SUPPORT Tools for evidence-informed health Policymaking (STP) 7: Finding systematic reviews

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Identification of genetic variants associated with Huntington's disease progression: a genome-wide association study

Background Huntington's disease is caused by a CAG repeat expansion in the huntingtin gene, HTT. Age at onset has been used as a quantitative phenotype in genetic analysis looking for Huntington's disease modifiers, but is hard to define and not always available. Therefore, we aimed to generate a novel measure of disease progression and to identify genetic markers associated with this progression measure. Methods We generated a progression score on the basis of principal component analysis of prospectively acquired longitudinal changes in motor, cognitive, and imaging measures in the 218 indivduals in the TRACK-HD cohort of Huntington's disease gene mutation carriers (data collected 2008–11). We generated a parallel progression score using data from 1773 previously genotyped participants from the European Huntington's Disease Network REGISTRY study of Huntington's disease mutation carriers (data collected 2003–13). We did a genome-wide association analyses in terms of progression for 216 TRACK-HD participants and 1773 REGISTRY participants, then a meta-analysis of these results was undertaken. Findings Longitudinal motor, cognitive, and imaging scores were correlated with each other in TRACK-HD participants, justifying use of a single, cross-domain measure of disease progression in both studies. The TRACK-HD and REGISTRY progression measures were correlated with each other (r=0·674), and with age at onset (TRACK-HD, r=0·315; REGISTRY, r=0·234). The meta-analysis of progression in TRACK-HD and REGISTRY gave a genome-wide significant signal (p=1·12 × 10−10) on chromosome 5 spanning three genes: MSH3, DHFR, and MTRNR2L2. The genes in this locus were associated with progression in TRACK-HD (MSH3 p=2·94 × 10−8 DHFR p=8·37 × 10−7 MTRNR2L2 p=2·15 × 10−9) and to a lesser extent in REGISTRY (MSH3 p=9·36 × 10−4 DHFR p=8·45 × 10−4 MTRNR2L2 p=1·20 × 10−3). The lead single nucleotide polymorphism (SNP) in TRACK-HD (rs557874766) was genome-wide significant in the meta-analysis (p=1·58 × 10−8), and encodes an aminoacid change (Pro67Ala) in MSH3. In TRACK-HD, each copy of the minor allele at this SNP was associated with a 0·4 units per year (95% CI 0·16–0·66) reduction in the rate of change of the Unified Huntington's Disease Rating Scale (UHDRS) Total Motor Score, and a reduction of 0·12 units per year (95% CI 0·06–0·18) in the rate of change of UHDRS Total Functional Capacity score. These associations remained significant after adjusting for age of onset. Interpretation The multidomain progression measure in TRACK-HD was associated with a functional variant that was genome-wide significant in our meta-analysis. The association in only 216 participants implies that the progression measure is a sensitive reflection of disease burden, that the effect size at this locus is large, or both. Knockout of Msh3 reduces somatic expansion in Huntington's disease mouse models, suggesting this mechanism as an area for future therapeutic investigation

Melanoma staging: Varying precision and terminal digit clustering in Breslow thickness data is evident in a population-based study

Background Errors in Breslow thickness reporting can give misclassification of T category, an important classifier in melanoma staging. Objective We sought to investigate precision (number of digits) and terminal digit clustering in Breslow thickness and potential consequences for T category. Methods All first primary and morphologically verified invasive melanomas in Norway between 2008 and 2015 were included. A smoothing model was fitted to estimate the underlying Breslow thickness distribution without digit clustering. Results Thickness was reported for 13,057 (97.5%) patients; the median was 1.0 mm (range, 0.09-85). It was reported as whole numbers (15.6%), to 1 decimal (78.2%) and 2 decimal places (6.2%)—thin tumors with more precision than thick tumors. Terminal digit clustering was found with marked peaks in the observed frequency distribution for terminal digits 0 and 5, and with drops around these peaks. Terminal digit clustering increased proportions of patients classified with T1 and T4 tumors and decreased proportions classified with T2 and T3. Limitations Breslow thickness was not reported in 2.5% of cases. Conclusions The Norwegian recommendation of measurement to the nearest 0.1 mm was not followed. Terminal digit clustering was marked, with consequences for T category. Pathologists, clinicians, and epidemiologists should know that clustering of thickness data around T category cut points can impact melanoma staging with consequent effect on patient management and prognosis

Sample preparation approach influences pam50 risk of recurrence score in early breast cancer

The PAM50 gene expression subtypes and the associated risk of recurrence (ROR) score are used to predict the risk of recurrence and the benefits of adjuvant therapy in early-stage breast cancer. The Prosigna assay includes the PAM50 subtypes along with their clinicopathological features, and is approved for treatment recommendations for adjuvant hormonal therapy and chemotherapy in hormone-receptor-positive early breast cancer. The Prosigna test utilizes RNA extracted from macrodissected tumor cells obtained from formalin-fixed, paraffin-embedded (FFPE) tissue sections. However, RNA extracted from fresh-frozen (FF) bulk tissue without macrodissection is widely used for research purposes, and yields high-quality RNA for downstream analyses. To investigate the impact of the sample preparation approach on ROR scores, we analyzed 94 breast carcinomas included in an observational study that had available gene expression data from macrodissected FFPE tissue and FF bulk tumor tissue, along with the clinically approved Prosigna scores for the node-negative, hormone-receptor-positive, HER2-negative cases (n = 54). ROR scores were calculated in R; the resulting two sets of scores from FFPE and FF samples were compared, and treatment recommendations were evaluated. Overall, ROR scores calculated based on the macrodissected FFPE tissue were consistent with the Prosigna scores. However, analyses from bulk tissue yielded a higher proportion of cases classified as normal-like; these were samples with relatively low tumor cellularity, leading to lower ROR scores. When comparing ROR scores (low, intermediate, and high), discordant cases between the two preparation approaches were revealed among the luminal tumors; the recommended treatment would have changed in a minority of cases

Prognostic value of PAM50 and risk of recurrence score in patients with early-stage breast cancer with long-term follow-up

Background The aim of this study was to investigate the prognostic value of the PAM50 intrinsic subtypes and risk of recurrence (ROR) score in patients with early breast cancer and long-term follow-up. A special focus was placed on hormone receptor-positive/human epidermal growth factor receptor 2-negative (HR+/HER2−) pN0 patients not treated with chemotherapy. Methods Patients with early breast cancer (n = 653) enrolled in the observational Oslo1 study (1995–1998) were followed for distant recurrence and breast cancer death. Clinicopathological parameters were collected from hospital records. The primary tumors were analyzed using the Prosigna® PAM50 assay to determine the prognostic value of the intrinsic subtypes and ROR score in comparison with pathological characteristics. The primary endpoints were distant disease-free survival (DDFS) and breast cancer-specific survival (BCSS). Results Of 653 tumors, 52.2% were classified as luminal A, 26.5% as luminal B, 10.6% as HER2-enriched, and 10.7% as basal-like. Among the HR+/HER2− patients (n = 476), 37.8% were categorized as low risk by ROR score, 22.7% as intermediate risk, and 39.5% as high risk. Median follow-up durations for BCSS and DDFS were 16.6 and 7.1 years, respectively. Multivariate analysis showed that intrinsic subtypes (all patients) and ROR risk classification (HR+/HER2− patients) yielded strong prognostic information. Among the HR+/HER2− pN0 patients with no adjuvant treatment (n = 231), 53.7% of patients had a low ROR, and their prognosis at 15 years was excellent (15-year BCSS 96.3%). Patients with intermediate risk had reduced survival compared with those with low risk (p = 0.005). In contrast, no difference in survival between the low- and intermediate-risk groups was seen for HR+/HER2− pN0 patients who received tamoxifen only. Ki-67 protein, grade, and ROR score were analyzed in the unselected, untreated pT1pN0 HR+/HER2− population (n = 171). In multivariate analysis, ROR score outperformed both Ki-67 and grade. Furthermore, 55% of patients who according to the PREDICT tool ( http://www.predict.nhs.uk/ ) would be considered chemotherapy candidates were ROR low risk (33%) or luminal A ROR intermediate risk (22%). Conclusions The PAM50 intrinsic subtype classification and ROR score improve classification of patients with breast cancer into prognostic groups, allowing for a more precise identification of future recurrence risk and providing an improved basis for adjuvant treatment decisions. Node-negative patients with low ROR scores had an excellent outcome at 15 years even in the absence of adjuvant therapy

β-Defensin genomic copy number does not influence the age of onset in Huntington's Disease

none498siHuntington's disease (HD) is an autosomal dominant neurodegenerative disorder caused by the abnormal expansion of a CAG triplet repeat tract in the huntingtin gene. While the length of this CAG expansion is the major determinant of the age of onset (AO), other genetic factors have also been shown to play a modulatory role. Recent evidence suggests that neuroinflammations is a pivotal factor in the pathogenesis of HD, and that targeting this process may have important therapeutic ramifications. The human β-defensin 2 (hBD2)- encoded by DEFB4- is an antimicrobial peptide that exhibits inducible expression in astrocytes during inflammation and is an important regulator of innate and adaptive immune response. Therefore, DEFB4 may contribute to the neuroinflammatory processes observed in HD.openVittori A, Orth M, Roos RA, Outeiro TF, Giorgini F, Hollox EJ, Bachoud-Levi AC, Bentivoglio AR, Biunno I, Bonelli RM, Burgunder JM, Dunnett SB, Ferreira JJ, Handley OJ, Heiberg A, Illmann T, Landwehrmeyer GB, Levey J, Martinez-Jaurrieta MD, Nielsen JE, Pro Koivisto S, Piiiviirinta M, Roos RA, Sebastian AR, Tabrizi SJ, Vandenberghe W, Verellen-Dumoulin C, Zaremba J, Uhrova T, Wahlstrom J, Barth K, Correia-Guedes L, Finisterra AM, Bascuiiana Garde M, Betz S, Bos R, Ecker D, Handley OJ, Held C, Koppers K, Laura M, Descals AM, Mestre T, Monza D, Townhill J, Padieu H, Paterski L, Peppa N, Rialland A, Røren N, Sasinkova P, Trigo Cubillo P, van Walsem M, Witjes-Ane MN, Yudina E, Zielonka D, Zielonka E, Zinzi P, Bonelli RM, Herranhof B, HOd A, Kapfhammer HP, Koppitz M, Magnet M, Otti D, Painold A, Reisinge K, Scheib M, Hecht K, Lilek S, Muller N, Schoggl H, Ullah J, Ribal P, Verellen-Dumoulin C, Klempff J, Majerova V, Roth J, Hjermind LE, Jakobsen O, Vinthev-Jensen T, Larsen IU, Nielsen JE, Stokholm J, Hiivola H, Martikainen K, Tuuha K, Santala M, Milkereit E, Kosinski CM, Probst D, Reetz K, Sass C, Schiefer J, Schlangen C, Werner CJ, Andrich J, Ellrichmann G, Hoffmann R, Kaminski B, Saft C, Stamm C, Lange H, Lohle M, Schmidt S, Storch A, Wolz A, Wolz M, Capetian P, Lambeck J, Zucker B, Boelmans K, Ganos C, Hidding U, Lewerenz J, Miinchau A, Orth M, Schmalfeld J, Stubbe L, Zittel S, Heinicke W, Ribbat M, Longinus B, Miihlau M, Peinemann A, Stiidtler M, Weindl A, Winkelmann J, Ziegler C, Bechtel N, Beckmann H, Bohlen S, Holzner E, Lange H, Reilmann R, Rohm S, Rumpf S, Schepers S, Dose M, Leythaeuser G, Marquard R, Raab T, Schrenk C, Schuierer M, Barth K, Buck A, Ecker D, Eschenbach C, Held C, Landwehrmeyer B, Lezius F, Nepper S, Niess A, Orth M, Schwenk D, Siissmuth S, Trautmann S, Weydt P, Cormio C, de Tommaso M, Sciruicchio V, Serpino C, Ghelli E, Ginestroni A, Bertini E, Massaro F, Mechi C, Paganini M, Piacentini S, Pradella S, Romoli AM, Sorbi S, Abbruzzese G, Ferrandes MB, Di Maria E, Ferrandes G, Mandich P, Marchese R, Di Donato S, Gellera C, Genitrini S, Mariotti C, Nanetti L, Monza D, Soliveri P, Tomasello C, De Michele G, DiMaio L, Massarelli M, Rinaldi C, Roca A, Rossi F, Russo CV, Salvatore E, Sorrentino P, Tucci T, De Nicola A, Elifani F, Petrollini M, Martino T, Lovo F, Squitieri F, Bentivoglio AR, Catalli C, Di Giacopo R, Fasano A, Frontali M, Guidubaldi A, Ialongo T, Jacopini G, Loria G, Piano C, Piccininni C, Quaranta D, Romano S, Soleti F, Spadaro M, Zinzi P, van Hout MS, van Vugt JP, de Weert A, Bolwijn JJ, Neurologie P, Dekker M, Neurologie P, Leenders KL, van Oostrom JC, Bos R, Dumas EM, Jurgens CK, van den Bogaard SJ, Roos RA, 't Hart EP, Kremer B, Verstappen CC, Heiberg A, van Walsem MR, Frich J, Aaserud O, Wehus R, Bjørgo K, Fannemel M, Gørvell P, Lorentzen E, Koivisto SP, Retterstøl L, Stokke B, Bjørnevoll I, Sando SB, Dziadkiewicz A, Nowak M, Robowski P, Sitek E, Slawek J, Soltan W, Szinwelski M, Blaszczyk M, Boczarska-Jedynak M, Ciach-Wysocka E, Gorzkowska A, Jasinska-Myga B, Opala G, Klodowska G, Stompel D, Ciach-Wysocka E, Banaszkiewicz K, Boewiriska D, Bojakowska-Jaremek K, Neurologii A, Dec M, Krawczyk M, Rudziriska M, Szczudlik A, Szczygiel E, Wasielewska A, Wojcik M, Wojcik M, Bryl A, Ciesielska A, Klimberg A, Marcinkowski J, Samara H, Sempolowicz J, Zielonka D, Janik P, Kalbarczyk A, Kwiecinski H, Jamrozik Z, Antczak J, Jachinska K, Krysa W, Rakowicz M, Richter P, Rola R, Ryglewicz D, Sienkiewicz-Jarosz H, Sulek A, Witkowski G, Zdzienicka E, Zaremba J, Zieora-Jakutowicz K, Coelho M, Correia-Guedes L, Ferreira JJ, Mestre T, Mendes T, Valadas A, Andrade C, Joao PS, Gago M, Garrett C, Joao PS, Guerra MR, Joao PS, Solis P, Herrera CD, Garcia PM, Cubo E, Mariscal N, Sanchez J, Barrero FJ, Alonso-Frech F, Perez MR, Fenollar M, Garda R, Rivera SV, Villanueva C, Alegre J, Bascuiiana M, Ventura MF, Ribas GG, Moreno JL, Cubillo PT, Rufz PJ, Frech FA, Dfaz J, Guerrero R, Dfaz J, Artiga MJ, Dfaz J, Sanchez V, Alcaraz LF, de Ia Arrixaca V, Manzanares S, de Ia Arrixaca V, Perea MF, Reinante G, Arrixaca Ia, Torres MM, Moreau LV, de Ia Arrixaca V, Barbera MA, Guia DB, Hernanz LC, Catena JL, Sebastian R, Ferrer PQ, Carruesco GT, Bas J, Busquets N, Calopa M, Buongiorno MT, Munoz E, Elorza MD, Lopez CD, Terol DS, Robert MF, Rufz BG, Casado AG, Martinez IH, Viladrich CM, Pons R, Roca E, Llesoy JR, Idiago JM, Vergara MR, Garcia SS, Riballo AV, Hoglund A, Palhagen SE, Paucar M, Sandstrom B, Svenningsson P, Reza-Soltani TW, Burgunder JM, Kaelin A, Romero I, Schupbach M, Stebler Y, Zaugg SW, Akhtar S, Crooks J, Curtis A, de Souza J, Rickards H, Wright J, Barker RA, Di Pietro A, Fisher K, Goodman AO, Hill S, Kershaw A, Mason S, O'Keefe D, Swain R, Guzman NV, Busse M, Butcher C, Clenaghan C, Dunnett S, Fullam R, Jones L, Jones U, Khalil H, Minster S, Owen M, Hunt S, Price K, Rosser A, Townhill J, Edwards M, Ho C, McGill M, Pearson P, Porteous M, Brockie P, Foster J, Johns N, McKenzie S, Rothery J, Thomas G, Yates S, Burrows L, Chu C, Fletcher A, Gallantrae D, Harding A, Hamer S, Kraus A, Laver F, Longthorpe M, Markova I, Raman A, Silva M, Thomson A, Wild S, Yardumian P, Hobson E, Jamieson S, Musgrave H, Rowett L, Toscano J, Wild S, Yardumian P, Clayton C, Dipple H, Middleton J, Patino D, Andrews T, Dougherty A, Kavalier F, Golding C, Laing H, Lashwood A, Robertson D, Ruddy D, Whaite A, Santhouse A, Andrews T, Bruno S, Doherty K, Lahiri N, Novak M, Patel A, Rosser E, Tabrizi S, Taylor R, Warner T, Wild E, Arran N, Bek J, Callaghan J, Craufurd D, Fullam R, Howard L, Hare M, Huson S, Johnson L, Jones M, Murphy H, Oughton E, Partington-Janes L, Rogers D, Snowden J, Sollom A, Stopford C, Thompson J, Trender-Gerhard I.Vittori, A; Orth, M; Roos, Ra; Outeiro, Tf; Giorgini, F; Hollox, Ej; Bachoud-Levi, Ac; Bentivoglio, Ar; Biunno, I; Bonelli, Rm; Burgunder, Jm; Dunnett, Sb; Ferreira, Jj; Handley, Oj; Heiberg, A; Illmann, T; Landwehrmeyer, Gb; Levey, J; Martinez-Jaurrieta, Md; Nielsen, Je; Pro Koivisto, S; Piiiviirinta, M; Roos, Ra; Sebastian, Ar; Tabrizi, Sj; Vandenberghe, W; Verellen-Dumoulin, C; Zaremba, J; Uhrova, T; Wahlstrom, J; Barth, K; Correia-Guedes, L; Finisterra, Am; Bascuiiana Garde, M; Betz, S; Bos, R; Ecker, D; Handley, Oj; Held, C; Koppers, K; Laura, M; Descals, Am; Mestre, T; Monza, D; Townhill, J; Padieu, H; Paterski, L; Peppa, N; Rialland, A; Røren, N; Sasinkova, P; Trigo Cubillo, P; van Walsem, M; Witjes-Ane, Mn; Yudina, E; Zielonka, D; Zielonka, E; Zinzi, P; Bonelli, Rm; Herranhof, B; Hod, A; Kapfhammer, Hp; Koppitz, M; Magnet, M; Otti, D; Painold, A; Reisinge, K; Scheib, M; Hecht, K; Lilek, S; Muller, N; Schoggl, H; Ullah, J; Ribal, P; Verellen-Dumoulin, C; Klempff, J; Majerova, V; Roth, J; Hjermind, Le; Jakobsen, O; Vinthev-Jensen, T; Larsen, Iu; Nielsen, Je; Stokholm, J; Hiivola, H; Martikainen, K; Tuuha, K; Santala, M; Milkereit, E; Kosinski, Cm; Probst, D; Reetz, K; Sass, C; Schiefer, J; Schlangen, C; Werner, Cj; Andrich, J; Ellrichmann, G; Hoffmann, R; Kaminski, B; Saft, C; Stamm, C; Lange, H; Lohle, M; Schmidt, S; Storch, A; Wolz, A; Wolz, M; Capetian, P; Lambeck, J; Zucker, B; Boelmans, K; Ganos, C; Hidding, U; Lewerenz, J; Miinchau, A; Orth, M; Schmalfeld, J; Stubbe, L; Zittel, S; Heinicke, W; Ribbat, M; Longinus, B; Miihlau, M; Peinemann, A; Stiidtler, M; Weindl, A; Winkelmann, J; Ziegler, C; Bechtel, N; Beckmann, H; Bohlen, S; Holzner, E; Lange, H; Reilmann, R; Rohm, S; Rumpf, S; Schepers, S; Dose, M; Leythaeuser, G; Marquard, R; Raab, T; Schrenk, C; Schuierer, M; Barth, K; Buck, A; Ecker, D; Eschenbach, C; Held, C; Landwehrmeyer, B; Lezius, F; Nepper, S; Niess, A; Orth, M; Schwenk, D; Siissmuth, S; Trautmann, S; Weydt, P; Cormio, C; de Tommaso, M; Sciruicchio, V; Serpino, C; Ghelli, E; Ginestroni, A; Bertini, E; Massaro, F; Mechi, C; Paganini, M; Piacentini, S; Pradella, S; Romoli, Am; Sorbi, S; Abbruzzese, G; Ferrandes, Mb; Di Maria, E; Ferrandes, G; Mandich, P; Marchese, R; Di Donato, S; Gellera, C; Genitrini, S; Mariotti, C; Nanetti, L; Monza, D; Soliveri, P; Tomasello, C; De Michele, G; Dimaio, L; Massarelli, M; Rinaldi, C; Roca, A; Rossi, F; Russo, Cv; Salvatore, E; Sorrentino, P; Tucci, T; De Nicola, A; Elifani, F; Petrollini, M; Martino, T; Lovo, F; Squitieri, F; Bentivoglio, Ar; Catalli, C; Di Giacopo, R; Fasano, A; Frontali, M; Guidubaldi, A; Ialongo, T; Jacopini, G; Loria, G; Piano, C; Piccininni, C; Quaranta, D; Romano, S; Soleti, F; Spadaro, M; Zinzi, P; van Hout, Ms; van Vugt, Jp; de Weert, A; Bolwijn, Jj; Neurologie, P; Dekker, M; Neurologie, P; Leenders, Kl; van Oostrom, Jc; Bos, R; Dumas, Em; Jurgens, Ck; van den Bogaard, Sj; Roos, Ra; 't Hart, Ep; Kremer, B; Verstappen, Cc; Heiberg, A; van Walsem, Mr; Frich, J; Aaserud, O; Wehus, R; Bjørgo, K; Fannemel, M; Gørvell, P; Lorentzen, E; Koivisto, Sp; Retterstøl, L; Stokke, B; Bjørnevoll, I; Sando, Sb; Dziadkiewicz, A; Nowak, M; Robowski, P; Sitek, E; Slawek, J; Soltan, W; Szinwelski, M; Blaszczyk, M; Boczarska-Jedynak, M; Ciach-Wysocka, E; Gorzkowska, A; Jasinska-Myga, B; Opala, G; Klodowska, G; Stompel, D; Ciach-Wysocka, E; Banaszkiewicz, K; Boewiriska, D; Bojakowska-Jaremek, K; Neurologii, A; Dec, M; Krawczyk, M; Rudziriska, M; Szczudlik, A; Szczygiel, E; Wasielewska, A; Wojcik, M; Wojcik, M; Bryl, A; Ciesielska, A; Klimberg, A; Marcinkowski, J; Samara, H; Sempolowicz, J; Zielonka, D; Janik, P; Kalbarczyk, A; Kwiecinski, H; Jamrozik, Z; Antczak, J; Jachinska, K; Krysa, W; Rakowicz, M; Richter, P; Rola, R; Ryglewicz, D; Sienkiewicz-Jarosz, H; Sulek, A; Witkowski, G; Zdzienicka, E; Zaremba, J; Zieora-Jakutowicz, K; Coelho, M; Correia-Guedes, L; Ferreira, Jj; Mestre, T; Mendes, T; Valadas, A; Andrade, C; Joao, Ps; Gago, M; Garrett, C; Joao, Ps; Guerra, Mr; Joao, Ps; Solis, P; Herrera, Cd; Garcia, Pm; Cubo, E; Mariscal, N; Sanchez, J; Barrero, Fj; Alonso-Frech, F; Perez, Mr; Fenollar, M; Garda, R; Rivera, Sv; Villanueva, C; Alegre, J; Bascuiiana, M; Ventura, Mf; Ribas, Gg; Moreno, Jl; Cubillo, Pt; Rufz, Pj; Frech, Fa; Dfaz, J; Guerrero, R; Dfaz, J; Artiga, Mj; Dfaz, J; Sanchez, V; Alcaraz, Lf; de Ia Arrixaca, V; Manzanares, S; de Ia Arrixaca, V; Perea, Mf; Reinante, G; Arrixaca, Ia; Torres, Mm; Moreau, Lv; de Ia Arrixaca, V; Barbera, Ma; Guia, Db; Hernanz, Lc; Catena, Jl; Sebastian, R; Ferrer, Pq; Carruesco, Gt; Bas, J; Busquets, N; Calopa, M; Buongiorno, Mt; Munoz, E; Elorza, Md; Lopez, Cd; Terol, Ds; Robert, Mf; Rufz, Bg; Casado, Ag; Martinez, Ih; Viladrich, Cm; Pons, R; Roca, E; Llesoy, Jr; Idiago, Jm; Vergara, Mr; Garcia, Ss; Riballo, Av; Hoglund, A; Palhagen, Se; Paucar, M; Sandstrom, B; Svenningsson, P; Reza-Soltani, Tw; Burgunder, Jm; Kaelin, A; Romero, I; Schupbach, M; Stebler, Y; Zaugg, Sw; Akhtar, S; Crooks, J; Curtis, A; de Souza, J; Rickards, H; Wright, J; Barker, Ra; Di Pietro, A; Fisher, K; Goodman, Ao; Hill, S; Kershaw, A; Mason, S; O'Keefe, D; Swain, R; Guzman, Nv; Busse, M; Butcher, C; Clenaghan, C; Dunnett, S; Fullam, R; Jones, L; Jones, U; Khalil, H; Minster, S; Owen, M; Hunt, S; Price, K; Rosser, A; Townhill, J; Edwards, M; Ho, C; Mcgill, M; Pearson, P; Porteous, M; Brockie, P; Foster, J; Johns, N; Mckenzie, S; Rothery, J; Thomas, G; Yates, S; Burrows, L; Chu, C; Fletcher, A; Gallantrae, D; Harding, A; Hamer, S; Kraus, A; Laver, F; Longthorpe, M; Markova, I; Raman, A; Silva, M; Thomson, A; Wild, S; Yardumian, P; Hobson, E; Jamieson, S; Musgrave, H; Rowett, L; Toscano, J; Wild, S; Yardumian, P; Clayton, C; Dipple, H; Middleton, J; Patino, D; Andrews, T; Dougherty, A; Kavalier, F; Golding, C; Laing, H; Lashwood, A; Robertson, D; Ruddy, D; Whaite, A; Santhouse, A; Andrews, T; Bruno, S; Doherty, K; Lahiri, N; Novak, M; Patel, A; Rosser, E; Tabrizi, S; Taylor, R; Warner, T; Wild, E; Arran, N; Bek, J; Callaghan, J; Craufurd, D; Fullam, R; Howard, L; Hare, M; Huson, S; Johnson, L; Jones, M; Murphy, H; Oughton, E; Partington-Janes, L; Rogers, D; Snowden, J; Sollom, A; Stopford, C; Thompson, J; Trender-Gerhard, I

Discrepancies in reporting the CAG repeat lengths for Huntington's disease.

Huntington's disease results from a CAG repeat expansion within the Huntingtin gene; this is measured routinely in diagnostic laboratories. The European Huntington's Disease Network REGISTRY project centrally measures CAG repeat lengths on fresh samples; these were compared with the original results from 121 laboratories across 15 countries. We report on 1326 duplicate results; a discrepancy in reporting the upper allele occurred in 51% of cases, this reduced to 13.3% and 9.7% when we applied acceptable measurement errors proposed by the American College of Medical Genetics and the Draft European Best Practice Guidelines, respectively. Duplicate results were available for 1250 lower alleles; discrepancies occurred in 40% of cases. Clinically significant discrepancies occurred in 4.0% of cases with a potential unexplained misdiagnosis rate of 0.3%. There was considerable variation in the discrepancy rate among 10 of the countries participating in this study. Out of 1326 samples, 348 were re-analysed by an accredited diagnostic laboratory, based in Germany, with concordance rates of 93% and 94% for the upper and lower alleles, respectively. This became 100% if the acceptable measurement errors were applied. The central laboratory correctly reported allele sizes for six standard reference samples, blind to the known result. Our study differs from external quality assessment (EQA) schemes in that these are duplicate results obtained from a large sample of patients across the whole diagnostic range. We strongly recommend that laboratories state an error rate for their measurement on the report, participate in EQA schemes and use reference materials regularly to adjust their own internal standards