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Li X.,BGI Shenzhen | Chen S.,BGI Shenzhen | Chen S.,Nanjing Southeast University | Xie W.,BGI Shenzhen | And 14 more authors.
PLoS ONE | Year: 2014

Background: Copy number variations (CNVs) represent an important type of genetic variation that deeply impact phenotypic polymorphisms and human diseases. The advent of high-throughput sequencing technologies provides an opportunity to revolutionize the discovery of CNVs and to explore their relationship with diseases. However, most of the existing methods depend on sequencing depth and show instability with low sequence coverage. In this study, using low coverage whole-genome sequencing (LCS) we have developed an effective population-scale CNV calling (PSCC) method. Methodology/Principal Findings: In our novel method, two-step correction was used to remove biases caused by local GC content and complex genomic characteristics. We chose a binary segmentation method to locate CNV segments and designed combined statistics tests to ensure the stable performance of the false positive control. The simulation data showed that our PSCC method could achieve 99.7%/100% and 98.6%/100% sensitivity and specificity for over 300 kb CNV calling in the condition of LCS (∼2x) and ultra LCS (∼0.2x), respectively. Finally, we applied this novel method to analyze 34 clinical samples with an average of 2x LCS. In the final results, all the 31 pathogenic CNVs identified by aCGH were successfully detected. In addition, the performance comparison revealed that our method had significant advantages over existing methods using ultra LCS. Conclusions/Significance: Our study showed that PSCC can sensitively and reliably detect CNVs using low coverage or even ultra-low coverage data through population-scale sequencing. © 2014 Li et al.


Tan Y.,Central South University | Yin X.,BGI Health | Yin X.,Shenzhen Municipal Birth Defect Screening Project Laboratory | Yin X.,Guangdong Enterprise Key Laboratory of Human Disease Genomics | And 40 more authors.
GigaScience | Year: 2014

Background: Next generation sequencing (NGS) is now being used for detecting chromosomal abnormalities in blastocyst trophectoderm (TE) cells from in vitro fertilized embryos. However, few data are available regarding the clinical outcome, which provides vital reference for further application of the methodology. Here, we present a clinical evaluation of NGS-based preimplantation genetic diagnosis/screening (PGD/PGS) compared with single nucleotide polymorphism (SNP) array-based PGD/PGS as a control.Results: A total of 395 couples participated. They were carriers of either translocation or inversion mutations, or were patients with recurrent miscarriage and/or advanced maternal age. A total of 1,512 blastocysts were biopsied on D5 after fertilization, with 1,058 blastocysts set aside for SNP array testing and 454 blastocysts for NGS testing. In the NGS cycles group, the implantation, clinical pregnancy and miscarriage rates were 52.6% (60/114), 61.3% (49/80) and 14.3% (7/49), respectively. In the SNP array cycles group, the implantation, clinical pregnancy and miscarriage rates were 47.6% (139/292), 56.7% (115/203) and 14.8% (17/115), respectively. The outcome measures of both the NGS and SNP array cycles were the same with insignificant differences. There were 150 blastocysts that underwent both NGS and SNP array analysis, of which seven blastocysts were found with inconsistent signals. All other signals obtained from NGS analysis were confirmed to be accurate by validation with qPCR. The relative copy number of mitochondrial DNA (mtDNA) for each blastocyst that underwent NGS testing was evaluated, and a significant difference was found between the copy number of mtDNA for the euploid and the chromosomally abnormal blastocysts. So far, out of 42 ongoing pregnancies, 24 babies were born in NGS cycles; all of these babies are healthy and free of any developmental problems.Conclusions: This study provides the first evaluation of the clinical outcomes of NGS-based pre-implantation genetic diagnosis/screening, and shows the reliability of this method in a clinical and array-based laboratory setting. NGS provides an accurate approach to detect embryonic imbalanced segmental rearrangements, to avoid the potential risks of false signals from SNP array in this study. © 2014 Tan et al.


Bu J.,Peking University | He S.,University of Chinese Academy of Sciences | Wang L.,Peking University | Li J.,BGI Shenzhen | And 4 more authors.
Indian Journal of Ophthalmology | Year: 2016

Background: Congenital cataract is a rare disorder characterized by crystallin denaturation, which becomes a major cause of childhood blindness. Although more than fifty pathogenic genes for congenital cataract have been reported, the genetic causes of many cataract patients remain unknown. In this study, the aim is to identify the genetic cause of a five-generation Chinese autosomal dominant congenital cataract family. Methods: Whole exome sequencing (WES) was performed on three affected and one unaffected member of the family, known causative genes were scanned first. Sanger sequencing was used to validate co-segregation of the candidate variant in the family. The impact on the transcript and amino acid sequences of the variant was further analyzed. Results: We identified a novel splice donor site mutation c. 2825+1G >A in EPHA2 that was absent in public and in-house databases and showed co-segregation in the family. This variant resulted in an altered splice that led to protein truncation. Conclusions: The mutation we identified was responsible for congenital cataract in our studied family. Our findings broaden the spectrum of causative mutations in EPHA2 gene for congenital cataract and suggest that WES is an efficient strategy to scan variants in known causative genes for genetically heterogeneous diseases. © 2016 Indian Journal of Ophthalmology.


Pan X.,South China University of Technology | Pan X.,Clinical Laboratory of BGI Health | Zhang C.,Clinical Laboratory of BGI Health | Li X.,Clinical Laboratory of BGI Health | And 12 more authors.
Journal of Maternal-Fetal and Neonatal Medicine | Year: 2014

Objective: To develop a fetal sex determination method based on maternal plasma sequencing (MPS), assess its performance and potential use in X-linked disorder counseling. Methods: 900 cases of MPS data from a previous study were reviewed, in which 100 and 800 cases were used as training and validation set, respectively. The percentage of uniquely mapped sequencing reads on Y chromosome was calculated and used to classify male and female cases. Eight pregnant women who are carriers of Duchenne muscular dystrophy (DMD) mutations were recruited, whose plasma were subjected to multiplex sequencing and fetal sex determination analysis. Results: In the training set, a sensitivity of 96% and false positive rate of 0% for male cases detection were reached in our method. The blinded validation results showed 421 in 423 male cases and 374 in 377 female cases were successfully identified, revealing sensitivity and specificity of 99.53% and 99.20% for fetal sex determination, at as early as 12 gestational weeks. Fetal sex for all eight DMD genetic counseling cases were correctly identified, which were confirmed by amniocentesis. Conclusions: Based on MPS, high accuracy of non-invasive fetal sex determination can be achieved. This method can potentially be used for prenatal genetic counseling. © 2014 Informa UK Ltd. All rights reserved.


Pizzino A.,Childrens National Medical Center | Pierson T.M.,Cedars Sinai Medical Center | Guo Y.,Applied Genomics | Helman G.,Childrens National Medical Center | And 19 more authors.
Neurology | Year: 2014

Objective: We present a series of unrelated patients with isolated hypomyelination, with or without mild cerebellar atrophy, and de novo TUBB4A mutations. Methods: Patients in 2 large institutional review board-approved leukodystrophy bioregistries at Children's National Medical Center and Montreal Children's Hospital with similar MRI features had whole-exome sequencing performed. MRIs and clinical information were reviewed. Results: Five patients who presented with hypomyelination without the classic basal ganglia abnormalities were found to have novel TUBB4A mutations through whole-exome sequencing. Clinical and imaging characteristics were reviewed suggesting a spectrum of clinical manifestations. Conclusion: Hypomyelinating leukodystrophies remain a diagnostic challenge with a large percentage of unresolved cases. This finding expands the phenotype of TUBB4A-related hypomyelinating conditions beyond hypomyelination with atrophy of the basal ganglia and cerebellum. TUBB4A mutation screening should be considered in cases of isolated hypomyelination or hypomyelination with nonspecific cerebellar atrophy. © 2014 American Academy of Neurology.

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