1,720,974 research outputs found
Focal cortical dysplasia, microcephaly and epilepsy in a boy with 1q21.1-q21.3 duplication
No full textThe recent advance of new molecular technologies like array - Comparative Genomic Hybridization has fostered the detection of genomic imbalances in subjects with intellectual disability, epilepsy, and/or congenital anomalies. Though some of the rearrangements are relatively frequent, their consequences on phenotypes can be strongly variable. We report on a boy harbouring a de novo 8.3 Mb duplication of chromosome 1q21.1-q21.3 whose complex unusual phenotype deserves attention, due to the presence of focal cortical dysplasia, microcephaly, and epilepsy. Loss-of-function (LOF) effects of genes associated with human disease involved in the rearrangement have been only partially established, and have not been previously associated with brain malformations in several deletion syndromes. Less is known, instead, about the consequences of their duplication on neuronal migration and brain development process. Further advance in neuroimaging and genetic research will help in defining their actual role in neurodevelopment and cerebral cortex malformations
The prognostic role of chromosomal gains and loss in sporadic medullary thyroid carcinoma
No full textBackground: Human cancer is characterized by the accumulation of somatic alterations including base substitutions, indels, structural rearrangements and somatic copy number alteration (CNA), either gain or loss, of chromosomes that can be responsible either for initiation and/or cancer progression. About 80% of Sporadic Medullary Thyroid Carcinoma (sMTC) harbor RET or RAS somatic alterations with a negative prognostic role for the presence of the RET mutation; a few studies about the role of chromosomal CNA in MTC have been published so far showing a variable frequency ranging from 50%-77%.
Objective: Aim of this study was to evaluate the global genomic profile of a series of 41 sMTC obtained by Comparative Genomic Hybridization array (array-CGH). The presence of CNAs was compared to the presence of a RET mutation and clinical and pathological features of MTC patients in order to investigate their role in tumor behaviour.
Methods and Results: Twenty-five cases (25/41, 61%) showed at least one CNA with a range of CNA per sample: [1 to 27] while 16 cases (16/41, 39%) did not show any CNA. In general, losses in chromosomal regions were more frequent than gains (91 vs 50 events). Chromosomes most frequently involved in CNA were chromosome 22 (31.7% of cases), chromosome 1 (29.3% of cases), chromosomes 3 (19.5% of cases), chromosomes 10 (17.1% of cases), chromosome 21 (14.6% of cases), while the remaining chromosomes were affected only by few CNAs. When we compared the presence of CNA with the presence of somatic RET mutations, we found that 18/23 RET+ cases (78.3%), showed the presence of at least one CNA, present in only 7/18 (38.9%) RET- cases (P = 0.02). The CNAs in RET+ MTC patients were significantly associated with chromosomes 3 (P = 0.0035) and 10 (P = 0.007). We finally correlated the cases harboring at least one CNA with the outcome of sMTC patients (disease free, persistent disease at biochemical level and metastatic disease) and we found that patients present in a metastatic disease showed a higher rate of CNAs (P = 0.005) and the chromosomes mainly affected by these CNAs were chromosomes 3 (P = 0.002), 9 (P = 0.02), 10 (P = 0.2) and 16 (P = 0.02).
Conclusions: In conclusion, MTC cases showing CNAs were mainly the ones harboring a RET mutation, suggesting that a higher level of chromosomal instability could be responsible for a higher rate of chromosomal alterations. Interestingly, the regions involved with loss and gain show the presence of important tumor suppressor genes and oncogenes, respectively, that could justify a role of these CNAs in the progression of the disease
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Deletion Extents Are Not the Cause of Clinical Variability in 22q11.2 Deletion Syndrome: Does the Interaction between DGCR8 and miRNA-CNVs Play a Major Role?
Full text linkIn humans, the most common genomic disorder is the hemizygous deletion of the chromosome 22q11.2 region, that results in the “22q11.2 deletion syndrome” (22q11.2DS). A peculiarity of 22q11.2DS is its great phenotypic variability that makes this pathology a classic example of a syndrome with variable expressivity and incomplete penetrance. The reasons for this variability have not been elucidated yet, and the molecular substrates underlying the different clinical features of 22q11.2DS are still debated. A cohort of 21 patients has been analyzed by array CGH in order to detect some of the genetic differences that may influence this variability. Two aspects have been investigated: (1) the precise localization of the deletion breakpoints within the low copy repeats (LCRs), (2) the additional Copy Number Variations (CNVs) elsewhere in the genome, by analyzing their gene content. Both protein-coding genes and miRNAs were considered, in order to discover possible epistatic interactions between genes of the 22q11.2 region and the rest of the genome. Eighteen out of twenty-one patients had a deletion of ~3 Mb mediated by LCR22-A and D, whereas 3/21 had a smaller deletion. The breakpoints within the LCR22-A and D do not have a major role in the phenotypic variability since they are rather clustered and the small differences concern genes that are not directly related to clinical signs of 22q11.2DS. A detailed analysis of the gene content of 22q11.2 deleted region indicates that this syndrome could be a bioenergetic disorder or consequence of an altered post-transcriptional gene regulation, due to the presence of DGCR8, a major player of the microRNA (miRNA) biogenesis. Only four genes with mitochondrial function are harbored in the additional CNVs, whereas 11 miRNA, all related to biological pathways present in the 22q11.2DS, have been detected in 19/21 patients. CNVs and miRNAs are new entities that have changed the order of complexity at the level of gene expression and regulation, thus CNV-miRNAs (miRNA harbored in the CNVs) are potential functional variants that should be considered high priority candidate variants in genotype-phenotype association studies. Deletion of DGCR8, the main actor in miRNA biogenesis, amplifies this variability. To our knowledge, this is the first report that focus on the miRNA-CNVs in 22q11.2DS, with the aim of trying to better understand their role in the variable expressivity and incomplete penetrance
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
625 kb microduplication at Xp22.12 including RPS6KA3 in a child with mild intellectual disability
No full textHere, we report on a patient with a 625 kb duplication in Xp22.12, detected by array comparative genomic hybridization (CGH). The duplicated region contains only one gene, RPS6KA3, that results in partial duplication. The same duplication was present in his mother and his maternal uncle. This partial duplication inhibits the RPS6KA3 expression, mimicking the effect of loss-of-function mutations associated with Coffin-Lowry syndrome (CLS). The phenotype of the patient here presented is not fully evocative of this syndrome because he does not present some of the facial, digital and skeletal abnormalities that are considered the main diagnostic features of CLS. This case is one of the few examples where RPS6KA3 mutations are associated with a non-specific X-linked mental retardation.Journal of Human Genetics advance online publication, 10 September 2015; doi:10.1038/jhg.2015.106
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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