Whole-exome sequencing reanalysis at 12 months boosts diagnosis and is cost-effective when applied early in Mendelian disorders

PurposeWhole-exome sequencing (WES) has revolutionized Mendelian diagnostics, however, there is no consensus on the timing of data review in undiagnosed individuals and only preliminary data on the cost-effectiveness of this technology. We aimed to assess the utility of WES data reanalysis for diagnosis in Mendelian disorders and to analyze the cost-effectiveness of this technology compared with a traditional diagnostic pathway.MethodsWES was applied to a cohort of 54 patients from 37 families with a variety of Mendelian disorders to identify the genetic etiology. Reanalysis was performed after 12 months with an improved WES diagnostic pipeline. A comparison was made between costs of a modeled WES pathway and a traditional diagnostic pathway in a cohort with intellectual disability (ID).ResultsReanalysis of WES data at 12 months improved diagnostic success from 30 to 41% due to interim publication of disease genes, expanded phenotype data from referrer, and an improved bioinformatics pipeline. Cost analysis on the ID cohort showed average cost savings of US$586 (AU$782) for each additional diagnosis.ConclusionEarly application of WES in Mendelian disorders is cost-effective and reanalysis of an undiagnosed individual at a 12-month time point increases total diagnoses by 11%.     

Diagnostic odyssey in severe neurodevelopmental disorders: toward clinical whole‐exome sequencing as a first‐line diagnostic test

The current standard of care for diagnosis of severe intellectual disability (ID) and epileptic encephalopathy (EE) results in a diagnostic yield of ～50%. Affected individuals nonetheless undergo multiple clinical evaluations and low‐yield laboratory tests often referred to as a ‘diagnostic odyssey’. This study was aimed at assessing the utility of clinical whole‐exome sequencing (WES) in individuals with undiagnosed and severe forms of ID and EE, and the feasibility of its implementation in routine practice by a small regional genetic center. We performed WES in a cohort of 43 unrelated individuals with undiagnosed ID and/or EE. All individuals had undergone multiple clinical evaluations and diagnostic tests over the years, with no definitive diagnosis. Sequencing data analysis and interpretation were carried out at the local molecular genetics laboratory. The diagnostic rate of WES reached 32.5% (14 out of 43 individuals). Genetic diagnosis had a direct impact on clinical management in four families, including a prenatal diagnostic test in one family. Our data emphasize the clinical utility and feasibility of WES in individuals with undiagnosed forms of ID and EE and highlight the necessity of close collaborations between ordering physicians, molecular geneticists, bioinformaticians and researchers for accurate data interpretation.     

Reducing diagnostic turnaround times of exome sequencing for families requiring timely diagnoses

Background and objectiveWhole-exome sequencing (WES) has now entered medical practice with powerful applications in the diagnosis of rare Mendelian disorders. Although the usefulness and cost-effectiveness of WES have been widely demonstrated, it is essential to reduce the diagnostic turnaround time to make WES a first-line procedure. Since 2011, the automation of laboratory procedures and advances in sequencing chemistry have made it possible to carry out diagnostic whole genome sequencing from the blood sample to molecular diagnosis of suspected genetic disorders within 50 h. Taking advantage of these advances, the main objective of the study was to improve turnaround times for sequencing results.MethodsWES was proposed to 29 patients with severe undiagnosed disorders with developmental abnormalities and faced with medical situations requiring rapid diagnosis. Each family gave consent. The extracted DNA was sequenced on a NextSeq500 (Illumina) instrument. Data were analyzed following standard procedures. Variants were interpreted using in-house software. Each rare variant affecting protein sequences with clinical relevance was tested for familial segregation.ResultsThe diagnostic rate was 45% (13/29), with a mean turnaround time of 40 days from reception of the specimen to delivery of results to the referring physician. Besides permitting genetic counseling, the rapid diagnosis for positive families led to two pre-natal diagnoses and two inclusions in clinical trials.ConclusionsThis pilot study demonstrated the feasibility of rapid diagnostic WES in our primary genetics center. It reduced the diagnostic odyssey and helped provide support to families.     

Effectiveness of whole-exome sequencing and costs of the traditional diagnostic trajectory in children with intellectual disability

PurposeThis study investigated whole-exome sequencing (WES) yield in a subset of intellectually disabled patients referred to our clinical diagnostic center and calculated the total costs of these patients’ diagnostic trajectory in order to evaluate early WES implementation.MethodsWe compared 17 patients’ trio-WES yield with the retrospective costs of diagnostic procedures by comprehensively examining patient records and collecting resource use information for each patient, beginning with patient admittance and concluding with WES initiation. We calculated cost savings using scenario analyses to evaluate the costs replaced by WES when used as a first diagnostic tool.ResultsWES resulted in diagnostically useful outcomes in 29.4% of patients. The entire traditional diagnostic trajectory average cost was $16,409 per patient, substantially higher than the $3,972 trio-WES cost. WES resulted in average cost savings of $3,547 for genetic and metabolic investigations in diagnosed patients and $1,727 for genetic investigations in undiagnosed patients.ConclusionThe increased causal variant detection yield by WES and the relatively high costs of the entire traditional diagnostic trajectory suggest that early implementation of WES is a relevant and cost-efficient option in patient diagnostics. This information is crucial for centers considering implementation of WES and serves as input for future value-based research into diagnostics.Genet Med 18 9, 949–956.     

Using medical exome sequencing to identify the causes of neurodevelopmental disorders: Experience of 2 clinical units and 216 patients

Although whole‐exome sequencing (WES) is the gold standard for the diagnosis of neurodevelopmental disorders (NDDs), it remains expensive for some genetic centers. Commercialized panels comprising all OMIM‐referenced genes called “medical exome” (ME) constitute an alternative strategy to WES, but its efficiency is poorly known. In this study, we report the experience of 2 clinical genetic centers using ME for diagnosis of NDDs. We recruited 216 consecutive index patients with NDDs in 2 French genetic centers, corresponded to the daily practice of the units and included non‐syndromic intellectual disability (NSID, n = 33), syndromic ID (NSID = 122), pediatric neurodegenerative disorders (n = 7) and autism spectrum disorder (ASD, n = 54). We sequenced samples from probands and their parents (when available) with the Illumina TruSight One sequencing kit. We found pathogenic or likely pathogenic variants in 56 index patients, for a global diagnostic yield of 25.9%. The diagnosis yield was higher in patients with ID as the main diagnosis (32%) than in patients with ASD (3.7%). Our results suggest that the use of ME is a valuable strategy for patients with ID when WES cannot be used as a routine diagnosis tool.     

Clinical utility of next-generation sequencing for inherited bone marrow failure syndromes

PurposePrecise genetic diagnosis of inherited bone marrow failure syndromes (IBMFS), a heterogeneous group of genetic disorders, is challenging but essential for precise clinical decision making.MethodsWe analyzed 121 IBMFS patients using a targeted sequencing covering 184 associated genes and 250 IBMFS patients using whole-exome sequencing (WES).ResultsWe achieved successful genetic diagnoses for 53 of 121 patients (44%) using targeted sequencing and for 68 of 250 patients (27%) using WES. In the majority of cases (targeted sequencing: 45/53, 85%; WES: 63/68, 93%), the detected variants were concordant with, and therefore supported, the clinical diagnoses. However, in the remaining 13 cases (8 patients by target sequencing and 5 patients by WES), the clinical diagnoses were incompatible with the detected variants.ConclusionOur approach utilizing targeted sequencing and WES achieved satisfactory diagnostic rates and supported the efficacy of massive parallel sequencing as a diagnostic tool for IBMFS.Genet Med advance online publication 19 January 2017     

A prospective evaluation of whole-exome sequencing as a first-tier molecular test in infants with suspected monogenic disorders

PurposeTo prospectively evaluate the diagnostic and clinical utility of singleton whole-exome sequencing (WES) as a first-tier test in infants with suspected monogenic disease.MethodsSingleton WES was performed as a first-tier sequencing test in infants recruited from a single pediatric tertiary center. This occurred in parallel with standard investigations, including single- or multigene panel sequencing when clinically indicated. The diagnosis rate, clinical utility, and impact on management of singleton WES were evaluated.ResultsOf 80 enrolled infants, 46 received a molecular genetic diagnosis through singleton WES (57.5%) compared with 11 (13.75%) who underwent standard investigations in the same patient group. Clinical management changed following exome diagnosis in 15 of 46 diagnosed participants (32.6%). Twelve relatives received a genetic diagnosis following cascade testing, and 28 couples were identified as being at high risk of recurrence in future pregnancies.ConclusionsThis prospective study provides strong evidence for increased diagnostic and clinical utility of singleton WES as a first-tier sequencing test for infants with a suspected monogenic disorder. Singleton WES outperformed standard care in terms of diagnosis rate and the benefits of a diagnosis, namely, impact on management of the child and clarification of reproductive risks for the extended family in a timely manner.Genet Med 18 11, 1090–1096.     

Prospective comparison of the cost-effectiveness of clinical whole-exome sequencing with that of usual care overwhelmingly supports early use and reimbursement

PurposeTo undertake the first prospective cost-effectiveness study of whole-exome sequencing (WES) as an early, routine clinical test for infants with suspected monogenic disorders.MethodsCost data for diagnosis-related investigations and assessments were collected for a prospective, sequential clinical cohort of infants (N = 40) who underwent singleton WES in parallel to usual diagnostic care. We determined costs per patient, costs per diagnosis, and incremental costs per additional diagnosis for three alternative strategies for integrating WES into the diagnostic trajectory. We performed a sensitivity analysis to examine the robustness of estimates and bootstrapping (500 replications) to examine their distributions.ResultsStandard care achieved an average cost per diagnosis of AU$27,050 (US$21,099) compared with AU$5,047 (US$3,937) for singleton WES. If WES had been performed after exhaustive standard investigation, then there would have been an incremental cost per additional diagnosis of AU$8,112 (US$ 6,327). Using WES to replace some investigations decreases this incremental cost to AU$2,622 (US$2,045), whereas using it to replace most investigations results in a savings per additional diagnosis of AU$2,182 (US$1,702).ConclusionUse of WES early in the diagnostic pathway more than triples the diagnostic rate for one-third the cost per diagnosis, providing strong support for reimbursement as a clinical test.Genet Med advance online publication 26 January 2017     

A clinical utility study of exome sequencing versus conventional genetic testing in pediatric neurology

PurposeImplementation of novel genetic diagnostic tests is generally driven by technological advances because they promise shorter turnaround times and/or higher diagnostic yields. Other aspects, including impact on clinical management or cost-effectiveness, are often not assessed in detail prior to implementation.MethodsWe studied the clinical utility of whole-exome sequencing (WES) in complex pediatric neurology in terms of diagnostic yield and costs. We analyzed 150 patients (and their parents) presenting with complex neurological disorders of suspected genetic origin. In a parallel study, all patients received both the standard diagnostic workup (e.g., cerebral imaging, muscle biopsies or lumbar punctures, and sequential gene-by-gene–based testing) and WES simultaneously.ResultsOur unique study design allowed direct comparison of diagnostic yield of both trajectories and provided insight into the economic implications of implementing WES in this diagnostic trajectory. We showed that WES identified significantly more conclusive diagnoses (29.3%) than the standard care pathway (7.3%) without incurring higher costs. Exploratory analysis of WES as a first-tier diagnostic test indicates that WES may even be cost-saving, depending on the extent of other tests being omitted.ConclusionOur data support such a use of WES in pediatric neurology for disorders of presumed genetic origin.Genet Med advance online publication 23 March 2017     

Does genomic sequencing early in the diagnostic trajectory make a difference? A follow-up study of clinical outcomes and cost-effectiveness

PurposeTo systematically investigate the longer-term clinical and health economic impacts of genomic sequencing for rare-disease diagnoses.MethodsWe collected information on continuing diagnostic investigation, changes in management, cascade testing, and parental reproductive outcomes in 80 infants who underwent singleton whole-exome sequencing (WES).ResultsThe median duration of follow-up following result disclosure was 473 days. Changes in clinical management due to diagnostic WES results led to a cost saving of AU$1,578 per quality-adjusted life year gained, without increased hospital service use. Uninformative WES results contributed to the diagnosis of non-Mendelian conditions in seven infants. Further usual diagnostic investigations in those with ongoing suspicion of a genetic condition yielded no new diagnoses, while WES data reanalysis yielded four. Reanalysis at 18 months was more cost-effective than every 6 months. The parents of diagnosed children had eight more ongoing pregnancies than those without a diagnosis. Taking the costs and benefits of cascade testing and reproductive service use into account, there was an additional cost of AU$8,118 per quality-adjusted life year gained due to genomic sequencing.ConclusionThese data strengthen the case for the early use of genomic testing in the diagnostic trajectory, and can guide laboratory policy on periodic WES data reanalysis.     

Clinical application of whole-exome sequencing across clinical indications

PurposeWe report the diagnostic yield of whole-exome sequencing (WES) in 3,040 consecutive cases at a single clinical laboratory.MethodsWES was performed for many different clinical indications and included the proband plus two or more family members in 76% of cases.ResultsThe overall diagnostic yield of WES was 28.8%. The diagnostic yield was 23.6% in proband-only cases and 31.0% when three family members were analyzed. The highest yield was for patients who had disorders involving hearing (55%, N = 11), vision (47%, N = 60), the skeletal muscle system (40%, N = 43), the skeletal system (39%, N = 54), multiple congenital anomalies (36%, N = 729), skin (32%, N = 31), the central nervous system (31%, N = 1,082), and the cardiovascular system (28%, N = 54). Of 2,091 cases in which secondary findings were analyzed for 56 American College of Medical Genetics and Genomics–recommended genes, 6.2% (N = 129) had reportable pathogenic variants. In addition to cases with a definitive diagnosis, in 24.2% of cases a candidate gene was reported that may later be reclassified as being associated with a definitive diagnosis.ConclusionOur experience with our first 3,040 WES cases suggests that analysis of trios significantly improves the diagnostic yield compared with proband-only testing for genetically heterogeneous disorders and facilitates identification of novel candidate genes.     

Clinical validity of phenotype-driven analysis software PhenoVar as a diagnostic aid for clinical geneticists in the interpretation of whole-exome sequencing data

PurposeWe sought to determine the diagnostic yield of whole-exome sequencing (WES) combined with phenotype-driven analysis of variants in patients with suspected genetic disorders.MethodsWES was performed on a cohort of 51 patients presenting dysmorphisms with or without neurodevelopmental disorders of undetermined etiology. For each patient, a clinical geneticist reviewed the phenotypes and used the phenotype-driven analysis software PhenoVar (http://phenovar.med.usherbrooke.ca/) to analyze WES variants. The prioritized list of potential diagnoses returned was reviewed by the clinical geneticist, who selected candidate variants to be confirmed by segregation analysis. Conventional analysis of the individual variants was performed in parallel. The resulting candidate variants were subsequently reviewed by the same geneticist, to identify any additional potential diagnoses.ResultsA molecular diagnosis was identified in 35% of the patients using the conventional analysis, and 17 of these 18 diagnoses were independently identified using PhenoVar. The only diagnosis initially missed by PhenoVar was rescued when the optional “minimal phenotypic cutoff” filter was omitted. PhenoVar reduced by half the number of potential diagnoses per patient compared with the conventional analysis.ConclusionPhenotype-driven software prioritizes WES variants, provides an efficient diagnostic aid to clinical geneticists and laboratories, and should be incorporated in clinical practice.     

Practical considerations in the clinical application of whole‐exome sequencing

Despite the exciting advent of whole‐exome sequencing (WES) in medical genetics practices, the optimal interpretation of results requires further actions such as reconsidering clinical information and obtaining further laboratory testing. There are no published data to guide clinicians in this process. In a retrospective study on 93 patients who underwent clinical WES, we set out to assess and resolve these practical challenges. With the laboratories reporting a molecular diagnostic rate of 25.8%, the medical geneticists and the laboratories were 90% concordant in their interpretation of the WES results. Divergence occurred when the medical geneticist reconsidered clinical information and/or additional information regarding pathogenicity of a variant. Variants of uncertain significance were reported in 86% of patients, with 53.7% needing follow‐up, such as additional laboratory tests and genotyping of family members. By layering clinical data (e.g. mode of inheritance and phenotypic fit) on to the laboratory results, we developed clinical categories for the WES results. These categories of definite diagnosis (14/93), likely diagnosis (8/93), possible diagnosis (13/93) and no diagnosis (58/93) could be used to convey results to patients uniformly. Our framework for a clinically informed interpretation of the results enhances the utility of WES within medical genetics practices.     

Systematic reanalysis of clinical exome data yields additional diagnoses: implications for providers

PurposeClinical exome sequencing is nondiagnostic for about 75% of patients evaluated for a possible Mendelian disorder. We examined the ability of systematic reevaluation of exome data to establish additional diagnoses.MethodsThe exome and phenotypic data of 40 individuals with previously nondiagnostic clinical exomes were reanalyzed with current software and literature.ResultsA definitive diagnosis was identified for 4 of 40 participants (10%). In these cases the causative variant is de novo and in a relevant autosomal-dominant disease gene. The literature to tie the causative genes to the participants’ phenotypes was weak, nonexistent, or not readily located at the time of the initial clinical exome reports. At the time of diagnosis by reanalysis, the supporting literature was 1 to 3 years old.ConclusionApproximately 250 gene–disease and 9,200 variant–disease associations are reported annually. This increase in information necessitates regular reevaluation of nondiagnostic exomes. To be practical, systematic reanalysis requires further automation and more up-to-date variant databases. To maximize the diagnostic yield of exome sequencing, providers should periodically request reanalysis of nondiagnostic exomes. Accordingly, policies regarding reanalysis should be weighed in combination with factors such as cost and turnaround time when selecting a clinical exome laboratory.     

Genomic diagnostics within a medically underserved population: efficacy and implications

PurposeWe integrated whole-exome sequencing (WES) and chromosomal microarray analysis (CMA) into a clinical workflow to serve an endogamous, uninsured, agrarian community.MethodsSeventy-nine probands (newborn to 49.8 years) who presented between 1998 and 2015 remained undiagnosed after biochemical and molecular investigations. We generated WES data for probands and family members and vetted variants through rephenotyping, segregation analyses, and population studies.ResultsThe most common presentation was neurological disease (64%). Seven (9%) probands were diagnosed by CMA. Family WES data were informative for 37 (51%) of the 72 remaining individuals, yielding a specific genetic diagnosis (n = 32) or revealing a novel molecular etiology (n = 5). For five (7%) additional subjects, negative WES decreased the likelihood of genetic disease. Compared to trio analysis, “family” WES (average seven exomes per proband) reduced filtered candidate variants from 22 ± 6 to 5 ± 3 per proband. Nineteen (51%) alleles were de novo and 17 (46%) inherited; the latter added to a population-based diagnostic panel. We found actionable secondary variants in 21 (4.2%) of 502 subjects, all of whom opted to be informed.ConclusionCMA and family-based WES streamline and economize diagnosis of rare genetic disorders, accelerate novel gene discovery, and create new opportunities for community-based screening and prevention in underserved populations.     

Molecular diagnostic experience of whole-exome sequencing in adult patients

PurposeWhole-exome sequencing (WES) is increasingly used as a diagnostic tool in medicine, but prior reports focus on predominantly pediatric cohorts with neurologic or developmental disorders. We describe the diagnostic yield and characteristics of WES in adults.MethodsWe performed a retrospective analysis of consecutive WES reports for adults from a diagnostic laboratory. Phenotype composition was determined using Human Phenotype Ontology terms.ResultsMolecular diagnoses were reported for 17.5% (85/486) of adults, which is lower than that for a primarily pediatric population (25.2%; P = 0.0003); the diagnostic rate was higher (23.9%) for those 18–30 years of age compared to patients older than 30 years (10.4%; P = 0.0001). Dual Mendelian diagnoses contributed to 7% of diagnoses, revealing blended phenotypes. Diagnoses were more frequent among individuals with abnormalities of the nervous system, skeletal system, head/neck, and growth. Diagnostic rate was independent of family history information, and de novo mutations contributed to 61.4% of autosomal dominant diagnoses.ConclusionEarly WES experience in adults demonstrates molecular diagnoses in a substantial proportion of patients, informing clinical management, recurrence risk, and recommendations for relatives. A positive family history was not predictive, consistent with molecular diagnoses often revealed by de novo events, informing the Mendelian basis of genetic disease in adults.     

Solve-RD: systematic pan-European data sharing and collaborative analysis to solve rare diseases

For the first time in Europe hundreds of rare disease (RD) experts team up to actively share and jointly analyse existing patient’s data. Solve-RD is a Horizon 2020-supported EU flagship project bringing together >300 clinicians, scientists, and patient representatives of 51 sites from 15 countries. Solve-RD is built upon a core group of four European Reference Networks (ERNs; ERN-ITHACA, ERN-RND, ERN-Euro NMD, ERN-GENTURIS) which annually see more than 270,000 RD patients with respective pathologies. The main ambition is to solve unsolved rare diseases for which a molecular cause is not yet known. This is achieved through an innovative clinical research environment that introduces novel ways to organise expertise and data. Two major approaches are being pursued (i) massive data re-analysis of >19,000 unsolved rare disease patients and (ii) novel combined -omics approaches. The minimum requirement to be eligible for the analysis activities is an inconclusive exome that can be shared with controlled access. The first preliminary data re-analysis has already diagnosed 255 cases form 8393 exomes/genome datasets. This unprecedented degree of collaboration focused on sharing of data and expertise shall identify many new disease genes and enable diagnosis of many so far undiagnosed patients from all over Europe.Subject terms: Medical genetics, Diseases

Rare Diseases (RD) are individually rare but collectively a common health issue. Around 80% of RD are estimated to have a genetic cause [1]. The time to a genetic diagnosis however often takes several years and initial clinical diagnoses are incorrect in up to 40% of families [2]. Around 50% of patients with a RD remain undiagnosed even in advanced expert clinical settings where whole exome sequencing (WES) is applied routinely as a diagnostic approach. Depending on the exact diagnostic setting, the inclusion criteria and the type of RD, the diagnostic yield from WES ranges between 15 and 51% of cases [3, 4].At least two scenarios allow boosting the current yield of WES. Firstly, there is a value in re-analysing WES data regularly [5] and on massive scale [6], but not every RD expert has access to tools enabling this systematically. Secondly, it is clear that moving beyond the exome can provide additional benefits [7, 8].Solve-RD aims to solve a large number of unsolved RD, for which a molecular cause is not yet known, by implementing both strategies mentioned above. To this end, Solve-RD applies innovative ways to effectively organise expertise and data.     

Genetic Testing in Egyptian Patients with Inborn Errors of Immunity: a Single-Center Experience

Background

Inborn errors of immunity (IEI) are a group of heterogeneous disorders with geographic and ethnic diversities. Although IEI are common in Egypt, genetic diagnosis is limited due to financial restrictions. This study aims to characterize the genetic spectrum of IEI patients in Egypt and highlights the adaptation of the molecular diagnostic methods to a resource-limited setting.

Methods

Genetic material from 504 patients was studied, and proper diagnosis was achieved in 282 patients from 246 families. Mutational analysis was done by Sanger sequencing, next-generation sequencing (NGS) targeting customized genes panels, and whole-exome sequencing (WES) according to the patients’ phenotypes and availability of genetic testing.

Results

A total of 194 variants involving 72 different genes were detected with RAG1/2 genes being the most encountered followed by DOCK8, CYBA, LRBA, NCF1, and JAK3. Autosomal recessive (AR) inheritance was detected in 233/282 patients (82.6%), X-linked (XL) recessive inheritance in 32/282 patients (11.3%), and autosomal dominant (AD) inheritance in 18/282 patients (6.4%), reflecting the impact of consanguineous marriages on the prevalence of different modes of inheritance and the distribution of the various IEI disorders.

Conclusion

The study showed that a combination of Sanger sequencing in selected patients associated with targeted NGS or WES in other patients is an effective diagnostic strategy for IEI diagnosis in countries with limited diagnostic resources. Molecular testing can be used to validate other nonexpensive laboratory techniques that help to reach definitive diagnosis and help in genetic counseling and taking proper therapeutic decisions including stem cell transplantation or gene therapy.

     

Making new genetic diagnoses with old data: iterative reanalysis and reporting from genome-wide data in 1,133 families with developmental disorders

PurposeGiven the rapid pace of discovery in rare disease genomics, it is likely that improvements in diagnostic yield can be made by systematically reanalyzing previously generated genomic sequence data in light of new knowledge.MethodsWe tested this hypothesis in the United Kingdom–wide Deciphering Developmental Disorders study, where in 2014 we reported a diagnostic yield of 27% through whole-exome sequencing of 1,133 children with severe developmental disorders and their parents. We reanalyzed existing data using improved variant calling methodologies, novel variant detection algorithms, updated variant annotation, evidence-based filtering strategies, and newly discovered disease-associated genes.ResultsWe are now able to diagnose an additional 182 individuals, taking our overall diagnostic yield to 454/1,133 (40%), and another 43 (4%) have a finding of uncertain clinical significance. The majority of these new diagnoses are due to novel developmental disorder–associated genes discovered since our original publication.ConclusionThis study highlights the importance of coupling large-scale research with clinical practice, and of discussing the possibility of iterative reanalysis and recontact with patients and health professionals at an early stage. We estimate that implementing parent–offspring whole-exome sequencing as a first-line diagnostic test for developmental disorders would diagnose >50% of patients.     

The utility of the traditional medical genetics diagnostic evaluation in the context of next-generation sequencing for undiagnosed genetic disorders

PurposeThe purpose of this study was to assess the diagnostic yield of the traditional, comprehensive clinical evaluation and targeted genetic testing, within a general genetics clinic. These data are critically needed to develop clinically and economically grounded diagnostic algorithms that consider presenting phenotype, traditional genetics testing, and the emerging role of next-generation sequencing (whole-exome/genome sequencing).MethodsWe retrospectively analyzed a cohort of 500 unselected consecutive patients who received traditional genetic diagnostic evaluations at a tertiary medical center. We calculated the diagnosis rate, number of visits to diagnosis, genetic tests, and the cost of testing.ResultsThirty-nine patients were determined to not have a genetic disorder; 212 of the remaining 461 (46%) received a genetic diagnosis, and 72% of these were diagnosed on the first visit. The cost per subsequent successful genetic diagnosis was estimated at $25,000.ConclusionAlmost half of the patients were diagnosed using the traditional approach, most at the initial visit. For those remaining undiagnosed, next-generation sequencing may be clinically and economically beneficial. Estimating a 50% success rate for next-generation sequencing in undiagnosed genetic disorders, its application after the first clinical visit could result in a higher rate of genetic diagnosis at a considerable cost savings per successful diagnosis.Genet Med16 2, 176–182.