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Background
The putative promoter of the holocarboxylase synthetase (HLCS) gene on chromosome 21 is hypermethylated in placental tissues and could be detected as a fetal-specific DNA marker in maternal plasma. Detection of fetal trisomy 21 (T21) has been demonstrated by an epigenetic-genetic chromosome dosage approach where the amount of hypermethylated HLCS in maternal plasma is normalized using a fetal genetic marker on the Y chromosome as a chromosome dosage reference marker. We explore if this method can be applied on both male and female fetuses with the use of a paternally-inherited fetal single nucleotide polymorphism (SNP) allele on a reference chromosome for chromosome dosage normalization.Methodology
We quantified hypermethylated HLCS molecules using methylation-sensitive restriction endonuclease digestion followed by real-time or digital PCR analyses. For chromosome dosage analysis, we compared the amount of digestion-resistant HLCS to that of a SNP allele (rs6636, a C/G SNP) that the fetus has inherited from the father but absent in the pregnant mother.Principal Findings
Using a fetal-specific SNP allele on a reference chromosome, we analyzed 20 euploid and nine T21 placental tissue samples. All samples with the fetal-specific C allele were correctly classified. One sample from each of the euploid and T21 groups were misclassified when the fetal-specific G allele was used as the reference marker. We then analyzed 33 euploid and 14 T21 maternal plasma samples. All but one sample from each of the euploid and T21 groups were correctly classified using the fetal-specific C allele, while correct classification was achieved for all samples using the fetal-specific G allele as the reference marker.Conclusions
As a proof-of-concept study, we have demonstrated that the epigenetic-genetic chromosome dosage approach can be applied to the prenatal diagnosis of trisomy 21 for both male and female fetuses. 相似文献4.
Lo YM Tsui NB Chiu RW Lau TK Leung TN Heung MM Gerovassili A Jin Y Nicolaides KH Cantor CR Ding C 《Nature medicine》2007,13(2):218-223
Current methods for prenatal diagnosis of chromosomal aneuploidies involve the invasive sampling of fetal materials using procedures such as amniocentesis or chorionic villus sampling and constitute a finite risk to the fetus. Here, we outline a strategy for fetal chromosome dosage assessment that can be performed noninvasively through analysis of placental expressed mRNA in maternal plasma. We achieved noninvasive prenatal diagnosis of fetal trisomy 21 by determining the ratio between alleles of a single-nucleotide polymorphism (SNP) in PLAC4 mRNA, which is transcribed from chromosome 21 and expressed by the placenta, in maternal plasma. PLAC4 mRNA in maternal plasma was fetal derived and cleared after delivery. The allelic ratios in maternal plasma correlated with those in the placenta. Fetal trisomy 21 was detected noninvasively in 90% of cases and excluded in 96.5% of controls. 相似文献
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Chen EZ Chiu RW Sun H Akolekar R Chan KC Leung TY Jiang P Zheng YW Lun FM Chan LY Jin Y Go AT Lau ET To WW Leung WC Tang RY Au-Yeung SK Lam H Kung YY Zhang X van Vugt JM Minekawa R Tang MH Wang J Oudejans CB Lau TK Nicolaides KH Lo YM 《PloS one》2011,6(7):e21791
Massively parallel sequencing of DNA molecules in the plasma of pregnant women has been shown to allow accurate and noninvasive prenatal detection of fetal trisomy 21. However, whether the sequencing approach is as accurate for the noninvasive prenatal diagnosis of trisomy 13 and 18 is unclear due to the lack of data from a large sample set. We studied 392 pregnancies, among which 25 involved a trisomy 13 fetus and 37 involved a trisomy 18 fetus, by massively parallel sequencing. By using our previously reported standard z-score approach, we demonstrated that this approach could identify 36.0% and 73.0% of trisomy 13 and 18 at specificities of 92.4% and 97.2%, respectively. We aimed to improve the detection of trisomy 13 and 18 by using a non-repeat-masked reference human genome instead of a repeat-masked one to increase the number of aligned sequence reads for each sample. We then applied a bioinformatics approach to correct GC content bias in the sequencing data. With these measures, we detected all (25 out of 25) trisomy 13 fetuses at a specificity of 98.9% (261 out of 264 non-trisomy 13 cases), and 91.9% (34 out of 37) of the trisomy 18 fetuses at 98.0% specificity (247 out of 252 non-trisomy 18 cases). These data indicate that with appropriate bioinformatics analysis, noninvasive prenatal diagnosis of trisomy 13 and trisomy 18 by maternal plasma DNA sequencing is achievable. 相似文献
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Background
Participant reports of their own behaviour are critical for the provision and evaluation of behavioural interventions. Recent developments in brief alcohol intervention trials provide an opportunity to evaluate longstanding concerns that answering questions on behaviour as part of research assessments may inadvertently influence it and produce bias. The study objective was to evaluate the size and nature of effects observed in randomized manipulations of the effects of answering questions on drinking behaviour in brief intervention trials.Methodology/Principal Findings
Multiple methods were used to identify primary studies. Between-group differences in total weekly alcohol consumption, quantity per drinking day and AUDIT scores were evaluated in random effects meta-analyses.Ten trials were included in this review, of which two did not provide findings for quantitative study, in which three outcomes were evaluated. Between-group differences were of the magnitude of 13.7 (−0.17 to 27.6) grams of alcohol per week (approximately 1.5 U.K. units or 1 standard U.S. drink) and 1 point (0.1 to 1.9) in AUDIT score. There was no difference in quantity per drinking day.Conclusions/Significance
Answering questions on drinking in brief intervention trials appears to alter subsequent self-reported behaviour. This potentially generates bias by exposing non-intervention control groups to an integral component of the intervention. The effects of brief alcohol interventions may thus have been consistently under-estimated. These findings are relevant to evaluations of any interventions to alter behaviours which involve participant self-report. 相似文献9.
Mohammad Shakhawat Hossain Kypros Kypri Bayzidur Rahman Iqbal Arslan Shahnaz Akter Abul Hasnat Milton 《PloS one》2014,9(1)
Objective
To estimate the prevalence and identify correlates of smokeless tobacco consumption among married rural women with a history of at least one pregnancy in Madaripur, Bangladesh.Materials and Methods
We conducted a cross-sectional survey using an interviewer administered, pre-tested, semi-structured questionnaire. All women living in the study area, aged 18 years and above with at least one pregnancy in their lifetime, who were on the electoral roll and agreed to participate were included in the study. Information on socio-demographic characteristics and smokeless tobacco consumption was collected. Smokeless tobacco consumption was categorized as ‘Current’, ‘Ever but not current’ and ‘Never’. Associations between smokeless tobacco consumption and the explanatory variables were estimated using simple and multiple binary logistic regression.Results
8074 women participated (response rate 99.9%). The prevalence of ‘Current consumption’, ‘Ever consumption but not current’, and ‘Never consumption’ was 25%, 44% and 31%, respectively. The mean age at first use was 31.5 years. 87% of current consumers reported using either Shadapata or Hakimpuree Jarda. Current consumption was associated with age, level of education, religion, occupation, being an income earner, marital status, and age at first use of smokeless tobacco. After adjustment for demographic variables, current consumption was associated with being over 25 years of age, a lower level of education, being an income earner, being Muslim, and being divorced, separated or widowed.Conclusion
The prevalence of smokeless tobacco consumption is high among rural women in Bangladesh and the age of onset is considerably older than that for smoking. Smokeless tobacco consumption is likely to be producing a considerable burden of non-communicable disease in Bangladesh. Smokeless tobacco control strategies should be implemented. 相似文献10.
Anna L. David Andrew Holloway Louise Thomasson Argyro Syngelaki Kypros Nicolaides Roshni R. Patel Brian Sommerlad Amie Wilson William Martin Lyn S. Chitty 《PloS one》2014,9(10)