Glucose transporter-1 deficiency syndrome: the expanding clinical and genetic spectrum of a treatable disorder

Glucose transporter-1 deficiency syndrome is caused by mutations in the SLC2A1 gene in the majority of patients and results in impaired glucose transport into the brain. From 2004-2008, 132 requests for mutational analysis of the SLC2A1 gene were studied by automated Sanger sequencing and multiplex ligation-dependent probe amplification. Mutations in the SLC2A1 gene were detected in 54 patients (41%) and subsequently in three clinically affected family members. In these 57 patients we identified 49 different mutations, including six multiple exon deletions, six known mutations and 37 novel mutations (13 missense, five nonsense, 13 frame shift, four splice site and two translation initiation mutations). Clinical data were retrospectively collected from referring physicians by means of a questionnaire. Three different phenotypes were recognized: (i) the classical phenotype (84%), subdivided into early-onset (<2 years) (65%) and late-onset (18%); (ii) a non-classical phenotype, with mental retardation and movement disorder, without epilepsy (15%); and (iii) one adult case of glucose transporter-1 deficiency syndrome with minimal symptoms. Recognizing glucose transporter-1 deficiency syndrome is important, since a ketogenic diet was effective in most of the patients with epilepsy (86%) and also reduced movement disorders in 48% of the patients with a classical phenotype and 71% of the patients with a non-classical phenotype. The average delay in diagnosing classical glucose transporter-1 deficiency syndrome was 6.6 years (range 1 month-16 years). Cerebrospinal fluid glucose was below 2.5 mmol/l (range 0.9-2.4 mmol/l) in all patients and cerebrospinal fluid : blood glucose ratio was below 0.50 in all but one patient (range 0.19-0.52). Cerebrospinal fluid lactate was low to normal in all patients. Our relatively large series of 57 patients with glucose transporter-1 deficiency syndrome allowed us to identify correlations between genotype, phenotype and biochemical data. Type of mutation was related to the severity of mental retardation and the presence of complex movement disorders. Cerebrospinal fluid : blood glucose ratio was related to type of mutation and phenotype. In conclusion, a substantial number of the patients with glucose transporter-1 deficiency syndrome do not have epilepsy. Our study demonstrates that a lumbar puncture provides the diagnostic clue to glucose transporter-1 deficiency syndrome and can thereby dramatically reduce diagnostic delay to allow early start of the ketogenic die

Future of Dutch NGS-Based Newborn Screening: Exploring the Technical Possibilities and Assessment of a Variant Classification Strategy

In this study, we compare next-generation sequencing (NGS) approaches (targeted panel (tNGS), whole exome sequencing (WES), and whole genome sequencing (WGS)) for application in newborn screening (NBS). DNA was extracted from dried blood spots (DBS) from 50 patients with genetically confirmed inherited metabolic disorders (IMDs) and 50 control samples. One hundred IMD-related genes were analyzed. Two data-filtering strategies were applied: one to detect only (likely) pathogenic ((L)P) variants, and one to detect (L)P variants in combination with variants of unknown significance (VUS). The variants were filtered and interpreted, defining true/false positives (TP/FP) and true/false negatives (TN/FN). The variant filtering strategies were assessed in a background cohort (BC) of 4833 individuals. Reliable results were obtained within 5 days. TP results (47 patient samples) for tNGS, WES, and WGS results were 33, 31, and 30, respectively, using the (L)P filtering, and 40, 40, and 38, respectively, when including VUS. FN results were 11, 13, and 14, respectively, excluding VUS, and 4, 4, and 6, when including VUS. The remaining FN were mainly samples with a homozygous VUS. All controls were TN. Three BC individuals showed a homozygous (L)P variant, all related to a variable, mild phenotype. The use of NGS-based workflows in NBS seems promising, although more knowledge of data handling, automated variant interpretation, and costs is needed before implementation

Twist exome capture allows for lower average sequence coverage in clinical exome sequencing

Background Exome and genome sequencing are the predominant techniques in the diagnosis and research of genetic disorders. Sufficient, uniform and reproducible/consistent sequence coverage is a main determinant for the sensitivity to detect single-nucleotide (SNVs) and copy number variants (CNVs). Here we compared the ability to obtain comprehensive exome coverage for recent exome capture kits and genome sequencing techniques. Results We compared three different widely used enrichment kits (Agilent SureSelect Human All Exon V5, Agilent SureSelect Human All Exon V7 and Twist Bioscience) as well as short-read and long-read WGS. We show that the Twist exome capture significantly improves complete coverage and coverage uniformity across coding regions compared to other exome capture kits. Twist performance is comparable to that of both short- and long-read whole genome sequencing. Additionally, we show that even at a reduced average coverage of 70× there is only minimal loss in sensitivity for SNV and CNV detection. Conclusion We conclude that exome sequencing with Twist represents a significant improvement and could be performed at lower sequence coverage compared to other exome capture techniques

Winkel van de toekomst, toekomst van de winkel?

Dit boekje geeft de resultaten weer van het project Future Store van het Saxion Kenniscentrum Design en Technologie. Het gedrag, de behoeften van de consument, trends en de technologische ontwikkelingen veranderen in een rap tempo. Om deze veranderingen te kunnen bijbenen hebben retailers, MKB- bedrijven en kennisinstellingen samen ervaring opgedaan en kennis gedeeld in het project Future Store. Studenten hebben onder andere vragen beantwoord over de invloed van sociale media op het consumentengedrag. Er is gekeken naar de werking en verandering van het winkelproces in een nieuwe technologische winkelomgeving, online en fysiek. En leiden alle &lsquo;snufjes&rsquo; tot meer omzet en tevreden klanten? Ook zijn er vraagstellingen beantwoord op het gebied van visualisatie. Wanneer je het winkelproces wilt aanpassen met nieuwe technische snufjes of wilt inspelen op trends of het veranderende gedrag van de consument, dan moet je het winkelproces eerst leren begrijpen. Wij hebben het winkelproces in zes stappen in kaart gebracht. De eerste drie stappen spelen zich af in de pre-store fase: consumentisme, be&iuml;nvloeding die een koopintentie veroorzaakt en de koopplanning. Stap 4 en 5 vinden binnen de winkel plaats (in-store), namelijk de kanaal- en winkelkeuze, wat uiteindelijk leidt tot afweging en koop. Uiteindelijk wordt de koop ge&euml;valueerd, wat weer kan leiden tot een nieuwe koopintentie. Al deze stappen zijn niet vanzelfsprekend. Er zijn situaties waarin een consument een ander proces volgt. De mening van de consument verandert voortdurend door allerlei factoren. Wanneer de consument zich in de winkel bevindt en zich ori&euml;nteert, kan hij/zij behoefte hebben of waarde hechten aan meningen en adviezen van vrienden. Ook vertrouwenscriteria, zoals de reputatie van een merk/winkel, de ervaringen met een after sales service en zelfkennis kunnen het winkelproces be&iuml;nvloeden en een bepaald gevoel bij een product cre&euml;ren. Vooral ICT kan het winkelproces be&iuml;nvloeden. Denk aan de bodyscanner die secuur je maten opmeet, waardoor je uiteindelijk meer draagplezier hebt van je kleding. Ook kunnen consumenten via mobiele telefoons en sociale media binnen de winkel met de buitenwereld communiceren. Hierdoor gaan de klassieke &lsquo;pre-store&rsquo; en &lsquo;in-store&rsquo; door elkaar lopen. Om discussie te cre&euml;ren hebben we vier toekomstscenario&rsquo;s beschreven: 1. We gaan passen zonder passen. Op een scherm zie je een virtueel 3D-model van jou als persoon en kun je de kleding kiezen uit het zichtbare virtuele assortiment. Zo kun je direct je nieuwe outfit cre&euml;ren en via internet delen met vrienden. 2. De &lsquo;ambient store&rsquo; past zich aan aan jouw behoeften en vult zich met je favoriete muziek. Het ritme van de muziek is afgestemd op een bepaalde geur die je prikkelt en je onbewust de behoefte geeft om langer in de winkel te blijven. 3. De &lsquo;Social Shopper&rsquo; gebruikt sociale media tijdens het online winkelen of, in de fysieke winkel, op zijn smartphone. Meningen worden uitgewisseld op sociale media netwerken en reviewsites. Merken en winkels volgen de berichten over hun producten en proberen de discussies te be&iuml;nvloeden en van hun klanten te leren. 4. In de winkel van de toekomst draait het om beleving. Je gaat naar een winkel met een virtuele catwalk show, waarop virtuele modellen lopen in kleding die is geselecteerd op jouw behoeften. Elk kledingstuk is in 3D afgebeeld op een glazen scherm met bijbehorende productinformatie. Na afloop kun je kleding en accessoires passen en kopen. De toekomst van de winkel? Het winkelgedrag in Nederland is de afgelopen jaren sterk veranderd. Dit heeft te maken met online winkelen, de crisis, beperkte openingstijden, parkeerproblemen, verpauperde winkelstraten door leegstand en het gebrek aan verassing door de grote hoeveelheid landelijke ketens. Maar er is hoop voor de winkels en daarmee voor de winkelgebie

Wear behaviour of discontinuous aramid fibre reinforced ultra-high molecular weight polyethylene

The wear of Ultra-High Molecular Weight Polyethylene has generated new concern regarding the long-term clinical performance of total joint replacements. To extend the lifetime of artificial joints, it is necessary to decrease tt-le wear rate of UHMWPE. One possible solution is the incorporation of aramid fibres. Wear rates were determined with a pin-on-roll apparatus with a nominal contact stress of 3.0 MPa at a sliding velocity of 0.24 m/s. The volumetric wear rate decreases with the incorporation of the fibres. A minimum in wear rate is observed at 5 volume percent fibres

Reliability and validity of the Microgate Gyko for measuring range of motion of the low back

Background: The aim of this study was to test the inter- and intrarater reliability and the concurrent validity of the Gyko Microgate for the assessment of lumbar range of motion. Methods: A cross-sectional study was carried out with two groups of healthy participants. The first group, consisting of 91 subjects, was tested to determine the inter- and intrarater reliability. Concurrent validity was assessed with comparisons with an optical motion system (Vicon) in a second group of 20 subjects. Lumbar range of motion in flexion, extension, left and right lateral flexion were performed. Intraclass correlation coefficient (ICC) was calculated for both analyses. Measurement error was calculated with standard error of the measurement (SEM), smallest detectable change (SDC) and Limits of Agreement (LoA). ICCs were considered good when ICC ≥0.80 and excellent with ICC ≥0.90. Results: Interrater reliability was good to excellent with ICCs ranging from 0.82 to 0.94. Intrarater reliability was good to excellent with ICCs ranging from 0.84 to 0.95. Concurrent validity was excellent with ICCs varying from 0.90 to 0.95. LoA were highest in interrater reliability and smallest in concurrent validity. SEM ranged from 2.2 to 4.0° in lateral flexion left and flexion respectively. SDC varied from 6.1 to 11.1°. Conclusion: Gyko has good inter- and intrarater reliability and excellent concurrent validity compared to the optical motion system for lumbar range of motion. Gyko may be considered as objective measure to measure range of motion for clinical purposes, however trials with patients are currently lacking

Future of Dutch NGS-Based Newborn Screening:Exploring the Technical Possibilities and Assessment of a Variant Classification Strategy

In this study, we compare next-generation sequencing (NGS) approaches (targeted panel (tNGS), whole exome sequencing (WES), and whole genome sequencing (WGS)) for application in newborn screening (NBS). DNA was extracted from dried blood spots (DBS) from 50 patients with genetically confirmed inherited metabolic disorders (IMDs) and 50 control samples. One hundred IMD-related genes were analyzed. Two data-filtering strategies were applied: one to detect only (likely) pathogenic ((L)P) variants, and one to detect (L)P variants in combination with variants of unknown significance (VUS). The variants were filtered and interpreted, defining true/false positives (TP/FP) and true/false negatives (TN/FN). The variant filtering strategies were assessed in a background cohort (BC) of 4833 individuals. Reliable results were obtained within 5 days. TP results (47 patient samples) for tNGS, WES, and WGS results were 33, 31, and 30, respectively, using the (L)P filtering, and 40, 40, and 38, respectively, when including VUS. FN results were 11, 13, and 14, respectively, excluding VUS, and 4, 4, and 6, when including VUS. The remaining FN were mainly samples with a homozygous VUS. All controls were TN. Three BC individuals showed a homozygous (L)P variant, all related to a variable, mild phenotype. The use of NGS-based workflows in NBS seems promising, although more knowledge of data handling, automated variant interpretation, and costs is needed before implementation.</p

Reanalysis of exome negative patients with rare disease: a pragmatic workflow for diagnostic applications

Background Approximately two third of patients with a rare genetic disease remain undiagnosed after exome sequencing (ES). As part of our post-test counseling procedures, patients without a conclusive diagnosis are advised to recontact their referring clinician to discuss new diagnostic opportunities in due time. We performed a systematic study of genetically undiagnosed patients 5 years after their initial negative ES report to determine the efficiency of diverse reanalysis strategies. Methods We revisited a cohort of 150 pediatric neurology patients originally enrolled at Radboud University Medical Center, of whom 103 initially remained genetically undiagnosed. We monitored uptake of physician-initiated routine clinical and/or genetic re-evaluation (ad hoc re-evaluation) and performed systematic reanalysis, including ES-based resequencing, of all genetically undiagnosed patients (systematic re-evaluation). Results Ad hoc re-evaluation was initiated for 45 of 103 patients and yielded 18 diagnoses (including 1 non-genetic). Subsequent systematic re-evaluation identified another 14 diagnoses, increasing the diagnostic yield in our cohort from 31% (47/150) to 53% (79/150). New genetic diagnoses were established by reclassification of previously identified variants (10%, 3/31), reanalysis with enhanced bioinformatic pipelines (19%, 6/31), improved coverage after resequencing (29%, 9/31), and new disease-gene associations (42%, 13/31). Crucially, our systematic study also showed that 11 of the 14 further conclusive genetic diagnoses were made in patients without a genetic diagnosis that did not recontact their referring clinician. Conclusions We find that upon re-evaluation of undiagnosed patients, both reanalysis of existing ES data as well as resequencing strategies are needed to identify additional genetic diagnoses. Importantly, not all patients are routinely re-evaluated in clinical care, prolonging their diagnostic trajectory, unless systematic reanalysis is facilitated. We have translated our observations into considerations for systematic and ad hoc reanalysis in routine genetic care