Whole Genome Methylation Analysis of Nondysplastic Barrett Esophagus that Progresses to Invasive Cancer.

OBJECTIVE: To investigate differences in methylation between patients with nondysplastic Barrett esophagus who progress to invasive adenocarcinoma and those who do not. BACKGROUND: Identifying patients with nondysplastic Barrett esophagus who progress to invasive adenocarcinoma remains a challenge. Previous studies have demonstrated the potential utility of epigenetic markers for identifying this group. METHODS: A whole genome methylation interrogation using the Illumina HumanMethylation 450 array of patients with nondysplastic Barrett esophagus who either develop adenocarcinoma or remain static, with validation of findings by bisulfite pyrosequencing. RESULTS: In all, 12 patients with "progressive" versus 12 with "nonprogressive" nondysplastic Barrett esophagus were analyzed via methylation array. Forty-four methylation markers were identified that may be able to discriminate between nondysplastic Barrett esophagus that either progress to adenocarcinoma or remain static. Hypomethylation of the recently identified tumor suppressor OR3A4 (probe cg09890332) validated in a separate cohort of samples (median methylation in progressors 67.8% vs 96.7% in nonprogressors; P = 0.0001, z = 3.85, Wilcoxon rank-sum test) and was associated with the progression to adenocarcinoma. There were no differences in copy number between the 2 groups, but a global trend towards hypomethylation in the progressor group was observed. CONCLUSION: Hypomethylation of OR3A4 has the ability to risk stratify the patient with nondysplastic Barrett esophagus and may form the basis of a future surveillance program.

A systematic review of epigenetic biomarkers in progression from non-dysplastic Barrett's oesophagus to oesophageal adenocarcinoma.

OBJECTIVES: The objective of this systematic review is to identify and summarise studies which examine epigenetic biomarkers in patients with Barrett's oesophagus (BO) and their association with progression to oesophageal adenocarcinoma (OADC). BO is a precursor lesion for OADC. There is no clinical test to predict patients who are likely to progress to OADC. An epigenetic biomarker could predict patients who are at high risk of progression from BO to OADC which could facilitate earlier diagnosis and spare those unlikely to develop cancer from regular invasive surveillance endoscopy. SETTING: A systematic search was conducted of the following databases: MEDLINE, MEDLINE in Process, EMBASE, Cochrane Central, ISI Conference Proceedings Citation Index and the British Library's ZETOC. Studies were conducted in secondary and tertiary care settings. PARTICIPANTS: All studies measuring epigenetic change in patients over 18 years old who progressed from non-dysplastic BO to OADC were included. Genetic, in vitro and studies which did not measure progression in the same patient cohort were excluded. Study inclusion and risk of bias of individual eligible studies were assessed in duplicate by two reviewers using a modified Quality in Prognostic Studies tool. RESULTS: 14 studies met the inclusion criteria. 42 epigenetic markers were identified, and 5 studies developed models aiming to predict progression to OADC. CONCLUSIONS: The evidence from this systematic review is suggestive of a role for p16 as an epigenetic biomarker for the progression of BO to OADC. PROSPERO NUMBER: CRD42016038654.

Nanopore sequencing and assembly of a human genome with ultra-long reads.

We report the sequencing and assembly of a reference genome for the human GM12878 Utah/Ceph cell line using the MinION (Oxford Nanopore Technologies) nanopore sequencer. 91.2 Gb of sequence data, representing ∼30× theoretical coverage, were produced. Reference-based alignment enabled detection of large structural variants and epigenetic modifications. De novo assembly of nanopore reads alone yielded a contiguous assembly (NG50 ∼3 Mb). We developed a protocol to generate ultra-long reads (N50 > 100 kb, read lengths up to 882 kb). Incorporating an additional 5× coverage of these ultra-long reads more than doubled the assembly contiguity (NG50 ∼6.4 Mb). The final assembled genome was 2,867 million bases in size, covering 85.8% of the reference. Assembly accuracy, after incorporating complementary short-read sequencing data, exceeded 99.8%. Ultra-long reads enabled assembly and phasing of the 4-Mb major histocompatibility complex (MHC) locus in its entirety, measurement of telomere repeat length, and closure of gaps in the reference human genome assembly GRCh38.

Twisting of distal ileum around end ileostomy: is it a specific complication after laparoscopic subtotal colectomy?

Ulcerative colitis affects 1 in 1000 people in Western cultures. In acute colitis, up to 40% of cases require surgical intervention. In suitable patients laparoscopic subtotal colectomy has become the standard of care. This case series demonstrates the hitherto unreported complication of twisting of an end ileostomy after laparoscopic subtotal colectomy. Each of the cases shared a young age and a slow postoperative recovery. The fact that the ileostomies remained intact after an open approach indicates that the laparoscopic approach (and its limitations) must be at least partly responsible for the initial morbidity in these cases. Limited literature means we can only speculate as to the reason for twisted ileostomy. Apart from the above stated reason, it may be that the minimally invasive approach causes fewer intraperitoneal adhesions than an open approach due to reduced bowel handling, allowing the small bowel to move more freely within the abdomen causing twisting. Numerous studies have applauded the use of minimally invasive colonic resection in cases of inflammatory bowel disease; however, great care must be taken to avoid this specific complication occurring when using a laparoscopic approach.