mostly clustered together, however additional cases with <5 RUNX1 signals or no available FISH data located in proximity. CONCLUSIONS: MLPA qualified as a high throughput technique that could be employed in future studies for a critical comparison with data obtained by FISH, especially in cases where metaphase nuclei are not available. Taking submicroscopic aberrations into account examined by MLPA, cases exhibiting an "iAMP21 like" peak ratio profile but <5 RUNX1 signals should be considered as candidates for this chromosomal abnormality.

RESUMO

Las inversiones pericéntricas están entre los reordenamientos cromosómicos balanceados más usuales, con una frecuencia de un 1-2 %. Al laboratorio de citogenética del Centro Nacional de Genética Médica se remite una paciente con múltiples abortos del primer trimestre del embarazo. Se realizó el cariotipo en sangre periférica a una resolución de 450 bandas. La paciente presentó una inusual inversión pericéntrica del cromosoma 21 con la fórmula cromosómica 46,XX,inv (21) (p11.2 q21.1). Se discuten los posibles gametos resultantes de la segregación meiótica en esta paciente y se valoran los riesgos de abortos e hijos malformados teniendo en cuenta los puntos de ruptura en el 21.

Pericentric inversions are among the most frequent chromosomal rearrangements with a frequency of 1-2 %. A woman with repeated first trimester pregnancy loss was referred to cytogenetic laboratory of The National Center of Human Genetics. A karyotype conventional banding technique at resolution of ~450 was made. The patient presented an unusual pericentric inversion 46,XX,inv (21)(p11.2 q21.1). The possible gametes as result of crossover events (during the pachytene stage of meiosis I) were discussed. The risk of miscarriages and malformed children were evaluated according the breakpoint in 21 chromosome.

RESUMO

En Costa Rica, el diagnóstico de anomalías cromosómicas fetales se realiza solo mediante el análisis citogenético convencional de cromosomas obtenidos de cultivos celulares. Además de que la espera por los resultados puede ser larga, con alguna frecuencia fracasa el cultivo, por contaminación o por mala calidad de la muestra, o las figuras mitóticas no se pueden analizar, por lo que es necesario disponer de una metodología sencilla y barata, para obtener un diagnóstico prenatal rápido y fiable de trisomía 21, 18 ó 13, en embarazos de alto riesgo genético sometidos a amniocentesis o cordocentesis. Métodos: Se diseñaron tres PCRs multiplex para amplificar cuatro distintas repeticiones cortas en tándem, de cada uno de los cromosomas 21, 18 y 13. Se colectaron 93 muestras (88 líquidos amnióticos y 5 sangres fetales), recibidas en el laboratorio entre 2006 y 2008, con solicitud de análisis cromosómico. Los resultados de la reacción en cadena de la polimerasa cuantitativa fluorescente, fueron comparados con el cariotipo obtenido de las mismas muestras para demostrar la fiabilidad del ensayo. Resultados: Para este grupo de datos, la exactitud del ensayo fue del 100 por ciento y se consiguió obtener resultados en 48 horas. Se logró realizar el análisis de repeticiones cortas en tándem en el 77 por ciento de las muestras en las que no se pudo obtener crecimiento celular. Conclusión: La reacción en cadena de la polimerasa cuantitativa fluorescente demostró ser una metodología sencilla, fiable y rápida, por lo que podría convertirse en una herramienta complementaria del análisis cromosómico convencional. La obtención de resultados rápidos en casos de diagnóstico prenatal podría disminuir el periodo de ansiedad parental por la espera de los resultados, así como permitir un mejor abordaje terapéutico de los fetos afectados.

In Costa Rica, the diagnosis of chromosomal fetal anomalies is realizedonly by conventional cytogenetic analysis of chromosomes obtained from cellular cultures. The waiting for the results can be long. Moreover with some frequency culture fails due tocontamination or bad quality of the sample or they cannot be analyzed. This makes it necessary to have a simple and cheap methodology to obtain an accurate and rapid fetal diagnosis of trisomy 21, 18 or 13, in pregnancies of high genetic risk submitted to amniocentesis or cordocentesis. Materials and methods: Three multiplex PCRs were designed to amplify four different short tandem repeats of each of the chromosomes 21, 18 and 13. There were collected 93 samples (88amniotic fluids and 5 fetal bloods), received in the laboratory between 2006 and 2008 with request ofor chromosomal analysis. The results of the quantitative fluorescent PCR werecompared with the obtained cariotype of the same samples to stablish the accuracy demonstrate the reliability of the assay. Results: Accuracy of the assay was 100% and it was possible to obtain results within 48 hours.STRs analysis could be made in 77% of the samples where the cellular culture could not be done. Conclusion: The quantitative fluorescent PCR demonstrated to be a simple, accurate and rapid methodology, from what it might turn into a complementary tool of the chromosomal conventional analysis. The securing of rapid results in cases of antenatal diagnosis might diminish the period of anxiety parental for the waiting of the results, as well as to allow a better therapeutic management of the affected fetuses.

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