Background Paget’s disease of bone is characterised by focal abnormalities of bone turnover resulting in various complications. It often presents at an advanced stage with irreversible bone damage. At this point, the symptomatic benefits of treatment are blunted. Paget’s disease of bone has a strong genetic component and the most important susceptibility gene is SQSTM1 . Carriers of SQSTM1 mutations have more severe disease with an earlier age of onset than non-carriers and about 80% develop Paget’s disease of bone by the seventh decade. Objectives The primary objective was to determine if zoledronic acid could prevent new Paget’s disease of bone-like bone lesions in SQSTM1 mutation carriers. Secondary objectives were to assess if zoledronic acid could: modify existing Paget’s disease of bone lesions, markers of bone turnover, quality of life, bone pain, anxiety, depression or the risk of complications. Design This was a multicentre, double-blind placebo-controlled trial. Genetic screening of the SQSTM1 gene was offered to people with a family history of Paget’s disease of bone, identifying 222 mutation carriers who consented to participate. At baseline, a radionuclide bone scan was performed; biochemical markers of bone turnover were measured and questionnaires on pain, quality of life and mental health were completed. Participants completed annual biochemical markers measurements and questionnaires. Adverse events were recorded on a continuous basis. At the end of study, the bone scan was repeated, along with biochemical markers and questionnaires. Setting This was a multicentre trial that was conducted at 27 secondary care referral centres for bone disease in 7 countries. All the visits were conducted within a secondary healthcare setting. Participants Interventions Participants were randomly allocated to receive a single infusion of the bisphosphonate zoledronic acid 5 mg or an identical placebo. Main outcome measures The study’s primary outcome measure was defined as the total number of participants who developed new bone lesions on radionuclide bone scans with the characteristics of PDB between the baseline visit and the final end-of-study visit. The secondary outcomes included the number of new PDB bone lesions on radionuclide bone scans, change in the activity of existing PDB bone lesions at the end of study assessed by radionuclide scans; changes in plasma type I collagen C-telopeptides (CTX); plasma procollagen type I amino-terminal propeptide (PINP); serum bone-specific alkaline phosphatase (BAP); quality of life assessed by SF-36, BPI, HADS questionnaires; the presence and severity of localized bone pain assessed by the BPI pain manikin; and the development of PDB-related skeletal events (PDRSE) in SQSTM1 mutation carriers including new lesions, complications (fractures, deformity), or the need for treatment of PDB. Methods This was a multicentre, double-blind placebo-controlled trial. Genetic screening of the SQSTM1 gene was offered to people with a family history of Paget’s disease of bone, identifying 222 mutation carriers who consented to participate. At baseline, a radionuclide bone scan was performed; biochemical markers of bone turnover were measured and questionnaires on pain, quality of life and mental health were completed. Participants were randomly allocated to receive a single infusion of the bisphosphonate zoledronic acid 5 mg or an identical placebo. Participants completed annual biochemical markers measurements and questionnaires. Adverse events were recorded on a continuous basis. At the end of study, the bone scan was repeated, along with biochemical markers and questionnaires. Results At baseline, 21/222 individuals (9.5%) had evidence of Paget’s disease of bone on bone scans. In the placebo group, 2/90 individuals (2.2%) developed new bone lesions compared with 0/90 (0%) in the zoledronic acid group (odds ratio 0.41, 95% confidence interval 0.00 to 3.43; p = 0.25). Eight participants in the placebo group had a poor outcome (new/unchanged/progressing lesions) compared with none in the zoledronic acid group (odds ratio 0.08, 95% confidence interval 0.00 to 0.42; p = 0.003). With placebo, 1/29 (3.4%) lesions disappeared compared with 13/15 (86.6%) with zoledronic acid ( p < 0.0001). One participant allocated to placebo required treatment with zoledronic acid due to a complication of Paget’s disease of bone. Significant reductions were observed for serum C-terminal telopeptide ( p < 0.0001), bone-specific alkaline phosphatase ( p = 0.0003) and N -terminal propeptide of type I procollagen ( p < 0.0001) in the zoledronic acid group compared with placebo. There was no significant difference between groups in quality of life, pain, anxiety or depression. Conclusion Genetic testing for SQSTM1 mutations coupled with bone scan examination can detect early Paget’s disease of bone in those with a family history of the disorder and zoledronic acid treatment can favourably modify its evolution. The study had some limitations. First, 9.5% of participants already had Paget’s disease of bone, reducing power. Second, only two participants developed new lesions compared to the 15% expected. The small number of events meant the study was underpowered for the primary outcome and we were unable to adjust analyses for co-variates or family clustering. An extended follow-up in the zoledronic acid in the prevention of Paget’s disease – long-term extension study is in progress and will provide valuable information on the duration of effects of a single zoledronic acid infusion. It will be important to consider a health economic analysis to model the effects of genetic testing, scanning and zoledronic acid treatment, to evaluate long-term clinical and symptomatic benefits. Study registration Current Controlled Trials ISRCTN11616770. Funding This award was funded by the Efficacy and Mechanism Evaluation (EME) programme, a Medical Research Council (MRC) and National Institute for Health and Care Research (NIHR) partnership. This is published in full in Efficacy and Mechanism Evaluation ; Vol. 11, No. 10. See the NIHR Funding and Awards website for further award information.

Searchable abstracts of presentations at key conferences in endocrinology ISSN 1470-3947 (print) | ISSN 1479-6848 (online)

IntroductionPaget's disease of bone (PDB) frequently presents at an advanced stage with irreversible skeletal damage. Clinical outcomes might be improved by earlier diagnosis and prophylactic treatment.MethodsWe randomised 222 individuals at increased risk of PDB because of pathogenic SQSTM1 variants to receive 5 mg zoledronic acid (ZA) or placebo. The primary outcome was new bone lesions assessed by radionuclide bone scan. Secondary outcomes included change in existing lesions, biochemical markers of bone turnover and skeletal events related to PDB.ResultsThe median duration of follow-up was 84 months (range 0-127) and 180 participants (81%) completed the study. At baseline, 9 (8.1%) of the ZA group had PDB lesions vs 12 (10.8%) of the placebo group. Two of the placebo group developed new lesions versus none in the ZA group (OR 0.41, 95% CI 0.00 to 3.43, p=0.25). Eight of the placebo group had a poor outcome (lesions which were new, unchanged or progressing) compared with none of the ZA group (OR 0.08, 95% CI 0.00 to 0.42, p=0.003). At the study end, 1 participant in the ZA group had lesions compared with 11 in the placebo group. Biochemical markers of bone turnover were significantly reduced in the ZA group. One participant allocated to placebo required rescue therapy with ZA because of symptomatic disease. The number and severity of adverse events did not differ between groups.ConclusionsGenetic testing for pathogenic SQSTM1 variants coupled with intervention with ZA is well tolerated and has favourable effects on the progression of early PDB.Trial registration numberISRCTN11616770.

Healthcare professionals frequently communicate the benefits of treatments as a relative risk reduction (RRR) in the likelihood of an event occurring. Here we evaluated whether presenting the benefits of osteoporosis treatment as a RRR in fractures compared with an absolute risk reduction (ARR) changed the patient’s attitudes towards accepting treatment. We surveyed 160 individuals attending a specialised osteoporosis clinic for face-to-face consultations between May 2018 and Jan 2021. They were presented with information on RRR for the treatment being considered followed by ARR and after each question were asked about how likely they would be to start treatment on a 5-point scale (1 = very likely, 5 = very unlikely). Participants were less likely to accept treatment when it was presented as ARR (mean score 2.02 vs. 2.67, p < 0.001, 95% CI for difference − 0.82 vs − 0.47) and thirty-eight participants (23.7%) declined treatment with knowledge of their ARR when they would have accepted the same treatment based on the RRR. Individuals who declined treatment had a lower 5-year risk of fracture than those who accepted treatment (9.0 vs. 12.5%, p < 0.001, 95% CI − 5.0 to − 1.6) and as fracture risk decreased, the participant was less likely to accept treatment (Spearman r − 0.32, 95% CI − 0.46 to − 0.17, p ≤ 0.001). Whilst presentation of data as ARR more accurately reflects individual benefit and helps facilitate shared decision-making, clinicians should be aware that this will lead to a proportion of patients with lower fracture risk declining treatment for osteoporosis.

SORCS2 is one of five proteins that constitute the Vps10p-domain receptor family. Members of this family play important roles in cellular processes linked to neuronal survival, differentiation and function. Genetic and functional studies implicate SORCS2 in cognitive function, as well as in neurodegenerative and psychiatric disorders. DNA damage and DNA repair deficits are linked to ageing and neurodegeneration, and transient neuronal DNA double-strand breaks (DSBs) also occur as a result of neuronal activity. Here, we report a novel role for SORCS2 in DSB formation. We show that SorCS2 loss is associated with elevated DSB levels in the mouse dentate gyrus and that knocking out SORCS2 in a human neuronal cell line increased Topoisomerase IIβ-dependent DSB formation and reduced neuronal viability. Neuronal stimulation had no impact on levels of DNA breaks in vitro, suggesting that the observed differences may not be the result of aberrant neuronal activity in these cells. Our findings are consistent with studies linking the VPS10 receptors and DNA damage to neurodegenerative conditions.

The neuromodulatory gene DISC1 is disrupted by a t(1;11) translocation that is highly penetrant for schizophrenia and affective disorders, but how this translocation affects DISC1 function is incompletely understood. N-methyl-D-aspartate receptors (NMDAR) play a central role in synaptic plasticity and cognition, and are implicated in the pathophysiology of schizophrenia through genetic and functional studies. We show that the NMDAR subunit GluN2B complexes with DISC1-associated trafficking factor TRAK1, while DISC1 interacts with the GluN1 subunit and regulates dendritic NMDAR motility in cultured mouse neurons. Moreover, in the first mutant mouse that models DISC1 disruption by the translocation, the pool of NMDAR transport vesicles and surface/synaptic NMDAR expression are increased. Since NMDAR cell surface/synaptic expression is tightly regulated to ensure correct function, these changes in the mutant mouse are likely to affect NMDAR signalling and synaptic plasticity. Consistent with these observations, RNASeq analysis of the translocation carrier-derived human neurons indicates abnormalities of excitatory synapses and vesicle dynamics. RNASeq analysis of the human neurons also identifies many differentially expressed genes previously highlighted as putative schizophrenia and/or depression risk factors through large-scale genome-wide association and copy number variant studies, indicating that the translocation triggers common disease pathways that are shared with unrelated psychiatric patients. Altogether, our findings suggest that translocation-induced disease mechanisms are likely to be relevant to mental illness in general, and that such disease mechanisms include altered NMDAR dynamics and excitatory synapse function. This could contribute to the cognitive disorders displayed by translocation carriers.

The neuromodulatory gene DISC1 is disrupted by a t(1;11) translocation that is highly penetrant for schizophrenia and affective disorders, but how this translocation affects DISC1 function is incompletely understood. N-methyl-D-aspartate receptors (NMDAR) play a central role in synaptic plasticity and cognition, and are implicated in the pathophysiology of schizophrenia through genetic and functional studies. We show that the NMDAR subunit GluN2B complexes with DISC1-associated trafficking factor TRAK1, while DISC1 interacts with the GluN1 subunit and regulates dendritic NMDAR motility in cultured mouse neurons. Moreover, in the first mutant mouse that models DISC1 disruption by the translocation, the pool of NMDAR transport vesicles and surface/synaptic NMDAR expression are increased. Since NMDAR cell surface/synaptic expression is tightly regulated to ensure correct function, these changes in the mutant mouse are likely to affect NMDAR signalling and synaptic plasticity. Consistent with these observations, RNASeq analysis of the translocation carrier-derived human neurons indicates abnormalities of excitatory synapses and vesicle dynamics. RNASeq analysis of the human neurons also identifies many differentially expressed genes previously highlighted as putative schizophrenia and/or depression risk factors through large-scale genome-wide association and copy number variant studies, indicating that the translocation triggers common disease pathways that are shared with unrelated psychiatric patients. Altogether, our findings suggest that translocation-induced disease mechanisms are likely to be relevant to mental illness in general, and that such disease mechanisms include altered NMDAR dynamics and excitatory synapse function. This could contribute to the cognitive disorders displayed by translocation carriers. Introduction N-methyl-D-aspartate receptors (NMDAR) are vital for synaptic plasticity and cognitive processes, and are strongly implicated in the pathophysiology of schizophrenia in particular. GRIN2A, encoding the NMDAR GluN2A subunit, © The Author(s) 2018 OpenAccessThis article is licensedunder aCreativeCommonsAttribution 4.0 International License,whichpermits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changesweremade. The images or other third partymaterial in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to thematerial. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/. Correspondence: J. Kirsty Millar (kirsty.millar@igmm.ed.ac.uk) Centre for Genomic and Experimental Medicine, MRC Institute of Genetics and Molecular Medicine at the University of Edinburgh, Edinburgh, UK Xtuit Pharmaceuticals, Waltham, MA, USA Full list of author information is available at the end of the article. These authors contributed equally: Kyriakos D. Economides, Ellen Grünewald, Paraskevi Makedonopoulou 12 34 56 78 90 () :,; 12 34 56 78 90 () :,; 1 2 3 4 5 6 7 8 9 0 () :,; 12 34 56 78 90 () :,; was recently reported to show genome-wide significant association with schizophrenia, while genomic copy number variants (CNVs) enriched in schizophrenia patients target GRIN1, encoding the GluN1 subunit. Such findings support a role for NMDAR in psychiatric disorders, but direct mechanistic insight is still required. NMDAR function is regulated at many stages, including subunit expression and composition, and dynamic modulation of surface and synaptic levels. The latter can be elicited through control of NMDAR forward trafficking to the plasma membrane, subsequent insertion into synapses, or endocytosis. The obligatory GluN1 subunit is incorporated into all NMDAR, along with other subunit types including GluN2A/B. GluN1 is synthesised in excess and stored within the endoplasmic reticulum (ER), where NMDAR are assembled prior to transportation to the Golgi and onwards to the cell surface. Every stage of NMDAR forward trafficking is tightly modulated to ensure that the required quantity of receptors is present at the cell surface and synapse. Genetic dysregulation of forward trafficking would be predicted to adversely affect the NMDAR function, with knock-on effects for synapse strength and plasticity. DISC1 is disrupted in a large, multi-generation family by a chromosomal t(1;11) translocation that is linked to major mental illness. DISC1 is critical for several processes in the developing and adult brain, and has been connected to NMDAR function through regulation of downstream processes that underlie synaptic plasticity. DISC1 also regulates neuronal microtubulebased cargo transport, including trafficking of mitochondria, synaptic vesicles and messenger RNAs, and associates with the motor protein adaptors TRAK1 and TRAK2. Here we demonstrate direct interaction between GluN1 and DISC1, and association between GluN2B and TRAK1. Applying a novel live-imaging method, we demonstrate that DISC1 regulates dendritic NMDAR motility. Utilising a mouse model of DISC1 disruption by the translocation, we show that mutant mouse neurons exhibit increased NMDAR fast active transport and cell surface/synaptic NMDAR expression. These observations implicate dysregulated NMDAR dynamics/signalling and excitatory synapse dysfunction in the psychiatric disorders displayed by translocation carriers. In further support of a general disease mechanism revealed by the translocation, we find that it impacts the biological pathways highlighted by independent schizophrenia and depression GWAS and CNV studies. Materials and methods Detailed materials and methods for all experiments are provided in the Supplementary information. Essential information is included below. Generation of induced pluripotent stem cells (IPSC) from