Project description:Comparison of multilocus variable number tandem repeat analysis and whole genome sequencing for investigation of Clostridium difficile transmission
Project description:Targeted DNA sequencing approaches will improve how the size of short tandem repeats is measured for diagnostic tests and pre-clinical studies. The expansion of these sequences causes dozens of disorders, with longer tracts generally leading to a more severe disease. In addition, interruptions are sometimes present within repeats and can alter disease manifestation. Despite advances in methodologies, determining repeat size and identifying interruptions in targeted sequencing datasets remains a major challenge. This is because standard alignment tools are ill-suited for the repetitive nature of these sequences. To address this, we have developed Repeat Detector (RD), a deterministic profile weighting algorithm for counting repeats in targeted sequencing data. We tested RD using blood-derived DNA samples from Huntington’s disease (HD) and Fuchs endothelial corneal dystrophy patients sequenced using either Illumina MiSeq or Pacific Biosciences single-molecule, real-time sequencing platforms. RD was highly accurate in determining repeat sizes of 609 HD blood-derived samples and did not require prior knowledge of the flanking sequences or their polymorphisms within the patient population. We demonstrate that RD can be used to identify individuals with repeat interruptions and may provide a measure of repeat instability within an individual. RD is therefore highly versatile and may find applications in the diagnosis of expanded repeat disorders and the development of novel therapies.
Project description:In vertebrates, DNA methylation-mediated repression of retrotransposons is essential for the maintenance of genomic integrity. In the current study, we developed a technique termed HT-TREBS (High-Throughput Targeted Repeat Element Bisulfite Sequencing). This technique is designed to measure the DNA methylation levels of individual loci of any repeat families with next-generation sequencing approaches. To test the feasibility of HT-TREBS, we analyzed the DNA methylation levels of the IAPLTR family using a set of 12 different genomic DNA isolated from the brain, liver and kidney of 4 one-week-old littermates of the mouse strain C57BL/6N. This technique has successfully generated the CpG methylation data of 5,233 loci common in all the samples, representing more than 80% of the individual loci of the five targeted subtypes of the IAPLTR family. According to the results, approximately 5% of the IAPLTR loci have less than 80% average CpG methylation levels with no genomic position preference. Further analyses of the IAPLTR loci also revealed the presence of extensive DNA methylation variations between different tissues and individuals. Overall, these data demonstrate the efficiency and robustness of the new technique, HT-TREBS, and also provide new insights regarding the genome-wide DNA methylation patterns of the IAPLTR repeat elements. High-throughput, single-base resolution, singlicate DNA methylation profiles of IAPLTR retrotransposons in the brain, liver , and kidney of four 1-week-old mouse littemates using the developed technique, HT-TREBS.
Project description:We used a two-component transgene system to study the RNA-dependent DNA methylation (RdDM) and transcriptional gene silencing (TGS) in Arabidopsis. By profiling the small RNA population in mutants defected in RdDM or RNA polymerase II-transcribed trigger for generating silencing siRNA, we investigated how repetitive loci such as tandem repeats were regulated transcriptionally through the action of RNA polymerase IV. Genome-wide small RNA profiling was done by Illumina TruSeq sample preparation followed by high-throughput sequencing with the Illumina HiSeq 2000 platform. The six samples represent mutants and their corresponding control lines.
Project description:Tandem DCIS/IDC are defined as ductal carcicnoma in situ (DCIS) lesions that have concurrent invasive ductal carcinoma (IDC) within the same breast. These are identified radiologically by an area of clustered microcalcifications adjacent to (contiguous with) an invasive mass. Our radiologist (Dr. William P. Smith) has provided us with biopsy cores from each region. One core from each region (DCIS and IDC) has bas been collected and subjected to RNA sequencing for our studies to compare changes from DCIS to IDC in each individual patient. 6 pairs of DCIS-IDC samples were collected, and analysed by RNA sequencing
