The rapidly evolving X-linked MIR-506 family fine-tunes spermatogenesis to enhance sperm competition

Despite rapid evolution across eutherian mammals, the X-linked MIR-506 family miRNAs are located in a region flanked by two highly conserved protein-coding genes (SLITRK2 and FMR1) on the X chromosome. Intriguingly, these miRNAs are predominantly expressed in the testis, suggesting a potential role in spermatogenesis and male fertility. Here, we report that the X-linked MIR-506 family miRNAs were derived from the MER91C DNA transposons. Selective inactivation of individual miRNAs or clusters caused no discernible defects, but simultaneous ablation of five clusters containing 19 members of the MIR-506 family led to reduced male fertility in mice. Despite normal sperm counts, motility, and morphology, the KO sperm were less competitive than wild-type sperm when subjected to a polyandrous mating scheme. Transcriptomic and bioinformatic analyses revealed that these X-linked MIR-506 family miRNAs, in addition to targeting a set of conserved genes, have more targets that are critical for spermatogenesis and embryonic development during evolution. Our data suggest that the MIR-506 family miRNAs function to enhance sperm competitiveness and reproductive fitness of the male by finetuning gene expression during spermatogenesis.

The Rapidly Evolving X-linked miR-506 Family Finetunes Spermatogenesis to Enhance Sperm Competition

Despite rapid evolution across eutherian mammals, the X-linked miR-506 family miRNAs are located in a region flanked by two highly conserved protein-coding genes (Slitrk2 and Fmr1) on the X chromosome. Intriguingly, these miRNAs are predominantly expressed in the testis, suggesting a potential role in spermatogenesis and male fertility. Here, we report that the X-linked miR-506 family miRNAs were derived from the MER91C DNA transposons. Selective inactivation of individual miRNAs or clusters caused no discernable defects, but simultaneous ablation of five clusters containing nineteen members of the miR-506 family led to reduced male fertility in mice. Despite normal sperm counts, motility and morphology, the KO sperm were less competitive than wild-type sperm when subjected to a polyandrous mating scheme. Transcriptomic and bioinformatic analyses revealed that these X-linked miR-506 family miRNAs, in addition to targeting a set of conserved genes, have more targets that are critical for spermatogenesis and embryonic development during evolution. Our data suggest that the miR-506 family miRNAs function to enhance sperm competitiveness and reproductive fitness of the male by finetuning gene expression during spermatogenesis.

The changing vaccine landscape: rates of COVID-19 vaccine acceptance and hesitancy in young adults during vaccine rollout

AIMS

Development and rollout of vaccines offers the best opportunity for population protection against the SARS-CoV-2 (COVID-19) virus. However, hesitancy towards the vaccines might impede successful uptake in the United Kingdom, particularly in young adults who demonstrate the highest rates of hesitancy. This prospective study explored COVID-19 vaccine hesitancy in young adults and whether the reasons behind these attitudes changed during the initial stages of the United Kingdom's vaccine rollout.

METHOD

Data on vaccination intention were collected from a British university student cohort at three time points: October 2020, February 2021, and March 2021. This online survey included items on intention to receive a vaccine and a free-text response for the reasons behind this intention. Cochran's Q tests examined changes in rates of hesitancy and acceptance over time and free-text responses were analysed thematically.

RESULTS

At baseline, 893 students provided data, with 476 participants completing all three time points. Hesitancy declined over time, with 29.4% of participants expressing hesitancy at baseline, reducing to 9.1% at wave 2 and 5.9% at wave 3. The most commonly endorsed themes for those willing to accept a vaccine were self-protection against COVID-19 and pro-social reasons, including protecting the population or unspecific others, and ending the pandemic/returning to normal life. The most commonly endorsed hesitancy themes related to 'confidence' in the vaccines and potential personal risk, including insufficient testing/scientific evidence, concern about side effects, and long-term effects. These reasons remained the most commonly endorsed at both waves 2 and 3.

CONCLUSIONS

While a decline in hesitancy was observed over time, the key reasons behind both vaccine acceptance and hesitancy remained consistent. Reasons behind hesitancy aligned with those of the general public, providing support for the use of generalist interventions. Pro-social reasons frequently underpinned vaccine acceptance, so cohort-specific interventions targeting those factors may be of benefit.

Small RNA shuffling between murine sperm and their cytoplasmic droplets during epididymal maturation

Reports that mouse sperm gain small RNAs from the epididymosomes secreted by epididymal epithelial cells and that these "foreign" small RNAs act as an epigenetic information carrier mediating the transmission of acquired paternal traits have drawn great attention because the findings suggest that heritable information can flow from soma to germ line, thus invalidating the long-standing Weismann's barrier theory on heritable information flow. Using small RNA sequencing (sRNA-seq), northern blots, sRNA in situ hybridization, and immunofluorescence, we detected substantial changes in the small RNA profile in murine caput epididymal sperm (sperm in the head of the epididymis), and we further determined that the changes resulted from sperm exchanging small RNAs, mainly tsRNAs and rsRNAs, with cytoplasmic droplets rather than the epididymosomes. Moreover, the murine sperm-borne small RNAs were mainly derived from the nuclear small RNAs in late spermatids. Thus, caution is needed regarding sperm gaining foreign small RNAs as an underlying mechanism of epigenetic inheritance.

Investigating a psychological model of mental conditions and coping during the COVID-19 pandemic driven by participatory methods

BACKGROUND

There is evidence of increased mental health problems during the early stages of the COVID-19 pandemic. We aimed to identify the factors that put certain groups of people at greater risk of mental health problems.

METHODS

We took a participatory approach, involving people with lived experience of mental health problems and/or carers, to generate a set of risk factors and potential moderators of the effects of COVID on mental health. An online cross-sectional survey was completed by 1464 United Kingdom residents between 24th April and 27th June 2020. The survey had questions on whether respondents were existing mental health service users and or carers, level of depression (PHQ9) and anxiety (GAD7), demographics, threat and coping appraisals, perceived resilience (BRS), and specific coping behaviours (validated as part of this study). The relationship between responses and coping strategies was measured using tetrachoric correlations. Structural equation modelling was used to test the model.

RESULTS

A model significantly fit our data (rel χ² = 2.05, RMSEA = 0.029 95%, CI (0.016, 0.042), CFI = 0.99, TLI = 0.98, SRMR = 0.014). Age and coping appraisal predicted anxiety and depression. Whereas, threat appraisal and ethnicity only predicted anxiety, and resilience only predicted depression. Additionally, specific coping behaviours predicted anxiety and depression, with overlap on distraction.

CONCLUSIONS

Some, but not all, risk factors significantly predict anxiety and depression. While there is a relationship between anxiety and depression, different factors may put people at greater risk of one or the other during the pandemic.

Role of immunosuppression in patients with lymphocytic myocarditis and myocardial parvovirus B19 with or without human herpesvirus 6 co-presence

Background

Parvovirus B19 (B19V) and Human Herpesvirus 6 (HHV6) are commonly detected in endomyocardial biopsy (EMB) specimens of patients with myocarditis symptoms. Whether B19V- and HHV6-DNA belong to the cardiac bio-portfolio remains unclear [1,2]. Until today, the role of B19V-/HHV6-DNA presence in myocarditis is doubtful. Both viruses have been detected in the myocardium, even independent of cardiac inflammation. Yet, their contribution to myocarditis remains controversial. The European Society of Cardiology guidelines exclude the use of immunosuppression in patients with virus-associated myocarditis [3]. Whether myocarditis patients with the presence of B19V-DNA alone or with HHV6-DNA in EMB findings can be treated using immunosuppression, remains a delicate question for clinicians.

Methods

931 patients with unexplained heart failure symptoms underwent EMB investigation to determine the underlying cause. Patients with low-levels (<1000 copies/μg DNA) of B19V-DNA and HHV6-DNA were identified. A sub-cohort of 28 patients who suffered from chronic-persistent lymphocytic myocarditis with ongoing symptoms was treated with azathioprine 100 mg once daily and prednisolone 1 mg/kg/day tapered down by 10 mg every two weeks followed by a second EMB. Twenty out of 28 patients had B19V-DNA only (mean LVEF=38%, age=47±15) and eight patients had B19V-/HHV6-DNA copresence (mean LVEF=39%, age=42±10). Patients with systemic infections were excluded. Both cohorts received standard heart failure medications. Continuous variables are expressed as mean±SD.

Results

B19V-DNA alone and in the presence of HHV6-DNA was detectable in the EMB of 377 and 63 patients, respectively. Following the immunosuppression course, the patients with B19V-DNA only and those with B19V-/HHV6-DNA showed complete resolution of inflammation in 12/20 and 5/8 patients, New York Heart Association (NYHA) functional class improvement in 9/20 and 4/8 patients, LVEF improvement by 8.0±13.8% (p<0.05) and 8.4±9.6% (p<0.05), and a reduction of LVEDD by 3.8±6.1mm (p<0.05) and 1.0±7.7mm (p>0.05), respectively. Importantly, following immunosuppression B19V and HHV6-DNA copy numbers went down from 186±266 to 130±186 copies/μg DNA and from 71±141 to 58±143 copies/μg DNA, respectively.

Conclusion

Chronic lymphocytic myocarditis patients with persistent B19V-DNA even in co-presence of HHV6-DNA may benefit from combined immunosuppression therapy. The therapy is clinically effective and safe to reduce cardiac inflammation independent of B19V- and HHV6-DNA copy numbers. In conclusion, we show for the first time that cases with chronic lymphocytic myocarditis can be principally treated with immunosuppression, despite B19V-/HHV6-DNA EMB presence.

Funding Acknowledgement

Type of funding sources: Public Institution(s). Main funding source(s): Berlin Institute of Health-Center for Regenerative Therapies

Evaluation of prognostic risk models for postoperative pulmonary complications in adult patients undergoing major abdominal surgery: a systematic review and international external validation cohort study

BACKGROUND

Stratifying risk of postoperative pulmonary complications after major abdominal surgery allows clinicians to modify risk through targeted interventions and enhanced monitoring. In this study, we aimed to identify and validate prognostic models against a new consensus definition of postoperative pulmonary complications.

METHODS

We did a systematic review and international external validation cohort study. The systematic review was done in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. We searched MEDLINE and Embase on March 1, 2020, for articles published in English that reported on risk prediction models for postoperative pulmonary complications following abdominal surgery. External validation of existing models was done within a prospective international cohort study of adult patients (≥18 years) undergoing major abdominal surgery. Data were collected between Jan 1, 2019, and April 30, 2019, in the UK, Ireland, and Australia. Discriminative ability and prognostic accuracy summary statistics were compared between models for the 30-day postoperative pulmonary complication rate as defined by the Standardised Endpoints in Perioperative Medicine Core Outcome Measures in Perioperative and Anaesthetic Care (StEP-COMPAC). Model performance was compared using the area under the receiver operating characteristic curve (AUROCC).

FINDINGS

In total, we identified 2903 records from our literature search; of which, 2514 (86·6%) unique records were screened, 121 (4·8%) of 2514 full texts were assessed for eligibility, and 29 unique prognostic models were identified. Nine (31·0%) of 29 models had score development reported only, 19 (65·5%) had undergone internal validation, and only four (13·8%) had been externally validated. Data to validate six eligible models were collected in the international external validation cohort study. Data from 11 591 patients were available, with an overall postoperative pulmonary complication rate of 7·8% (n=903). None of the six models showed good discrimination (defined as AUROCC ≥0·70) for identifying postoperative pulmonary complications, with the Assess Respiratory Risk in Surgical Patients in Catalonia score showing the best discrimination (AUROCC 0·700 [95% CI 0·683-0·717]).

INTERPRETATION

In the pre-COVID-19 pandemic data, variability in the risk of pulmonary complications (StEP-COMPAC definition) following major abdominal surgery was poorly described by existing prognostication tools. To improve surgical safety during the COVID-19 pandemic recovery and beyond, novel risk stratification tools are required.

FUNDING

British Journal of Surgery Society.

Uncoupling transcription and translation through miRNA-dependent poly(A) length control in haploid male germ cells

As one of the post-transcriptional regulatory mechanisms, uncoupling of transcription and translation plays an essential role in development and adulthood physiology. However, it remains elusive how thousands of mRNAs get translationally silenced while stability is maintained for hours or even days before translation. In addition to oocytes and neurons, developing spermatids display significant uncoupling of transcription and translation for delayed translation. Therefore, spermiogenesis represents an excellent in vivo model for investigating the mechanism underlying uncoupled transcription and translation. Through full-length poly(A) deep sequencing, we discovered dynamic changes in poly(A) length through deadenylation and re-polyadenylation. Deadenylation appeared to be mediated by microRNAs (miRNAs), and transcripts with shorter poly(A) tails tend to be sequestered into ribonucleoprotein (RNP) granules for translational repression and stabilization. In contrast, re-polyadenylation might allow for translocation of the translationally repressed transcripts from RNP granules to polysomes. Overall, our data suggest that miRNA-dependent poly(A) length control represents a previously unreported mechanism underlying uncoupled translation and transcription in haploid male mouse germ cells.

OP0190 COMPREHENSIVE GENETIC AND FUNCTIONAL ANALYSES OF Fc GAMMA RECEPTORS EXPLAIN RESPONSE TO RITUXIMAB THERAPY FOR AUTOIMMUNE RHEUMATIC DISEASES

Background

Rituximab is widely used to treat rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE) but clinical response varies. Efficacy is determined by the efficiency of depletion, which may depend on a variety of Fc gamma receptor (FcγR)-dependent mechanisms. Previous research was limited by complexity of the FCGR locus, not integrating copy number variation with functional SNP, and small sample size.

Objectives

The study objectives were to assess the effect of the full range of FcγRs variants on depletion, clinical response and functional effect on NK-cell-mediated killing in two rheumatic diseases with a view to personalised B-cell depleting therapies.

Methods

A prospective longitudinal cohort study was conducted in 873 patients [RA=611; SLE=262] from four cohorts (BSRBR-RA and BILAG-BR registries, Leeds RA and Leeds SLE Biologics). For RA, the outcome measures were 3C-DAS28CRP and 2C-DAS28CRP at 6 (+/-3) months post-rituximab (adjusted for baseline DAS28). For SLE, major clinical response (MCR) was defined as improvement of active BILAG-2004 domains to grade C/better at 6 months. B-cell depletion was evaluated by highly-sensitive flow cytometry. Qualitative and quantitative polymorphisms for five major FcγRs were measured using a commercial multiplex ligation-dependent probe amplification. Median NK cell FcγRIIIa expression (CD3-CD56+CD16+) and NK-cell degranulation (CD107a) in the presence of rituximab-coated Daudi/Raji B-cell lines were assessed using flow cytometry.

Results

In RA, for FCGR3A, carriage of V allele (coefficient -0.25 (SE 0.11); p=0.02) and increased copies of V allele (-0.20 (0.09); p=0.02) were associated with greater 2C-DAS28 response. Irrespective of FCGR3A genotype, increased gene copies were associated with a better response. In SLE, 177/262 (67.6%) achieved BILAG response [MCR=34.4%; Partial=33.2%]. MCR was associated with increased copies of FCGR3A-158V allele, OR 1.64 (95% CI 1.12-2.41) and FCGR2C-ORF allele 1.93 (1.09-3.40). Of patients with B-cells data in the combined cohort, 236/413 (57%) achieved complete depletion post-rituximab. Only homozygosity for FCGR3A-158V and increased FCGR3A-158V copy number were associated with increased odds of complete depletion. Patients with complete depletion had higher NK cell FcγRIIIa expression at rituximab initiation than those with incomplete depletion (p=0.04) and this higher expression was associated with improved EULAR response in RA. Moreover, for FCGR3A, degranulation activity was increased in V allele carriers vs FF genotype in the combined cohort; p=0.02.

Conclusion

FcγRIIIa is the major low affinity FcγR and increased copies of the FCGR3A-158V allele, encoding the allotype with a higher affinity for IgG1, was associated with clinical and biological responses to rituximab in two autoimmune diseases. This was supported by functional data on NK cell-mediated cytotoxicity. In SLE, increased copies of the FCGR2C-ORF allele was also associated with improved response. Our findings indicate that enhancing FcγR-effector functions could improve the next generation of CD20-depleting therapies and genotyping could stratify patients for optimal treatment protocols.

References

None

Acknowledgements

This research was funded/supported by the joint funding from the Medical Research Council (MRC) and Versus Arthritis of MATURA (grant codes 36661 and MR/K015346/1). MASTERPLANS was funded by the MRC (grant code MR/M01665X/1). The Leeds Biologics Cohort was part funded by programme grants from Versus Arthritis (grant codes 18475 and 18387), the National Institute for Health Research (NIHR) Leeds Biomedical Research Centre (BRC) and Diagnostic Evaluation Co-operative and the Ann Wilks Charitable Foundation. The BILAG-BR has received funding support from Lupus UK, and unrestricted grants from Roche and GSK.

The functional studies were in part supported through a NIHR/HEFCE Clinical Senior Lectureship and a Versus Arthritis Foundation Fellowship (grant code 19764) to AWM, the Wellcome Trust Institutional Strategic Support Fund to JIR and MYMY (204825/Z/16/Z), NIHR Doctoral Research Fellowship to MYMY (DRF-2014-07-155) and NIHR Clinician Scientist to EMV (CS-2013-13-032). . AWM, INB, JDI and PE were supported by NIHR Senior Investigator awards. Work in JDI’s laboratory is supported by the NIHR Newcastle BRC, the Research Into Inflammatory Arthritis Centre Versus Arthritis, and Rheuma Tolerance for Cure (European Union Innovative Medicines Initiative 2, grant number 777357). INB is funded by the NIHR Manchester BRC.

This article/paper/report presents independent research funded/supported by the NIHR Leeds BRC and the NIHR Guy’s and St Thomas’ BRC. The views expressed are those of the author(s) and not necessarily those of the NIHR or the Department of Health and Social Care.

Disclosure of Interests

Md Yuzaiful Md Yusof: None declared, James Robinson: None declared, Vinny Davies: None declared, Dawn Wild: None declared, Michael Morgan: None declared, John Taylor: None declared, Yasser El-Sherbiny: None declared, David Morris: None declared, Lu Liu: None declared, Andrew Rawstron: None declared, Maya H Buch: None declared, Darren Plant: None declared, Heather Cordell: None declared, John Isaacs: None declared, Ian N. Bruce: None declared, Paul Emery Speakers bureau: Roche, Consultant of: Roche, Grant/research support from: Roche, Anne Barton: None declared, Timothy Vyse: None declared, Jennifer Barrett: None declared, Edward Vital Consultant of: Roche, Grant/research support from: Roche, Ann Morgan Speakers bureau: Roche/Chugai, Consultant of: GSK, Roche, Chugai, AstraZeneka, Regeneron, Sanofi, Vifor, Grant/research support from: Roche, Kiniksa Pharmaceuticals

Antithyroid drugs in Graves' hyperthyroidism: differences between "block and replace" and "titration" regimes in frequency of euthyroidism and Graves' orbitopathy during treatment

PURPOSE

Whereas antithyroid drugs (ATD) are the preferred treatment modality for Graves' hyperthyroidism (GH), there is still controversy about the optimal regimen for delivering ATD. To evaluate whether 'Block and Replace' (B + R) and 'Titration' (T) regimes are equivalent in terms of frequency of euthyroidism and Graves' Orbitopathy (GO) during ATD therapy.

METHODS

A prospective multicentre observational cohort study of 344 patients with GH but no GO at baseline. Patients were treated with ATD for 18 months according to B + R or T regimen in line with their institution's policy.

RESULTS

Baseline characteristics were similar in both groups. In the treatment period between 6 and 18 months thyrotropin (TSH) slightly increased in both groups, but TSH was on average 0.59 mU/L (95% CI 0.27-0.85) lower in the B + R group at all time points (p = 0.026). Serum free thyroxine (FT4) remained stable during the same interval, with a tendency to higher values in the B + R group. The point-prevalence of euthyroidism (TSH and FT4 within their reference ranges) increased with longer duration of ATD in both groups; it was always higher in the T group than in the B + R group: 48 and 24%, respectively, at 6 months, 81 and 58% at 12 months, and 87 and 63% at 18 months (p < 0.002). There were no significant differences between the B + R and T regimens with respect to the fall in thyrotropin binding inhibiting immunoglobulins (TBII) or thyroid peroxidase antibodies (TPO-Ab). GO developed in 15.9% of all patients: 9.1 and 17.8% in B + R group and T group, respectively, (p = 0.096). GO was mild in 13% and moderate-to-severe in 2%.

CONCLUSION

The prevalence of biochemical euthyroidism during treatment with antithyroid drugs is higher during T compared to B + R regimen. De novo development of GO did not differ significantly between the two regimens, although it tended to be higher in the T group. Whether one regimen is clinically more advantageous than the other remains unclear.

Contamination of domestic groundwater systems by verotoxigenic escherichia coli (VTEC), 2003-2019: A global scoping review

Verocytotoxin-producing E. coli (VTEC) are important agents of diarrhoeal disease in humans globally. As a noted waterborne disease, emphasis has been given to the study VTEC in surface waters, readily susceptible to microbial contamination. Conversely, the status of VTEC in potable groundwater sources, generally regarded as a "safe" drinking-water supply remains largely understudied. As such, this investigation presents the first scoping review seeking to determine the global prevalence of VTEC in groundwater supply sources intended for human consumption. Twenty-three peer-reviewed studies were identified and included for data extraction. Groundwater sample and supply detection rates (estimated 0.6 and 1.3%, respectively) indicate VTEC is infrequently present in domestic groundwater sources. However, where generic (fecal indicator) E. coli are present, the VTEC to E. coli ratio was found to be 9.9%, representing a latent health concern for groundwater consumers. Geographically, extracted data indicates higher VTEC detection rates in urban (5.4%) and peri‑urban (4.9%) environments than in rural areas (0.9%); however, this finding is confounded by the predominance of research studies in lower income regions. Climate trends indicate local environments classified as 'temperate' (14/554; 2.5%) and 'cold' (8/392; 2%) accounted for a majority of supply sources with VTEC present, with similar detection rates encountered among supplies sampled during periods typically characterized by 'high' precipitation (15/649; 2.3%). Proposed prevalence figures may find application in preventive risk-based catchment and groundwater quality management including development of Quantitative Microbial Risk Assessments (QMRA). Notwithstanding, to an extent, a large geographical disparity in available investigations, lack of standardized reporting, and bias in source selection, restrict the transferability of research findings. Overall, the mechanisms responsible for VTEC transport and ingress into groundwater supplies remain ambiguous, representing a critical knowledge gap, and denoting a distinctive lack of integration between hydrogeological and public health research. Key recommendations and guidelines are provided for prospective studies directed at increasingly integrative and multi-disciplinary research.

Case report: Total enterectomy following complete small bowel ischaemia in the post-peritonectomy setting

•

Small bowel resection following total ischaemia is feasible post-peritonectomy.

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VAC dressing and skin grafting was beneficial following wound dehiscence.

•

Small bowel transplant is a potential means to avoid complications of long-term TPN.

Introduction

This report presents the rare case of a patient with complete bowel ischaemia following parastomal hernia, leading to total bowel resection, with consideration of post-operative complications and wound management.

Presentation of case

A 59 year old female was found to have complete small bowel ischaemia on exploratory laparatomy, on a background of recurrent appendiceal adenomucinosis, for which she had received previous peritonectomy, cholecystectomy, total colectomy, and partial small bowel resection. The patient was managed with total enterectomy and post-operative total parenteral nutrition.

Discussion

Total enterectomy represents a significant challenge in the postperitonectomy setting, including consideration of wound management with the empty abdomen, and the potential of small bowel transplant in management.

Conclusion

Resection of the small bowel following total small bowel ischaemia is feasible in the post-peritonectomy setting, given appropriate post-operative care and wound management. However, long-term survival remains challenging, especially without small bowel transplant.

THU0002 SOLVING THE COMPLEX MHC ASSOCIATIONS IN SLE IDENTIFIES SEX-RELATED GENE EFFECTS

Background:

Genome-wide association analyses reveal that the Major Histocompatibility Complex (MHC) is the site of the strongest association signals in SLE and Sjögren’s syndrome. This associations in lupus and Sjögren’s syndrome are linked toHLAalleles: HLA-DRB1*03:01 and HLA-DRB1*15:01 (in Europeans). The DRB1*03:01 allele resides on an extended MHC haplotype which includes loss of the complement C4A gene. Whether C4 makes a genetic contribution to SLE/Sjogren’s risk has been a long standing issue of contention1. In comparison, it has been shown that elevated copy number of C4 is a genetic risk factor for schizophrenia2.

Objectives:

To define the causal MHC genes in SLE/Sjogren’s accommodating both structural and highly polymorphic variation.

Methods:

Use NG sequencing data from across the MHC to generate a panel of variants that inform class III structural variation involving the candidate genes coding complementC4AandC4Bas described2. To further improve the resolution of the association using transancestral mapping approach in SLE: examining cohorts of European ancestry (from ImmunoChip) and data from the MHC region of an African-American GWAS in SLE.

Results:

Comparing European and African data, we have shown that the association signals in SLE can be best explained by signals arising from 1) copy number variation of the complement component 4 (C4) genes in the MHC locus (Fig. 1) and 2) by a shared region in the class II region on the HLA-DRB1*15:01 (in Europeans) and HLA-DRB1*15:03 (in Africans) that likely operates to elevated HLA class II gene expression (Fig. 2). TheC4locus generates a 7-fold variation in risk for lupus (95% CI: 5.88-8.61;p<10-117in total) and 16-fold variation in risk for Sjögren’s syndrome (95% CI: 8.59-30.89;p<10-23in total), withC4Aprotecting more strongly thanC4Bin both illnesses. In schizophrenia, elevated C4 copy number elevates disease risk, whereas in SLE and Sjögren’s lower copy numbers ofC4genes correlate with higher disease risk. In all three illnesses,C4alleles acted more strongly in men than in women: common combinations ofC4AandC4Bgenerated 14-fold variation in risk for lupus and 31-fold variation in risk for Sjögren’s syndrome in men (versus 6-fold and 15-fold among women respectively) and affected schizophrenia risk about twice as strongly in men as in women. At a protein level, both C4 and its effector (C3) were present at greater levels in men than women in cerebrospinal fluid (p<10-5for both C4 and C3) and plasma among adults ages 20-50, corresponding to the ages of differential disease vulnerability. Sex differences in complement protein levels may help explain the larger effects ofC4alleles in men, women’s greater risk of SLE and Sjogren’s, and men’s greater vulnerability in schizophrenia.

Figure 1.

Loss ofC4is risk in African and European ancestry cohorts. A = C4A, B = C4B, A-B = C4A + C4B (L) = Long form (with HERV), (S) = short form

Figure 2.

Common class II association after removing C4 signal

Conclusion:

These results nominate the complement system as a source of sexual dimorphism in vulnerability to diverse illnesses.

References:

[1]Hanscombe KB, Morris DL, Noble JAet al. Hum Mol Genet. 2018; 27(21): 3813-3824.

[2]Sekar A, Bialas AR, de Rivera Het al. Nature.2016; 530(7589): 177-83.

Acknowledgments:

This work was supported by the National Human Genome Research Institute (HG006855), the National Institute of Mental Health (MH112491, MH105641, MH105653), and the Stanley Center for Psychiatric Research. The KCL/GSTT biomedical research centre.

Disclosure of Interests:

Nolan Kamitaki: None declared, Bob Handsaker: None declared, David Morris: None declared, Carl Langefeld: None declared, Robert Graham Employee of: Genentech, Speakers bureau: Genentech, Lindsey Criswell: None declared, Steve McCarroll: None declared, Tim Vyse: None declared

THU0018 GENETIC FACTORS AND RESPONSE TO RITUXIMAB THERAPY IN SLE

Background:

The biologic drug Rituximab (anti-CD20) is used therapeutically in SLE, however the clinical response to the therapy, which is expensive, is quite variable. Factors influencing the efficacy have been challenging to determine. The MRC funded MASTERPLANS consortium has investigated prognostic factors that determine the therapeutic response to biologic therapy in SLE. Genetics has not been studied on a large scale in this context. SLE is a complex clinical phenotype, it is likewise a complex genetic trait, although it has recently been shown that polygenic risk scores do have a relationship to the severity of the disease (1). In addition, genetic risk factors for SLE, coded at the IgG Fc gamma receptor locus, have the potential to influence antibody-dependent cell-mediated cytotoxicity.

Objectives:

To determine whether the genetics influences the clinical outcome of therapy with Rituximab. The study used both genome-wide data in the form of genetic risk scores as well as specific genetic data at a candidate locus, namely the IgG Fc gamma receptor locus

Methods:

Samples from the BILAG Biologics Register (BILAG BR) of individuals treated with Rituximab were subject to genome-wide genotyping with Illumina GSA V2 chip. Genetic risk scores (GRS) were calculated through a weighted risk sum. Genetic variation at the IgG Fc gamma receptor locus is not captured well on genotyping chips and hence common coding and copy number variation was studied using Multiplex Ligation-dependent Probe Amplification (MLPA) and sequencing.

Results:

BILAG-BR samples for SLE part of receiving Rituximab therapy were genotyped on GSA chip, 573 samples passed QC and were used in principal components analysis (PCA), among them, 310 samples both have RTX treatment information and GRS calculated. Examining the population using PCA in the informative samples revealed that the largest distinction, European versus African ancestry did not correlate with Rituximab response. When GRS was determined in the Responders versus the Non-responders there was a weak correlation with those with a higher risk score showing a tendency to be in the responder group (Fig. 1). We also examined variation at the IgG Fc gamma receptor locus, polymorphisms of which are associated with SLE and have been correlated with therapeutic outcome in lymphoma (2). In a subset of the BILAG-BR cohort, we show that carriage of the SLE risk allele atFCGR3A(158F) was enriched in the ‘responder at some point’ group compared to the non-responder group (P=0.03, Chi-square).

Conclusion:

We present preliminary data indicating that genetics at both the genome wide level and at theFCGRlocus show some influence on the outcome of therapy with Rituximab in SLE; more data are required in order to draw firm conclusions.

References:

[1]Reid S et al. High genetic risk score is associated with early disease onset, damage accrual and decreased survival in systemic lupus erythematosus.Ann Rheum Dis.2019 Dec 11. [Epub ahead of print]

[2]Weng WK, Levy R. Two immunoglobulin G fragment C receptor polymorphisms independently predict response to rituximab in patients with follicular lymphoma. J Clin Oncol. 2003;21(21):3940–3947.

Acknowledgments:

King’s and GSTT Biomedical Research Centre and M01665X/1MRC Stratified Medicine grant

Disclosure of Interests:

Lu Liu: None declared, Ariella Amar: None declared, James Robinson: None declared, Ian N. Bruce Grant/research support from: Genzyme Sanofi, GSK, and UCB, Consultant of: Eli Lilly, AstraZeneca, UCB, Iltoo, and Merck Serono, Speakers bureau: UCB, David Morris: None declared, Tim Vyse: None declared

Cryptosporidium spp. in groundwater supplies intended for human consumption - A descriptive review of global prevalence, risk factors and knowledge gaps

Cryptosporidiosis is one of the leading causes of diarrhoeal illness and mortality induced by protozoan pathogens worldwide. As a largely waterborne disease, emphasis has been given to the study of Cryptosporidium spp. in surface waters, readily susceptible to pathogenic contamination. Conversely, the status of Cryptosporidium in potable groundwater sources, generally regarded as a pristine and "safe" drinking-water supply owing to (sub)-soil protection, remains largely unknown. As such, this investigation presents the first literature review aimed to ascertain the global prevalence of Cryptosporidium in groundwater supply sources intended for human consumption. Thirty-seven peer-reviewed studies were identified and included in the review. Groundwater sample and supply detection rates (estimated 10-20%) indicate Cryptosporidium is frequently present in domestic groundwater sources, representing a latent health concern for groundwater consumers. Specifically, sample (10.4%) and source (19.1%) detection rates deriving from comprehensive "temporal" investigations are put forward as representative of a contamination 'baseline' for Cryptosporidium in 'domestic' groundwater supplies. Proposed 'baseline' prevalence figures are largely applicable in preventive risk-based catchment and groundwater quality management including the formulation of Quantitative Microbial Risk Assessment (QMRA). Notwithstanding, a large geographical disparity in available investigations and lack of standardized reporting restrict the transferability of research findings. Overall, the mechanisms responsible for Cryptosporidium transport and ingress into groundwater supplies remain ambiguous, representing a critical knowledge gap, and denoting a distinctive lack of integration between groundwater and public-health sub-disciplines among investigations. Key recommendations and guidelines are provided for prospective studies directed at more integrative and multi-disciplinary research.

Vismodegib for periocular basal cell carcinoma: an international multicentre case series

INTRODUCTION

Vismodegib (Erivedge, Genentech) is a first-in-class inhibitor of the hedgehog (Hh) pathway, which is licensed for use in locally advanced basal cell carcinoma (BCC) and metastatic BCC. The National Institute for Health and Care Excellence withdrew recommendation for use of vismodegib secondary to a lack of data comparing vismodegib to standard supportive care. The purpose of this multicentre, international case series is to report outcomes of patients with locally advanced periocular BCC who have been treated with vismodegib.

METHODS

The medical records of all patients treated with vismodegib were retrospectively reviewed across seven institutions in the United Kingdom, Australia, and New Zealand.

RESULTS

Thirteen patients were identified. Seven (54%) patients were male. All BCCs were ill-defined, with seven (58%) having orbital involvement at presentation. Median treatment time was 7 months (range 2-36 months). Eleven out of 13 patients developed side effects, the most common being fatigue in six patients (46%). Median follow-up was 24 months (range 12-48 months). Complete response was found in 5/13 patients (38%) and a partial response in 8/13 patients (62%). Six patients had further surgery after vismodegib, with three classed as globe-sparing operations. Three patients developed recurrence (23%). Three patients (23%) ultimately underwent exenteration.

DISCUSSION

This study demonstrates vismodegib to be a well-tolerated treatment which may, in some cases, facilitate globe-sparing surgery and hence avoid disfiguring operations such as exenteration. Uncertainty does remain regarding the long-term outcomes of patients treated with vismodegib.

X-linked miR-506 family miRNAs promote FMRP expression in mouse spermatogonia

Comment on "A microRNA cluster in the Fragile-X region expressed during spermatogenesis targets FMR1" by Ramaiah et al.

3076Individual patient meta-analysis of global longitudinal strain: is one normal range enough?

Background

Despite over a decade of evidence, uptake of GLS into guidelines and practice has been slow. Age, BP, and software have been reported to influence GLS, and have led to uncertainty about defining the normal range (NR). As there have been software changes since the last meta-analysis, we sought to define NR in the current era.

Methods

Pubmed, Cochrane, and EMBASE were searched using the keywords “Left Ventricle”, “Normal global longitudinal strain”, and “Speckle tracking Echocardiography” and relevant synonyms from 2011. Studies were included if they reported GLS based on speckle tracking techniques, included at least 20 healthy individuals, and had up to date contact details available. Healthy was defined as lack of known disease. Platforms used included General Electric, Philips, Canon and Tomtec. The authors of 8 of the 12 studies (67% response) provided individual patient data. Linear regression was used to determine predictors of GLS.

Results

There were 2396 pts, mean age 42 years (range 18–92), weight 66±12kg, height 169±9cm, BSA 1.7±0.2m2, and SBP 120±13 mmHg. Normal range for GLS was 21.0±2.6%. In multivariable analysis age (β=-0.02, p<0.01), weight (β=-0.03, p<0.01), SBP (β=-0.01, p<0.01) and platform were associated with GLS. GLS tends to vary with extremes of age and BP (see Figure 1 and Figure 2).

GLS vs Age group

Conclusion

Extremes of age and BP may lead to low GLS, but generally, GLS is <16% is abnormal.

Acknowledgement/Funding

None

A network approach to developing immuno-oncology combinations in Canada

Immune checkpoint inhibitors have revolutionized care for many cancer indications, with considerable effort now being focused on increasing the rate, depth, and duration of patient response. One strategy is to combine immune strategies (for example, ctla-4 and PD-1/L1-directed agents) to harness additive or synergistic efficacy while minimizing toxicity. Despite encouraging results with such combinations in multiple tumour types, numerous clinical challenges remain, including a lack of biomarkers that reliably predict outcome, the emergence of therapeutic resistance, and optimal management of immune-related toxicities. Furthermore, the selection of ideal combinations from the myriad of immune, systemic, and locoregional therapies has yet to be determined. A longitudinal network-based approach could offer advantages in addressing those critical questions, including long-term follow-up of patients beyond individual trials. The molecular cancer registry Personalize My Treatment, managed by the Networks of Centres of Excellence nonprofit organization Exactis Innovation, is uniquely positioned to accelerate Canadian immuno-oncology (io) research efforts throughout its national network of cancer sites. To gain deeper insight into how a pan-Canadian network could advance research in io combinations, Exactis invited preeminent clinical and scientific advisors from across Canada to a roundtable event in November 2017. The present white paper captures the expert advice provided: leverage longitudinal patient data collection; facilitate network collaboration and assay harmonization; synergize with existing initiatives, networks, and biobanks; and develop an io combination trial based on Canadian discoveries.

Activated charcoal as a capture material for silver nanoparticles in environmental water samples

Silver nanoparticles (AgNPs), due to their antibacterial activity, have been incorporated into numerous consumer products. Their environmental impact however, is currently unclear. Uncertainties surround the concentration, fate, and effects of AgNPs in aquatic environments. This study examined the suitability of activated charcoal as a capture material for AgNPs from water. Samples of 100 ppb AgNPs were initially generated and exposed to activated charcoal for 24 h to examine the ability of charcoal to capture AgNPs. The decrease in Ag concentration was measured using ICP-MS. Following initial investigations, the surface area of the charcoal was increased firstly with a pestle and mortar and secondly by milling the charcoal using a ball mill. The increased surface area of the milled charcoal increased the capture of the AgNPs from 11.9% to 63.6% for the 100 ppb samples. Further investigations were carried out examining the effect on the capture of AgNP concentration (with concentration ranging from 10 to 100 ppb), particle coating and the effect of exposure time to the activated charcoal. The capture of AgNP increased with decreasing concentration. A hydrochloric acid (HCl) leaching procedure was also developed which successfully removed the captured silver allowing the fraction captured by the charcoal to be quantified with an average of 94.8% recovery. The results show that milled activated charcoal, can successfully capture AgNPs from water samples, and that therefore, activated charcoal may prove to be a cost effective material for the remediation of waters impacted by AgNP or other nano-wastes.

Cardiac anomaly detection based on time and frequency domain features using tree-based classifiers

OBJECTIVE

Recent advantages in mHealth-enabled ECG recorders boosted the demand for algorithms, which are able to automatically detect cardiac anomalies with high accuracy.

APPROACH

We present a combined method of classical signal analysis and machine learning which has been developed during the Computing in Cardiology Challenge (CinC) 2017. Almost 400 hand-crafted features have been developed to reflect the complex physiology of cardiac arrhythmias and their appearance in single-channel ECG recordings. For the scope of this article, we performed several experiments on the publicly available challenge dataset to improve the classification accuracy. We compared the performance of two tree-based algorithms-gradient boosted trees and random forests-using different parameters for learning. We assessed the influence of five different sets of training annotations on the classifiers performance. Further, we present a new web-based ECG viewer to review and correct the training labels of a signal data set. Moreover, we analysed the feature importance and evaluated the model performance when using only a subset of the features. The primary data source used in the analysis was the dataset of the CinC 2017, consisting of 8528 signals from four classes. Our best results were achieved using a gradient boosted tree model which worked significantly better than random forests.

MAIN RESULTS

Official results of the challenge follow-up phase provided by the Challenge organizers on the full hidden test set are 90.8% (Normal), 84.1% (AF), 74.5% (Other), resulting in a mean F1-score of 83.2%, which was only 1.6% behind the challenge winner and 0.2% ahead of the next-best algorithm. Official results were rounded to two decimal places which lead to the equal-second best F1 _F -score of 83% with five others.

SIGNIFICANCE

The algorithm achieved the second-best score among 80 algorithms of the Challenge follow-up phase equal with five others.

The single-line-of-sight, time-resolved x-ray imager diagnostic on OMEGA

The single-line-of-sight, time-resolved x-ray imager (SLOS-TRXI) on OMEGA is one of a new generation of fast-gated x-ray cameras comprising an electron pulse-dilation imager and a nanosecond-gated, burst-mode, hybrid complementary metal-oxide semiconductor sensor. SLOS-TRXI images the core of imploded cryogenic deuterium-tritium shells in inertial confinement fusion experiments in the ∼4- to 9-keV photon energy range with a pinhole imager onto a photocathode. The diagnostic is mounted on a fixed port almost perpendicular to a 16-channel, framing-camera-based, time-resolved Kirkpatrick-Baez microscope, providing a second time-gated line of sight for hot-spot imaging on OMEGA. SLOS-TRXI achieves ∼40-ps temporal resolution and better than 10-μm spatial resolution. Shots with neutron yields of up to 1 × 10¹⁴ were taken without observed neutron-induced background signal. The implosion images from SLOS-TRXI show the evolution of the stagnating core.

Sub-nanosecond single line-of-sight (SLOS) x-ray imagers (invited)

A new generation of fast-gated x-ray framing cameras have been developed that are capable of capturing multiple frames along a single line-of-sight with 30 ps temporal resolution. The instruments are constructed by integrating pulse-dilation electron imaging with burst mode hybrid-complimentary metal-oxide-semiconductor sensors. Two such instruments have been developed, characterized, and fielded at the National Ignition Facility and the OMEGA laser. These instruments are particularly suited for advanced x-ray imaging applications in Inertial Confinement Fusion and High energy density experiments. Here, we discuss the system architecture and the techniques required for tuning the instruments to achieve optimal performance. Characterization results are also presented along with planned future improvements to the design.

Shiga toxigenic Escherichia coli incidence is related to small area variation in cattle density in a region in Ireland

Shiga toxigenic Escherichia coli (STEC) are pathogenic E. coli that cause infectious diarrhoea. In some cases infection may be complicated by renal failure and death. The incidence of human infection with STEC in Ireland is the highest in Europe. The objective of the study was to examine the spatial incidence of human STEC infection in a region of Ireland with significantly higher rates of STEC incidence than the national average and to identify possible risk factors of STEC incidence at area level. Anonymised laboratory records (n = 379) from 2009 to 2015 were obtained from laboratories serving three counties in the West of Ireland. Data included location and sample date. Population and electoral division (ED) data were obtained from the Irish 2011 Census of Population. STEC incidence was calculated for each ED (n = 498) and used to map hotspots/coldspots using the Getis-Ord Gi* spatial statistic and significant spatial clustering using the Anselin's Local Moran's I statistic. Multivariable regression analysis was used to consider the importance of a number of potential predictors of STEC incidence. Incidence rates for the seven-year period ranged from 0 to 10.9 cases per 1000. A number of areas with significant local clustering of STEC incidence as well as variation in the spatial distribution of the two main serogroups associated with disease in the region i.e. O26 and O157 were identified. Cattle density was found to be a statistically significant predictor of STEC in the region. GIS analysis of routine data indicates that cattle density is associated STEC infection in this high incidence region. This finding points to the importance of agricultural practices for human health and the importance of a "one-health" approach to public policy in relation to agriculture, health and environment.

The Doctor Can See You Now: A Key Stakeholder Study Into The Acceptability Of Ambulance Based Telemedicine

Using telecommunications technology it would be possible to link a patient and paramedic to a Doctor in the Emergency Department (ED) at the point of first patient contact. A questionnaire-based study on telemedicine in the pre-hospital environment involving patients, paramedics, doctors and nurses in the ED, was performed to assess if they would want and accept telemedicine in pre-hospital emergency care. When asked 98.5% (55) of patients, 89% (11) of doctors, 76% (14) of nurses and 91% (42) of ambulance personnel saw the potential of an audio-visual link from the pre-hospital environment to the ED. The potential benefits were felt to be in diagnosis of time-dependent illnesses, time management, increased hospital preparedness for incoming patients and increased triage efficiency. Stakeholder enthusiasm for pre-hospital telemedicine must be met with the technological requirements to provide such a service. As noted by one patient a pre-hospital audio-visual link to the ED could be “potentially a life saving service”.

Reasons for lack of referral to medical oncology for systemic therapy in stage IV non-small-cell lung cancer: comparison of 2003-2006 with 2010-2011

Introduction

Only approximately 25% of stage iv non-small-cell lung cancer (nsclc) patients receive systemic therapy. For such patients, we examined factors affecting referral to a cancer centre (cc) and to medical oncology (mo), and use of systemic therapy.

Methods

Using the Glans-Look Lung Cancer database, we completed a chart review of stage iv nsclc patients diagnosed in Southern Alberta during 2003-2006 and 2010-2011, comparing median overall survival (mos), referral, and treatment in the two cohorts.

Results

Of the 922 patients diagnosed in 2003-2006 and the 560 diagnosed in 2010-2011, 94% and 82% respectively were referred to a cc, with 22% and 23% receiving traditional chemotherapy (tctx). Referral to a cc or mo and use of tctx correlated with survival (p < 0.0001): The mos duration was 11.2 months in those receiving tctx and 1.0 months in those not referred to a cc. The overall mos duration was similar in the two cohorts (4.1 months vs. 3.9 months, p = 0.47). Major reasons for lack of referral to mo included poor functional status, rapid decline, and patient wish, which were similar to the reasons for forgoing tctx. In the two cohorts, 87 (9.4%) and 42 (7.5%) patients received epidermal growth factor inhibitors, with a mos duration of 16.2 months. Multivariable analysis showed that male sex [hazard ratio (hr): 1.16; p = 0.008] and pulmonary embolus (hr: 1.2; p = 0.002) correlated with worse survival. In contrast, receipt of chemotherapy (hr: 0.5; p < 0.001) and enrolment in a clinical trial (hr: 0.76; p = 0.049) correlated with better survival.

Conclusions

Our experience confirms that, over time, uptake of systemic therapy, including tctx and targeted therapy, changed little despite their established efficacy. Most of the factors limiting systemic therapy uptake appear to be non-modifiable at the time of referral. Rapid diagnosis and the availability of well-tolerated drugs for all nsclc patients will likely be the most important factors in increasing systemic therapy uptake in this population.

Pathologists’ Views on Consent for Autopsy

Consent to autopsy is usually obtained by a doctor other than the one who will perform the procedure. There is an argument that, for proper informed consent, a pathologist should participate. We ascertained the views of consultant pathologists in south-east England.

53 (87%) of 61 consultants responded, of whom 50 currently do autopsies. Only 2 at present participate directly in obtaining consent, and 10 of the remaining 48 expressed willingness to do so. The general view was that consent is best obtained by a senior clinician from the team that has looked after the patient.

Pathologists see their primary role as to provide guidance to clinicians. Few see it as their function to obtain consent for autopsy.

GWAS meta-analysis reveals novel loci and genetic correlates for general cognitive function: a report from the COGENT consortium

This corrects the article DOI: 10.1038/mp.2016.244.

Prevalence of Methicillin-Resistant Staphylococcus aureus from Equine Nasopharyngeal and Guttural Pouch Wash Samples

BACKGROUND

Methicillin-resistant Staphylococcus aureus (MRSA) is recognized as a cause of nosocomial infections in both human and veterinary medicine. Studies that examine the nasopharynx and guttural pouches of the horse as carriage sites for MRSA have not been reported.

HYPOTHESIS/OBJECTIVE

MRSA colonizes the nasopharynx and guttural pouch of horses. To determine the prevalence of MRSA in equine nasopharyngeal wash (NPW) and guttural pouch lavage (GPL) samples in a field population of horses.

SAMPLES

One hundred seventy-eight samples (123 NPW and 55 GPL) from 108 horses.

METHODS

Prospective study. Samples were collected from a convenience population of clinically ill horses with suspected Streptococcus equi subsp. equi (S. equi) infection, horses convalescing from a known S. equi infection, and asymptomatic horses undergoing S. equi screening. Samples were submitted for S. aureus aerobic bacterial culture with mannitol salt broth and two selective agars (cefoxitin CHROMagar as the PBP2a inducer and mannitol salt agar with oxacillin). Biochemical identification of Staphylococcus species and pulsed-field gel electrophoresis (PFGE), to determine clonal relationships between isolates, were performed.

RESULTS

Methicillin-resistant Staphylococcus (MRS) was isolated from the nasopharynx of 7/108 (4%) horses. Three horses had MRSA (2.7%), and 4 had MR-Staphylococcus pseudintermedius (MRSP). MRSA was isolated from horses on the same farm. PFGE revealed the 3 MRSA as USA 500 strains.

CONCLUSIONS AND CLINICAL IMPORTANCE

Sampling the nasopharynx and guttural pouch of community-based horses revealed a similarly low prevalence rate of MRSA as other studies sampling the nares of community-based horses. More study is required to determine the need for sampling multiple anatomic sites when screening horses for MRSA.

Rare DNA variants in the brain-derived neurotrophic factor gene increase risk for attention-deficit hyperactivity disorder: a next-generation sequencing study

Attention-deficit hyperactivity disorder (ADHD) is a prevalent and highly heritable disorder of childhood with negative lifetime outcomes. Although candidate gene and genome-wide association studies have identified promising common variant signals, these explain only a fraction of the heritability of ADHD. The observation that rare structural variants confer substantial risk to psychiatric disorders suggests that rare variants might explain a portion of the missing heritability for ADHD. Here we believe we performed the first large-scale next-generation targeted sequencing study of ADHD in 152 child and adolescent cases and 188 controls across an a priori set of 117 genes. A multi-marker gene-level analysis of rare (<1% frequency) single-nucleotide variants (SNVs) revealed that the gene encoding brain-derived neurotrophic factor (BDNF) was associated with ADHD at Bonferroni corrected levels. Sanger sequencing confirmed the existence of all novel rare BDNF variants. Our results implicate BDNF as a genetic risk factor for ADHD, potentially by virtue of its critical role in neurodevelopment and synaptic plasticity.