Sensitized mutagenesis screen in Factor V Leiden mice identifies thrombosis suppressor loci.

Factor V Leiden (F5L ) is a common genetic risk factor for venous thromboembolism in humans. We conducted a sensitized N-ethyl-N-nitrosourea (ENU) mutagenesis screen for dominant thrombosuppressor genes based on perinatal lethal thrombosis in mice homozygous for F5L (F5L/L ) and haploinsufficient for tissue factor pathway inhibitor (Tfpi+/- ). F8 deficiency enhanced the survival of F5L/LTfpi+/- mice, demonstrating that F5L/LTfpi+/- lethality is genetically suppressible. ENU-mutagenized F5L/L males and F5L/+Tfpi+/- females were crossed to generate 6,729 progeny, with 98 F5L/LTfpi+/- offspring surviving until weaning. Sixteen lines, referred to as "modifier of Factor 5 Leiden (MF5L1-16)," exhibited transmission of a putative thrombosuppressor to subsequent generations. Linkage analysis in MF5L6 identified a chromosome 3 locus containing the tissue factor gene (F3). Although no ENU-induced F3 mutation was identified, haploinsufficiency for F3 (F3+/- ) suppressed F5L/LTfpi+/- lethality. Whole-exome sequencing in MF5L12 identified an Actr2 gene point mutation (p.R258G) as the sole candidate. Inheritance of this variant is associated with suppression of F5L/LTfpi+/- lethality (P = 1.7 × 10-6), suggesting that Actr2p.R258G is thrombosuppressive. CRISPR/Cas9 experiments to generate an independent Actr2 knockin/knockout demonstrated that Actr2 haploinsufficiency is lethal, supporting a hypomorphic or gain-of-function mechanism of action for Actr2p.R258G Our findings identify F8 and the Tfpi/F3 axis as key regulators in determining thrombosis balance in the setting of F5L and also suggest a role for Actr2 in this process.

Increased Detection of Celiac Disease With Measurement of Deamidated Gliadin Peptide Antibody Before Endoscopy.

BACKGROUND & AIMS: Celiac disease is underdiagnosed. Many patients are examined by endoscopy, but celiac disease is missed or not detected. We evaluated the accuracy of finger prick-based point-of-care tests in the detection of celiac disease and developed an algorithm for diagnosis. METHODS: We performed a prospective study of 2 groups of patients with celiac disease evaluated at the Royal Hallamshire Hospital in Sheffield (United Kingdom) from March 2013 through February 2014. In group 1, patients at high risk of celiac disease who tested positive for endomysial antibody (n = 55) were evaluated using the Biocard test (BHR Pharmaceuticals, Nuneaton, UK) and the Celiac Quick Test (Biohit Healthcare UK, Ellesmere Port, UK), which measure antibodies to tissue transglutaminase (anti-tTG), and the Simtomax test (Tillotts Pharma, Rheinfelden, Switzerland), which measures deamidated gliadin peptide antibodies (DGP). Patients in group 2 (508 consecutive patients who underwent an endoscopy examination for any indication) received the DGP test, and also were evaluated using a diagnostic algorithm that incorporated results from the DGP test and data on symptoms. In both groups, point-of-care tests were taken at the time of endoscopy and results were compared with results from histologic analyses of duodenal biopsy specimens from all patients. RESULTS: In group 1, the DGP test identified patients with celiac disease with 94.4% sensitivity, the Celiac Quick Test identified patients with 77.8% sensitivity (P = .03 vs the DGP test), and the Biocard test identified patients with 72.2% sensitivity (P = .008 vs the DGP test). In group 2, the DGP test identified patients with celiac disease with 92.7% sensitivity (95% confidence interval, 83.0-97.3), 85.2% specificity (95% confidence interval, 81.5-88.3), a positive predictive value of 49.2% (95% confidence interval, 40.3-58.2), and a negative predictive value of 98.7% (95% confidence interval, 96.8-99.5). Measurement of serum anti-tTG identified patients with celiac disease with 91.2% sensitivity (95% confidence interval, 81.1-96.4), 87.5% specificity (95% confidence interval, 84.0-90.4), a positive predictive value of 53.0% (95% confidence interval, 43.6-62.2), and a negative predictive value of 98.5% (95% confidence interval, 96.5-99.4). The algorithm identified patients with celiac disease with 98.5% sensitivity; its use could reduce duodenal biopsies by 35%. CONCLUSIONS: In a prospective study, a test for DGP identified patients with celiac disease with similar levels of sensitivity and specificity as standard serologic analysis of anti-tTG. Use of the DGP test before endoscopy could increase the accuracy of the diagnosis of celiac disease. Further studies, in lower-prevalence populations, are required to assess the impact of the test in clinical practice.

Point-of-care testing for celiac disease has a low sensitivity in endoscopy.

BACKGROUND: Celiac disease (CD) is a common but underdiagnosed condition. A rapid point-of-care test (POCT) could reduce lead times and missed diagnoses. OBJECTIVE: To assess the utility of an immunoglobulin (Ig) A tissue transglutaminase (TTG) antibody POCT in an endoscopic setting. DESIGN: Prospective observational study. SETTING: A single UK university hospital. PATIENTS: Patients presenting with suspected CD, known CD, and routine endoscopy for upper GI symptoms. INTERVENTIONS: All patients were tested with POCT, serum TTG, endomysial antibody (EMA), and upper GI endoscopy with duodenal biopsies at the same visit. MAIN OUTCOME MEASUREMENTS: Comparison was made with histology in all cases, with villous atrophy regarded as diagnostic of CD. RESULTS: A total of 576 patients (63.5% female, mean [± standard deviation] age 49.7 years [± 17.6 years]) were recruited. A total of 523 patients had no prior diagnosis of CD, and 53 patients had known CD coming for reassessment. A total of 117 patients were newly diagnosed with CD, and 82 were positively identified by the POCT. Sensitivity, specificity, positive predictive value, and negative predictive value were 70.1%, 96.6%, 85.4%, and 91.8%, respectively. In comparison, TTG and EMA both performed significantly better than the POCT. Sensitivity and specificity of TTG were 91.0% and 83.5%, respectively, and EMA were 83.8% and 97.5%, respectively. Of patients with known CD coming for reassessment, 26 had villous atrophy, and POCT results were positive in 16 (61.5%). There was poor agreement between POCT and standard serology. LIMITATIONS: High pre-test probability of CD. CONCLUSION: The performance of this POCT was disappointing compared with standard serology and cannot at present be recommended within the context of an endoscopy unit.

Identification of genomic loci regulating platelet plasminogen activator inhibitor-1 in mice.

BACKGROUND: Plasminogen activator inhibitor-1 (PAI-1, Serpine1) is an important circulating fibrinolysis inhibitor. PAI-1 exists in 2 pools, packaged within platelet α-granules and freely circulating in plasma. Elevated plasma PAI-1 levels are associated with cardiovascular disease. However, little is known about the regulation of platelet PAI-1 (pPAI-1). OBJECTIVES: We investigated the genetic control of pPAI-1 levels in mice and humans. METHODS: We measured pPAI-1 antigen levels via enzyme-linked immunosorbent assay in platelets isolated from 10 inbred mouse strains, including LEWES/EiJ (LEWES) and C57BL/6J (B6). LEWES and B6 were crossed to produce the F1 generation, B6LEWESF1. B6LEWESF1 mice were intercrossed to produce B6LEWESF2 mice. These mice were subjected to genome-wide genetic marker genotyping followed by quantitative trait locus analysis to identify pPAI-1 regulatory loci. RESULTS: We identified differences in pPAI-1 between several laboratory strains, with LEWES having pPAI-1 levels more than 10-fold higher than those in B6. Quantitative trait locus analysis of B6LEWESF2 offspring identified a major pPAI-1 regulatory locus on chromosome 5 from 136.1 to 137.6 Mb (logarithm of the odds score, 16.2). Significant pPAI-1 modifier loci on chromosomes 6 and 13 were also identified. CONCLUSION: Identification of pPAI-1 genomic regulatory elements provides insights into platelet/megakaryocyte-specific and cell type-specific gene expression. This information can be used to design more precise therapeutic targets for diseases where PAI-1 plays a role.

High definition endoscopy with or without I-Scan increases the detection of celiac disease during routine endoscopy.

BACKGROUND AND AIMS: Celiac disease remains underdiagnosed at endoscopy. We aimed to assess the utility of I-Scan (virtual chromo-endoscopy) to improve sensitivity of endoscopy to detect markers of villous atrophy in this condition. METHODS: Patients from 2 UK hospitals were studied in 3 groups. Group 1: standard high definition, white light endoscopy (WLE); Group 2: WLE plus I-Scan; Group 3: non-high definition control group. The presence of endoscopic markers was recorded. At least 4 duodenal biopsies were taken from all patients. Serology was performed concurrently and observations were compared with histology. RESULTS: 758 patients (62% female, mean age 52) were recruited (Group 1: 230; Group 2: 228; Group 3: 300). 135 (17.8%) new diagnoses of coeliac disease were made (21 Group 1; 24 Group 2; 89 Group 3). The sensitivity for detection of endoscopic markers of villous atrophy was significantly higher in both Group 1 (85.7%, p=0.0004) and Group 2 (75%, p=0.005) compared to non-high definition controls (41.6%). There was no significant difference between high definition only and I-Scan groups (p=0.47). In non-high definition endoscopy a missed diagnosis was associated with lesser degrees of villous atrophy (p=0.019) and low tTG titre (p=0.007). CONCLUSIONS: High definition endoscopy with or without I-Scan increases the detection of celiac disease during routine endoscopy.