CNV and Schizophrenia Working Groups of the Psychiatric Genomics Consortium; Psychosis Endophenotypes International Consortium. [including Waddington J]. Contribution of copy number variants to schizophrenia from a genome-wide study of 41,321 subjects. Nat Genet. 2017 Jan;49(1):27-35. PMID: 27869829
John Waddington writes about his group’s participation in a global research endeavour that has produced a series of articles in Nature, Nature Genetics and Nature Neuroscience on the pathobiology of schizophrenia The Psychiatric Genomics Consortium (PGC) unites investigators around the world to conduct meta- and mega-analyses of genome-wide genomic data on psychiatric disorders, to achieve goals that cannot be reached by individual or indeed most national programmes. Its website (www.med.unc.edu/pgc) provides information about the organization, implementation and results of the PGC. This consortium began in early 2007 and has rapidly become a collaborative confederation of investigators from 38 countries. There are samples from more than 900,000 individuals currently in analysis, and this number is growing rapidly. The PGC is the largest consortium and the largest biological experiment in the history of psychiatry.
From 2007-11, the PGC focused on several disorders, from schizophrenia through to autism, attention-deficit hyperactivity disorder, bipolar disorder and major depressive disorder. These now extend to large studies of eating disorders, substance use disorders, obsessive-compulsive disorder/Tourette’s Syndrome and post-traumatic stress disorder. Initially, the PGC focused on common single nucleotide polymorphisms (SNPs) but has expanded to include copy number variation (CNVs) and uncommon/rare genetic variation. The PGC has received funding from many sources. It has relied heavily on the goodwill of its members and their donated effort, with the establishment andgenotyping of its primary studies funded by a wide range of national, international and commercial entities.
We have been involved in the Schizophrenia Working Group of the PGC for many years, from its progenitor organisation the International Schizophrenia Consortium, primarily through substantial funding from the Wellcome Trust for five centres across the island of Ireland (one led by us) to contribute DNA from well characterised patient populations to a national dataset curated at Trinity College Dublin. This dataset has then been shared with the PGC. The resultant studies have evolved from the first investigation of CNVs in schizophrenia (3,391 cases, 3,181 controls; Nature 2008; 455: 237-41), through to the largest GWAS study on schizophrenia undertaken to date (36,989 cases, 113,075 controls; Nature 2014; 511: 421-7), to this most recent publication (21,094 cases, 20,227 controls; Nature Genetics 2017; 49: 27-35), the largest study of CNVs in schizophrenia yet undertaken. This has been, and continues to be, an exemplary, rewarding journey of global collaboration to illuminate the pathobiology of the intractable human condition that is psychotic illness.
Chion A, O’Sullivan JM, Drakeford C, Bergsson G, Dalton N, Aguila S, Ward S, Fallon PG, Brophy TM, Preston RJ, Brady L, Sheils, O, Laffan M, McKinnon TA, O’Donnell JS. N-linked glycans within the A2 domain of von Willebrand factor modulate macrophage-mediated clearance. Blood. 2016 Oct 13;128(15):1959-1968. PMID: 27554083.
Jamie Marie O’Sullivan writes about this study:
Von Willebrand factor (VWF) is a large multimeric plasma sialoglycoprotein that plays two critical roles in normal haemostasis. First it mediates platelet adhesion to exposed subendothelial collagen at sites of vascular injury. Second, VWF acts as a carrier molecule for procoagulant factor VIII, thereby protecting it from premature proteolytic degradation and clearance. Deficiency of either VWF (von Willebrand disease, VWD) or FVIII (Haemophilia A) is associated with a significant bleeding phenotype. Conversely, elevated plasma levels of the VWF-FVIII complex constitute a dose dependent risk factor for both venous and arterial thrombosis. Consequently, understanding the factors that determine how plasma VWF levels are regulated is not only of basic scientific interest, but also direct clinical importance.
Despite the fact that type 1 von Willebrand disease constitutes the most common inherited bleeding disorder worldwide, the mechanisms underlying the reduced plasma VWF levels in these patients is not well established. However, emerging evidence suggests that reduced circulatory half-life may be important in a significant number of patients. However the biological mechanisms underlying VWF clearance from the plasma remains elusive. Work is on-going within the group of Professor James O’Donnell to investigate the importance of specific VWF domains in modulating half-life in vivo.
In the October issue of Blood the group published novel findings demonstrating a critical role for VWF glycosylation in determining its circulatory half-life. By examining the clearance of various truncated fragments of VWF, we observed that the A domains of VWF contain a receptor-recognition site important in mediating VWF binding to macrophages in vitro, and in regulating VWF clearance by macrophages in vivo. Furthermore site-directed mutagenesis demonstrated a key role for N-linked glycan structures at position N1515 and N1574 within the A domains in protecting VWF against macrophage-mediated clearance. More specifically, the protective effect of these large complex N-linked glycan structures may be due to steric hindrance, with shielding of cryptic binding sites for macrophage clearance receptor low density lipoprotein receptor-related protein 1 (LRP1).
Defining the mechanisms underpinning VWF clearance is not only of direct translational relevance, but may also have important implications for the development of novel therapeutic agents with significant commercial appeal. For example, the estimated cost of clotting factor concentrates to the global market is predicted to exceed €10 billion per annum by 2020. It is therefore perhaps unsurprising that major pharmaceutical companies (including Baxter®, Bayer®, Novo Nordisk® and Octapharma®) are actively pursuing development of longer-acting coagulation factor products (including VWF and FVIII) as a priority. Our novel findings further scientific understanding in relation to the molecular mechanisms involved in regulating coagulation glycoprotein clearance from plasma.
McGettrick AF, Corcoran SE, Barry PJ, McFarland J, Crès C, Curtis AM, Franklin E, Corr SC, Mok KH, Cummins EP, Taylor CT, O’Neill LA, Nolan DP. Trypanosoma brucei metabolite indolepyruvate decreases HIF-1α and glycolysis in macrophages as a mechanism of innate immune evasion. Proc Natl Acad Sci U S A. 2016 Nov 29;113(48):E7778-E7787. PMID: 27856732.
Dr. Anne McGettrick and Sarah Corcoran at Trinity College Dublin lead a team of researchers including Dr. Annie Curtis (now at MCT) on a study that uncovered how the African parasites trypanosomes evade the immune system in their hosts, The biochemists have unearthed a metabolic by-product of trypanosome activity known as indolepyruvate modulates the inflammatory response of the host and evades immune detection. This discovery may offer excellent possibilities for developing anti-trypanosome drugs and therapies because inhibiting the production of indolepyruvate may be key in fighting the parasite. Full details can be found here https://www.tcd.ie/news_events/articles/solving-a-putrid-camel-pee-riddle-may-aid-millions-affected-by-sleeping-sickness/7385