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A genetic contribution to psychiatric disorders has clearly been established and genome‐wide association studies now provide the location of risk genes and genetic variants associated with risk. However, the mechanism by which these genes and variants contribute to psychiatric disorders is mostly undetermined. This is in part because non‐synonymous protein coding changes cannot explain the majority of variants associated with complex genetic traits. Based on this, it is predicted that these variants are causing gene expression changes, including changes to alternative splicing. Genetic changes influencing alternative splicing have been identified as risk factors in Mendelian disorders; however, currently there is a paucity of research on the role of alternative splicing in complex traits. This stems partly from the difficulty of predicting the role of genetic variation in splicing. Alterations to canonical splice site sequences, nucleotides adjacent to splice junctions, and exonic and intronic splicing regulatory sequences can influence splice site choice. Recent studies have identified global changes in alternatively spliced transcripts in brain tissues, some of which correlate with altered levels of splicing trans factors. Disease‐associated variants have also been found to affect cis‐acting splicing regulatory sequences and alter the ratio of alternatively spliced transcripts. These findings are reviewed here, as well as the current datasets and resources available to study alternative splicing in psychiatric disorders. Identifying and understanding risk variants that cause alternative splicing is critical to understanding the mechanisms of risk as well as to pave the way for new therapeutic options. [ABSTRACT FROM AUTHOR]

Introduction: Hereditary cancer syndromes (HCS), such as Hereditary Breast and Ovarian Cancer Syndrome (HBOC) and Lynch Syndrome (LS), represent approximately 10% of all cancers. Along with medical burdens associated with the genetic risk of developing cancer, many individuals face stigma and discrimination. Genetic discrimination refers to negative treatment, unfair profiling or harm based on genetic characteristics, manifesting as "felt" stigma (ostracization without discriminatory acts) or "enacted" stigma (experiencing discriminatory acts). This study aimed to describe concerns and experiences of genetic discrimination faced by individuals with HCS., Methods: Semi-structured qualitative interviews were conducted with individuals with molecularly-confirmed HCS residing in Ontario, British Columbia and Newfoundland & Labrador, Canada. Purposive sampling was applied to obtain a diverse sample across demographic characteristics. Study procedures were informed by interpretive description; data were thematically analyzed using constant comparison., Results: 73 participants were interviewed (39 HBOC, 34 LS; 51 females, 21 males, 1 gender-diverse; aged 25-80). Participants described multifaceted forms of genetic discrimination across healthcare, insurance, employment, and family/social settings. Participants valued the Genetic Non-Discrimination Act's protective intent, but demonstrated limited knowledge of its existence and provisions. Limited knowledge, coupled with policy constraints in non-legislatable settings and third-party use of proxy genetic information, hindered participants' ability to whistleblow or seek recourse., Conclusion: Our results illuminate a disconnect between intended protective effects of genetic non-discrimination legislation and ongoing genetic discrimination faced by individuals with hereditary conditions. To better support these individuals, this study encourages public outreach and knowledge translation efforts to increase awareness of non-discrimination legal protections., (The Author(s). Published by S. Karger AG, Basel.)

Introduction: Genetic testing is used across medical disciplines leading to unprecedented demand for genetic services. This has resulted in excessive waitlists and unsustainable pressure on the standard model of genetic healthcare. Alternative models are needed; e-health tools represent scalable and evidence-based solution. We aim to evaluate the effectiveness of the Genetics Navigator, an interactive patient-centred digital platform that supports the collection of medical and family history, provision of pregenetic and postgenetic counselling and return of genetic testing results across paediatric and adult settings., Methods and Analysis: We will evaluate the effectiveness of the Genetics Navigator combined with usual care by a genetics clinician (physician or counsellor) to usual care alone in a randomised controlled trial. One hundred and thirty participants (adults patients or parents of paediatric patients) eligible for genetic testing through standard of care will be recruited across Ontario genetics clinics. Participants randomised into the intervention arm will use the Genetics Navigator for pretest and post-test genetic counselling and results disclosure in conjunction with their clinician. Participants randomised into the control arm will receive usual care, that is, clinician-delivered pretest and post-test genetic counselling, and results disclosure. The primary outcome is participant distress 2 weeks after test results disclosure. Secondary outcomes include knowledge, decisional conflict, anxiety, empowerment, quality of life, satisfaction, acceptability, digital health literacy and health resource use. Quantitative data will be analysed using statistical hypothesis tests and regression models. A subset of participants will be interviewed to explore user experience; data will be analysed using interpretive description. A cost-effectiveness analysis will examine the incremental cost of the Navigator compared with usual care per unit reduction in distress or unit improvement in quality of life from public payer and societal perspectives., Ethics and Dissemination: This study was approved by Clinical Trials Ontario. Results will be shared through stakeholder workshops, national and international conferences and peer-reviewed journals., Trial Registration Number: NCT06455384., Competing Interests: Competing interests: YB and MC are cofounders of Genetics Adviser., (© Author(s) (or their employer(s)) 2024. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Hereditary cancer syndromes (HCS) predispose individuals to a higher risk of developing multiple cancers. However, current screening strategies have limited ability to screen for all cancer risks. Circulating tumour DNA (ctDNA) detects DNA fragments shed by tumour cells in the bloodstream and can potentially detect cancers early. This study aimed to explore patients' perspectives on ctDNA's utility to help inform its clinical adoption and implementation. We conducted a qualitative interpretive description study using semi-structured phone interviews. Participants were purposively sampled adult HCS patients recruited from a Canadian HCS research consortium. Thirty HCS patients were interviewed (n = 19 women, age range 20s-70s, n = 25 were white). Participants were highly concerned about developing cancers, particularly those without reliable screening options for early detection. They "just wanted more" than their current screening strategies. Participants were enthusiastic about ctDNA's potential to be comprehensive (detect multiple cancers), predictive (detect cancers early) and tailored (lead to personalized clinical management). Participants also acknowledged ctDNA's potential limitations, including false positives/negatives risks and experiencing additional anxiety. However, they saw ctDNA's potential benefits outweighing its limitations. In conclusion, participants' belief in ctDNA's potential to improve their care overshadowed its limitations, indicating patients' support for using ctDNA in HCS care., (© 2023. The Author(s), under exclusive licence to European Society of Human Genetics.)

Purpose: We sought to explore patient-reported utility of all types of cancer results from genomic sequencing (GS)., Methods: Qualitative study, using semi-structured interviews with patients who underwent GS within a trial. Thematic analysis employing constant comparison was used. Two coders coded transcripts, with use of a third coder to resolve conflicts., Results: 25 patients participated: female (22), >50 years (18), European (12), Ashkenazi Jewish (5), Middle Eastern (3), or other ethnicity (5), with breast cancer history (20). Patients' perceptions of the utility of cancer GS results hinged on whether they triggered clinical action. For example, when patients were enrolled into high-risk breast cancer surveillance programs for low/moderate risk breast cancer genes, they perceived the results to be very "useful" and of moderate-high utility. In contrast, patients receiving low/moderate risk or primary variants of uncertain significance results without clinical action perceived results as "concerning," leading to harms, such as hypervigilance about cancer symptoms. Overall, having supportive relatives or providers enhanced perceptions of utility., Conclusion: Patients' perceptions of cancer GS results hinged on whether they triggered clinical management. Consequently, patients who received results without clinical action became hypervigilant, experiencing harms. Our findings call for a need to develop practice interventions to support patients with cancer undergoing GS., Competing Interests: Conflict of Interest The authors declare no conflicts of interest., (Copyright © 2023 American College of Medical Genetics and Genomics. Published by Elsevier Inc. All rights reserved.)

Secondary findings (SFs) identified through genomic sequencing (GS) can offer a wide range of health benefits to patients. Resource and capacity constraints pose a challenge to their clinical management; therefore, clinical workflows are needed to optimise the health benefits of SFs. In this paper, we describe a model we created for the return and referral of all clinically significant SFs, beyond medically actionable results, from GS. As part of a randomised controlled trial evaluating the outcomes and costs of disclosing all clinically significant SFs from GS, we consulted genetics and primary care experts to determine a feasible workflow to manage SFs. Consensus was sought to determine appropriate clinical recommendations for each category of SF and which clinician specialist would provide follow-up care. We developed a communication and referral plan for each category of SFs. This involved referrals to specialised clinics, such as an Adult Genetics clinic, for highly penetrant medically actionable findings. Common and non-urgent SFs, such as pharmacogenomics and carrier status results for non-family planning participants, were directed back to the family physician (FP). SF results and recommendations were communicated directly to participants to respect autonomy and to their FPs to support follow-up of SFs. We describe a model for the return and referral of all clinically significant SFs to facilitate the utility of GS and promote the health benefits of SFs. This may serve as a model for others returning GS results transitioning participants from research to clinical settings., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2023. No commercial re-use. See rights and permissions. Published by BMJ.)

Genomic sequencing (GS) can reveal secondary findings (SFs), findings unrelated to the reason for testing, that can be overwhelming to both patients and providers. An effective approach for communicating all clinically significant primary and secondary GS results is needed to effectively manage this large volume of results. The aim of this study was to develop a comprehensive approach to communicate all clinically significant primary and SF results. A genomic test report with accompanying patient and provider letters were developed in three phases: review of current clinical reporting practices, consulting with genetic and non-genetics experts, and iterative refinement through circulation to key stakeholders. The genomic test report and consultation letters present a myriad of clinically relevant GS results in distinct, tabulated sections, including primary (cancer) and secondary findings, with in-depth details of each finding generated from exome sequencing. They provide detailed variant and disease information, personal and familial risk assessments, clinical management details, and additional resources to help support providers and patients with implementing healthcare recommendations related to their GS results. The report and consultation letters represent a comprehensive approach to communicate all clinically significant SFs to patients and providers, facilitating clinical management of GS results., (© 2022. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Purpose: Neurodevelopmental disorders (NDDs), such as intellectual disability (ID) and autism spectrum disorder (ASD), exhibit genetic and phenotypic heterogeneity, making them difficult to differentiate without a molecular diagnosis. The Clinical Genome Resource Intellectual Disability/Autism Gene Curation Expert Panel (GCEP) uses systematic curation to distinguish ID/ASD genes that are appropriate for clinical testing (ie, with substantial evidence supporting their relationship to disease) from those that are not., Methods: Using the Clinical Genome Resource gene-disease validity curation framework, the ID/Autism GCEP classified genes frequently included on clinical ID/ASD testing panels as Definitive, Strong, Moderate, Limited, Disputed, Refuted, or No Known Disease Relationship., Results: As of September 2021, 156 gene-disease pairs have been evaluated. Although most (75%) were determined to have definitive roles in NDDs, 22 (14%) genes evaluated had either Limited or Disputed evidence. Such genes are currently not recommended for use in clinical testing owing to the limited ability to assess the effect of identified variants., Conclusion: Our understanding of gene-disease relationships evolves over time; new relationships are discovered and previously-held conclusions may be questioned. Without periodic re-examination, inaccurate gene-disease claims may be perpetuated. The ID/Autism GCEP will continue to evaluate these claims to improve diagnosis and clinical care for NDDs., Competing Interests: Conflict of Interest A.Br. is a shareholder of and employed by Natera. A.Br. has also been an employee of Invitae and Quest Diagnostics commercial laboratories. A.R.C. and K.B. are shareholders of and employed by Illumina, Inc. A.Be. is a shareholder of and is employed by Invitae. B.B. has received research support from Biomarin Pharmaceuticals Inc. He is currently employed by and is a shareholder of Alnylam Pharmaceuticals, Inc. All other authors declare no conflicts of interest., (Copyright © 2022 American College of Medical Genetics and Genomics. Published by Elsevier Inc. All rights reserved.)

Purpose: Emerging genetic tests such as genomic sequencing (GS) can generate a broad range of benefits, but funding criteria only prioritize diagnosis and clinical management. There is limited evidence on all types of benefits obtained from GS in practice. We aimed to explore real-world experiences of Canadian clinicians across specialties on the full range of benefits obtained from the results from GS., Methods: We conducted a qualitative study using semistructured interviews with Canadian clinicians. Transcripts were thematically analyzed using constant comparison., Results: In total, 25 clinicians participated, including 12 geneticists, 7 genetic counselors, 4 oncologists, 1 neurologist, and 1 family physician. Although diagnoses and management were the most valued benefits of GS, clinicians also prioritized nontraditional utility, such as access to community supports. However, clinicians felt "restricted" by funding bodies, which only approved funding when GS would inform diagnoses and management. Consequently, clinicians sought ways to "cheat the system" to access GS (eg, research testing) but acknowledged workarounds were burdensome, drove inequity, and undermined patient care., Conclusion: Current governance structures undervalue real-world benefits of GS leading clinicians to adopt workarounds, which jeopardize patient care. These results support calls for the expansion of the definition of clinical utility and research to quantify the additional benefits., Competing Interests: Conflict of Interest The authors declare no conflicts of interest., (Copyright © 2022 American College of Medical Genetics and Genomics. Published by Elsevier Inc. All rights reserved.)

Most secondary genomic findings (SFs) fall in the scope of primary care practice. However, primary care providers' (PCPs) capacity to manage these findings is not well understood. We explored PCPs' views and experiences of managing SFs through a qualitative study. PCPs participated in semi-structured interviews about SFs from a patient in their practice or a hypothetical patient. The interpretive descriptive methodology was used to analyze transcripts thematically through constant comparison. Fifteen family physicians from Ontario, Canada participated (ten females; 6-40 years in practice across community and academic settings). PCPs made sense of SFs through the lens of actionability: they actively looked for clinical relevance by considering a wide range of immediate and future actions, including referrals, genetic testing, screening, lifestyle changes, counseling about family planning, informing family members, future medication choice, increased vigilance/surveillance, and managing results in the electronic medical record. PCPs saw clinical actionability as the main benefit mitigating the potential harms of learning SFs, namely patient anxiety and unnecessary investigations. PCPs conceptualized actionability more broadly than it is traditionally defined in medical genetics. Further research will be needed to determine if PCPs' emphasis on actionability conflicts with patients' expectations of SFs and if it leads to overutilization of healthcare resources., (© 2021. The Author(s), under exclusive licence to European Society of Human Genetics.)

Introduction: The high demand for genetic tests and limited supply of genetics professionals has created a need for alternative service delivery models. Digital tools are increasingly being used to support multiple points in the genetic testing journey; however, none are transferable across multiple clinical specialties and settings nor do they encompass the entire trajectory of the journey. We aim to evaluate the effectiveness of the Genetics Adviser, an interactive, patient-facing, online digital health tool that delivers pre-test counselling, provides support during the waiting period for results, and returns results with post-test counselling, encompassing the entire patient genetic testing journey., Methods and Analysis: We will compare the Genetics Adviser paired with a brief genetic counselling session to genetic counselling alone in a randomised controlled trial. One hundred and forty patients who previously received uninformative genetic test results for their personal and family history of cancer will be recruited from familial cancer clinics in Toronto and offered all clinically significant results from genomic sequencing. Participants randomised into the intervention arm will use the Genetics Adviser to learn about genomic sequencing, receive pre-test counselling, support during the waiting period and results, supplemented with brief counselling from a genetic counsellor. Participants in the control arm will receive standard pre-test and post-test counselling for genomic sequencing from a genetic counsellor. Our primary outcome is decisional conflict following pre-test counselling from the Genetics Adviser+genetic counsellor or counsellor alone. Secondary outcomes include: knowledge, satisfaction with decision-making, anxiety, quality of life, psychological impact of results, empowerment, acceptability and economic impact for patients and the health system. A subset of patients will be interviewed to assess user experience., Ethics and Dissemination: This study has been approved by Clinical Trials Ontario Streamlined Research Ethics Review System (REB#20-035). Results will be shared through stakeholder workshops, national and international conferences and peer-reviewed journals., Trial Registration Number: NCT04725565., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2022. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Primary care providers will increasingly be tasked with managing most secondary findings from genomic sequencing, but literature exploring their capacity to manage findings beyond conventional genetic testing is limited. This study aimed to explore primary care providers' challenges and potential solutions for managing secondary findings. Providers were recruited in two groups. Group 1 providers had a patient in their practice who received secondary findings and all potential group 1 providers were invited to participate. Group 2 providers were provided with the secondary findings of a hypothetical patient and were purposefully sampled for maximal variation in sex, practice setting, and geographic location. Providers were interviewed about their challenges and solutions managing secondary findings from a patient in their practice or a hypothetical patient. Using interpretive description methodology, transcripts were analysed thematically complemented by constant comparison. Out of the fifty-five providers invited, 15 family physicians participated across community and academic settings in Ontario, Canada (range 6-40 years in practice; 10/15 female). Providers described a responsibility to manage secondary findings, but limited capacity for this, describing practice, knowledge, and technical challenges. Providers expressed concern that compared to other incidental findings, secondary genomic findings might be reported directly to patients and result in longer-term anxiety. Potential solutions were a structured letter with categorized results and summary tables highlighting key secondary findings with follow-up recommendations and resources, as well as electronic medical records (EMRs) that store and integrate genomic information for prescribing or referrals. These solutions were deemed essential to address knowledge and technical challenges faced by primary care physicians and ultimately promote clinical utility of secondary findings., (Copyright © 2021 Elsevier Masson SAS. All rights reserved.)

Background: Exome and genome sequencing have been demonstrated to increase diagnostic yield in paediatric populations, improving treatment options and providing risk information for relatives. There are limited studies examining the clinical utility of these tests in adults, who currently have limited access to this technology., Methods: Patients from adult and cancer genetics clinics across Toronto, Ontario, Canada were recruited into a prospective cohort study evaluating the diagnostic utility of exome and genome sequencing in adults. Eligible patients were ≥18 years of age and suspected of having a hereditary disorder but had received previous uninformative genetic test results. In total, we examined the diagnostic utility of exome and genome sequencing in 47 probands and 34 of their relatives who consented to participate and underwent exome or genome sequencing., Results: Overall, 17% (8/47) of probands had a pathogenic or likely pathogenic variant identified in a gene associated with their primary indication for testing. The diagnostic yield for patients with a cancer history was similar to the yield for patients with a non-cancer history (4/18 (22%) vs 4/29 (14%)). An additional 24 probands (51%) had an inconclusive result. Secondary findings were identified in 10 patients (21%); three had medically actionable results., Conclusions: This study lends evidence to the diagnostic utility of exome or genome sequencing in an undiagnosed adult population. The significant increase in diagnostic yield warrants the use of this technology. The identification and communication of secondary findings may provide added value when using this testing modality as a first-line test., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2021. No commercial re-use. See rights and permissions. Published by BMJ.)

Genomic sequencing advances have increased the potential to identify secondary findings (SFs). Current guidelines recommend the analysis of 59 medically actionable genes; however, patient preferences indicate interest in learning a broader group of SFs. We aimed to develop an analytical pipeline for the efficient analysis and return of all clinically significant SFs. We developed a pipeline consisting of comprehensive gene lists for five categories of SFs and filtration parameters for prioritization of variants in each category. We applied the pipeline to 42 exomes to assess feasibility and efficiency. Comprehensive lists of clinically significant SF genes were curated for each category: (1) 90 medically actionable genes and 28 pharmacogenomic variants; (2) 17 common disease risk variants; (3) 3166 Mendelian disease genes, (4) 7 early onset neurodegenerative disorder genes; (5) 688 carrier status results. Analysis of 42 exomes using our pipeline resulted in a significant decrease (> 98%) in variants compared to the raw analysis (13,036.56 ± 59.72 raw variants/exome vs 161.32 ± 7.68 filtered variants/exome), and aided in time and costs savings for the overall analysis process. Our pipeline represents a critical step in overcoming the analytic challenge associated with returning all clinically relevant SFs to allow for its routine implementation in clinical practice.

The retinitis pigmentosa GTPase regulator interacting protein 1-like ( RPGRIP1L ) gene encodes a ciliary protein that is critical for processes related to brain development, including development of left-right asymmetry, sonic hedgehog signaling, and neural tube formation. RPGRIP1L is a risk factor for retinal degeneration, and rare, deleterious variants in the RPGRIP1L gene cause Joubert syndrome and Meckel syndrome, both autosomal recessive disorders. These syndromes are characterized by dysfunctional primary cilia that result in abnormal development - and even lethality in the case of Meckel syndrome. Genetic studies have also implicated RPGRIP1L in psychiatric disorders by suggestive findings from genome-wide association studies and findings from rare-variant exome analyses for bipolar disorder and de novo mutations in autism. In this study we identify a common variant in RPGRIP1L , rs7203525, that influences alternative splicing, increasing the inclusion of exon 20 of RPGRIP1L . We detected this alternative splicing association in human postmortem brain tissue samples and, using a minigene assay combined with in vitro mutagenesis, confirmed that the alternative splicing is attributable to the alleles of this variant. The predominate RPGRIP1L isoform expressed in adult brains does not contain exon 20; thus, a shift to include this exon may impact brain function., Competing Interests: The authors declare no conflicts of interest., (Copyright © 2019 by S. Karger AG, Basel.)

Introduction: Genomic sequencing has rapidly transitioned into clinical practice, improving diagnosis and treatment options for patients with hereditary disorders. However, large-scale implementation of genomic sequencing faces challenges, especially with regard to the return of incidental results, which refer to genetic variants uncovered during testing that are unrelated to the primary disease under investigation, but of potential clinical significance. High-quality evidence evaluating health outcomes and costs of receiving incidental results is critical for the adoption of genomic sequencing into clinical care and to understand the unintended consequences of adoption of genomic sequencing. We aim to evaluate the health outcomes and costs of receiving incidental results for patients undergoing genomic sequencing., Methods and Analysis: We will compare health outcomes and costs of receiving, versus not receiving, incidental results for adult patients with cancer undergoing genomic sequencing in a mixed-methods randomised controlled trial. Two hundred and sixty patients who have previously undergone first or second-tier genetic testing for cancer and received uninformative results will be recruited from familial cancer clinics in Toronto, Ontario. Participants in both arms will receive cancer-related results. Participants in the intervention arm have the option to receive incidental results. Our primary outcome is psychological distress at 2 weeks following return of results. Secondary outcomes include behavioural consequences, clinical and personal utility assessed over the 12 months after results are returned and health service use and costs at 12 months and 5 years. A subset of participants and providers will complete qualitative interviews about utility of incidental results., Ethics and Dissemination: This study has been approved by Clinical Trials Ontario Streamlined Research Ethics Review System that provides ethical review and oversight for multiple sites participating in the same clinical trial in Ontario.Results from the trial will be shared through stakeholder workshops, national and international conferences, and peer-reviewed journals., Trial Registration Number: NCT03597165., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2019. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Objectives: Monozygotic twins with near-identical genotypes and discordance for complex diseases represent an exceptional resource to ascertain disease etiology. This strategy has been particularly effective with the availability of high-resolution complete individual genome sequencing. The challenge is using effective approaches to identify relevant differences that may cause or contribute toward disease discordance., Participants and Methods: This study carried out a VarScan2 bioinformatic analysis and a pathway analysis on whole-genome sequences from two sets of monozygotic twins., Results: Variants were identified that were present in the affected twin, but not found in the unaffected twin. Such variations are expected to be de novo and originate during the independent development of the twins and may make them discordant for the disease. The genes and de novo variants identified in this experiment are compatible with their involvement in schizophrenia. Further analysis of the variants identified pathways including glutamate receptor signaling that have been implicated in this neurodevelopmental disease., Conclusion: The results support the polygenic nature of schizophrenia and the threshold model for its development. The results also show the effectiveness of VarScan2 to identify 'the needle in the hay stack' that may cause schizophrenia, specifically in the two patients. It offers a proof of principle for assessment of the genetic etiology of complex disorders where discordance of monozygotic twins is an established phenomenon.

Background: Phenotypic overlap among the inherited bone marrow failure syndromes (IBMFSs) frequently limits the ability to establish a diagnosis based solely on clinical features. >70 IBMFS genes have been identified, which often renders genetic testing prolonged and costly. Since correct diagnosis, treatment and cancer surveillance often depend on identifying the mutated gene, strategies that enable timely genotyping are essential., Methods: To overcome these challenges, we developed a next-generation sequencing assay to analyse a panel of 72 known IBMFS genes. Cases fulfilling the clinical diagnostic criteria of an IBMFS but without identified causal genotypes were included., Results: The assay was validated by detecting 52 variants previously found by Sanger sequencing. A total of 158 patients with unknown mutations were studied. Of 75 patients with known IBMFS categories (eg, Fanconi anaemia), 59% had causal mutations. Among 83 patients with unclassified IBMFSs, we found causal mutations and established the diagnosis in 18% of the patients. The assay detected mutant genes that had not previously been reported to be associated with the patient phenotypes. In other cases, the assay led to amendments of diagnoses. In 20% of genotype cases, the results indicated a cancer surveillance programme., Conclusions: The novel assay is efficient, accurate and has a major impact on patient care., (Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.)