Objectives To validate the clinical efficacy and practical feasibility of massively parallel maternal plasma DNA sequencing to screen for fetal trisomy 21 among high risk pregnancies clinically indicated for amniocentesis or chorionic villus sampling. Design Diagnostic accuracy validated against full karyotyping, using prospectively collected or archived maternal plasma samples. Setting Prenatal diagnostic units in Hong Kong, United Kingdom, and the Netherlands. Participants 753 pregnant women at high risk for fetal trisomy 21 who underwent definitive diagnosis by full karyotyping, of whom 86 had a fetus with trisomy 21. Intervention Multiplexed massively parallel sequencing of DNA molecules in maternal plasma according to two protocols with different levels of sample throughput: 2-plex and 8-plex sequencing. Main outcome measures Proportion of DNA molecules that originated from chromosome 21. A trisomy 21 fetus was diagnosed when the z score for the proportion of chromosome 21 DNA molecules was >3. Diagnostic sensitivity, specificity, positive predictive value, and negative predictive value were calculated for trisomy 21 detection. Results Results were available from 753 pregnancies with the 8-plex sequencing protocol and from 314 pregnancies with the 2-plex protocol. The performance of the 2-plex protocol was superior to that of the 8-plex protocol. With the 2-plex protocol, trisomy 21 fetuses were detected at 100% sensitivity and 97.9% specificity, which resulted in a positive predictive value of 96.6% and negative predictive value of 100%. The 8-plex protocol detected 79.1% of the trisomy 21 fetuses and 98.9% specificity, giving a positive predictive value of 91.9% and negative predictive value of 96.9%. ConclusionMultiplexed maternal plasma DNA sequencing analysis could be used to rule out fetal trisomy 21 among high risk pregnancies. If referrals for amniocentesis or chorionic villus sampling were based on the sequencing test results, about 98% of the invasive diagnostic procedures could be avoided.

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.

RÉSUMÉL'objectif de cette étude était d'évaluer la facilité d'utilisation d'un nouveau service de soutien pour personnel soignant basé sur Internet (ICSS) et d'évaluer ses effets sur la santé des Canadiens chinois qui ont soigné un membre de la famille atteinte de démence. Les données démogaphiques et de questionnaire ont été recueillies auprès de 28 participants, et des entrevues approfondies ont été realisées avec 10 participants. Les résultats ont démontré que ceux qui n'ont pas participé à ICSS ont revelé plus hauts niveaux de charge après l'intervention, lors que les participants fréquents a montré une réduction en charge après l'intervention. Les croyances traditionelles ont formées les besoins des soignants; de plus, les contextes ethnoculturelle-linquistiques ont touchées la facilité d'utilisation et ont été associées au comportement pendant l'utilisation. De même, l'utilisation d'ICSS a été infl uencée par la compétence informatique et par préferences linguistiques. Cette étude indique que les soignants peuvent bénéfi cier du soutien professionnel par e-mails asynchrones et un site Web dedié d'informations. L'ICSS est une approche possible pour soutenir les soignants qui préferent un modèle de service alternative. Ce service emergent nécessite plus de la recherche sur: la conception technologique amélioré, les modèles de prestation de services pour les immigrants soignants et l'évaluation de l'effi cacité et rentabilité. ABSTRACTThe aim of this study was to assess the usability of a new Internet-based Caregiver Support Service (ICSS) and evaluate its effects on health outcomes of Chinese Canadians who cared for a family member with dementia. Demographic and questionnaire data were collected from 28 participants, and in-depth interviews were conducted with 10 participants. Results showed that non-users reported higher levels of burden post-intervetion, and frequent users showed postintervention reduction in experienced burden. Traditional beliefs shaped caregivers' needs; also, ethno-cultural-linguistic contexts affected system usability and were associated with usage behaviour. This study indicates that caregivers can benefi t from receiving professional support via asynchronous e-mails and a dedicated information web site. The ICSS is a feasible approach for supporting caregivers who prefer an alternative service model. This emerging service requires more research in: enhanced technology design, service delivery models for immigrant caregivers, and evaluation of effectiveness and cost-effectiveness.