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author:("beutin, Peter")
1.  A pathway-based analysis provides additional support for an immune-related genetic susceptibility to Parkinson's disease 
Holmans, Peter | Moskvina, Valentina | Jones, Lesley | Sharma, Manu | Vedernikov, Alexey | Buchel, Finja | Sadd, Mohamad | Bras, Jose M. | Bettella, Francesco | Nicolaou, Nayia | Simón-Sánchez, Javier | Mittag, Florian | Gibbs, J. Raphael | Schulte, Claudia | Durr, Alexandra | Guerreiro, Rita | Hernandez, Dena | Brice, Alexis | Stefánsson, Hreinn | Majamaa, Kari | Gasser, Thomas | Heutink, Peter | Wood, Nicholas W. | Martinez, Maria | Singleton, Andrew B. | Nalls, Michael A. | Hardy, John | Morris, Huw R. | Williams, Nigel M. | Arepalli, Sampath | Barker, Roger | Barrett, Jeffrey | Ben-Shlomo, Yoav | Berendse, Henk W. | Berg, Daniela | Bhatia, Kailash | de Bie, Rob M.A. | Biffi, Alessandro | Bloem, Bas | Brice, Alexis | Bochdanovits, Zoltan | Bonin, Michael | Bras, Jose M. | Brockmann, Kathrin | Brooks, Janet | Burn, David J. | Charlesworth, Gavin | Chen, Honglei | Chinnery, Patrick F. | Chong, Sean | Clarke, Carl E. | Cookson, Mark R. | Cooper, Jonathan M. | Corvol, Jen-Christophe | Counsell, Carl | Damier, Philippe | Dartigues, Jean Francois | Deloukas, Panagiotis | Deuschl, Günther | Dexter, David T. | van Dijk, Karin D. | Dillman, Allissa | Durif, Frank | Durr, Alexandra | Edkins, Sarah | Evans, Jonathan R. | Foltynie, Thomas | Gao, Jianjun | Gardner, Michelle | Gasser, Thomas | Gibbs, J. Raphael | Goate, Alison | Gray, Emma | Guerreiro, Rita | Gústafsson, Ómar | Hardy, John | Harris, Clare | Hernandez, Dena G. | Heutink, Peter | van Hilten, Jacobus J. | Hofman, Albert | Hollenbeck, Albert | Holmans, Peter | Holton, Janice | Hu, Michele | Huber, Heiko | Hudson, Gavin | Hunt, Sarah E. | Huttenlocher, Johanna | Illig, Thomas | Langford, Cordelia | Lees, Andrew | Lesage, Suzanne | Lichtner, Peter | Limousin, Patricia | Lopez, Grisel | Lorenz, Delia | Martinez, Maria | McNeill, Alisdair | Moorby, Catriona | Moore, Matthew | Morris, Huw | Morrison, Karen E. | Moskvina, Valentina | Mudanohwo, Ese | Nalls, Michael A. | Pearson, Justin | Perlmutter, Joel S. | Pétursson, Hjörvar | Plagnol, Vincent | Pollak, Pierre | Post, Bart | Potter, Simon | Ravina, Bernard | Revesz, Tamas | Riess, Olaf | Rivadeneira, Fernando | Rizzu, Patrizia | Ryten, Mina | Saad, Mohamad | Sawcer, Stephen | Schapira, Anthony | Scheffer, Hans | Sharma, Manu | Shaw, Karen | Sheerin, Una-Marie | Shoulson, Ira | Schulte, Claudia | Sidransky, Ellen | Simón-Sánchez, Javier | Singleton, Andrew B. | Smith, Colin | Stefánsson, Hreinn | Stefánsson, Kári | Steinberg, Stacy | Stockton, Joanna D. | Sveinbjornsdottir, Sigurlaug | Talbot, Kevin | Tanner, Carlie M. | Tashakkori-Ghanbaria, Avazeh | Tison, François | Trabzuni, Daniah | Traynor, Bryan J. | Uitterlinden, André G. | Velseboer, Daan | Vidailhet, Marie | Walker, Robert | van de Warrenburg, Bart | Wickremaratchi, Mirdhu | Williams, Nigel | Williams-Gray, Caroline H. | Winder-Rhodes, Sophie | Wood, Nicholas
Human Molecular Genetics  2012;22(5):1039-1049.
Parkinson's disease (PD) is the second most common neurodegenerative disease affecting 1–2% in people >60 and 3–4% in people >80. Genome-wide association (GWA) studies have now implicated significant evidence for association in at least 18 genomic regions. We have studied a large PD-meta analysis and identified a significant excess of SNPs (P < 1 × 10−16) that are associated with PD but fall short of the genome-wide significance threshold. This result was independent of variants at the 18 previously implicated regions and implies the presence of additional polygenic risk alleles. To understand how these loci increase risk of PD, we applied a pathway-based analysis, testing for biological functions that were significantly enriched for genes containing variants associated with PD. Analysing two independent GWA studies, we identified that both had a significant excess in the number of functional categories enriched for PD-associated genes (minimum P = 0.014 and P = 0.006, respectively). Moreover, 58 categories were significantly enriched for associated genes in both GWA studies (P < 0.001), implicating genes involved in the ‘regulation of leucocyte/lymphocyte activity’ and also ‘cytokine-mediated signalling’ as conferring an increased susceptibility to PD. These results were unaltered by the exclusion of all 178 genes that were present at the 18 genomic regions previously reported to be strongly associated with PD (including the HLA locus). Our findings, therefore, provide independent support to the strong association signal at the HLA locus and imply that the immune-related genetic susceptibility to PD is likely to be more widespread in the genome than previously appreciated.
doi:10.1093/hmg/dds492
PMCID: PMC3561909  PMID: 23223016
3.  Genome-wide Association Study of Obsessive-Compulsive Disorder 
Stewart, S Evelyn | Yu, Dongmei | Scharf, Jeremiah M | Neale, Benjamin M | Fagerness, Jesen A | Mathews, Carol A | Arnold, Paul D | Evans, Patrick D | Gamazon, Eric R | Osiecki, Lisa | McGrath, Lauren | Haddad, Stephen | Crane, Jacquelyn | Hezel, Dianne | Illman, Cornelia | Mayerfeld, Catherine | Konkashbaev, Anuar | Liu, Chunyu | Pluzhnikov, Anna | Tikhomirov, Anna | Edlund, Christopher K | Rauch, Scott L | Moessner, Rainald | Falkai, Peter | Maier, Wolfgang | Ruhrmann, Stephan | Grabe, Hans-Jörgen | Lennertz, Leonard | Wagner, Michael | Bellodi, Laura | Cavallini, Maria Cristina | Richter, Margaret A | Cook, Edwin H | Kennedy, James L | Rosenberg, David | Stein, Dan J | Hemmings, Sian MJ | Lochner, Christine | Azzam, Amin | Chavira, Denise A | Fournier, Eduardo | Garrido, Helena | Sheppard, Brooke | Umaña, Paul | Murphy, Dennis L | Wendland, Jens R | Veenstra-VanderWeele, Jeremy | Denys, Damiaan | Blom, Rianne | Deforce, Dieter | Van Nieuwerburgh, Filip | Westenberg, Herman GM | Walitza, Susanne | Egberts, Karin | Renner, Tobias | Miguel, Euripedes Constantino | Cappi, Carolina | Hounie, Ana G | Conceição do Rosário, Maria | Sampaio, Aline S | Vallada, Homero | Nicolini, Humberto | Lanzagorta, Nuria | Camarena, Beatriz | Delorme, Richard | Leboyer, Marion | Pato, Carlos N | Pato, Michele T | Voyiaziakis, Emanuel | Heutink, Peter | Cath, Danielle C | Posthuma, Danielle | Smit, Jan H | Samuels, Jack | Bienvenu, O Joseph | Cullen, Bernadette | Fyer, Abby J | Grados, Marco A | Greenberg, Benjamin D | McCracken, James T | Riddle, Mark A | Wang, Ying | Coric, Vladimir | Leckman, James F | Bloch, Michael | Pittenger, Christopher | Eapen, Valsamma | Black, Donald W | Ophoff, Roel A | Strengman, Eric | Cusi, Daniele | Turiel, Maurizio | Frau, Francesca | Macciardi, Fabio | Gibbs, J Raphael | Cookson, Mark R | Singleton, Andrew | Hardy, John | Crenshaw, Andrew T | Parkin, Melissa A | Mirel, Daniel B | Conti, David V | Purcell, Shaun | Nestadt, Gerald | Hanna, Gregory L | Jenike, Michael A | Knowles, James A | Cox, Nancy | Pauls, David L
Molecular psychiatry  2012;18(7):788-798.
Obsessive-compulsive disorder (OCD) is a common, debilitating neuropsychiatric illness with complex genetic etiology. The International OCD Foundation Genetics Collaborative (IOCDF-GC) is a multi-national collaboration established to discover the genetic variation predisposing to OCD. A set of individuals affected with DSM-IV OCD, a subset of their parents, and unselected controls, were genotyped with several different Illumina SNP microarrays. After extensive data cleaning, 1,465 cases, 5,557 ancestry-matched controls and 400 complete trios remained, with a common set of 469,410 autosomal and 9,657 X-chromosome SNPs. Ancestry-stratified case-control association analyses were conducted for three genetically-defined subpopulations and combined in two meta-analyses, with and without the trio-based analysis. In the case-control analysis, the lowest two p-values were located within DLGAP1 (p=2.49×10-6 and p=3.44×10-6), a member of the neuronal postsynaptic density complex. In the trio analysis, rs6131295, near BTBD3, exceeded the genome-wide significance threshold with a p-value=3.84 × 10-8. However, when trios were meta-analyzed with the combined case-control samples, the p-value for this variant was 3.62×10-5, losing genome-wide significance. Although no SNPs were identified to be associated with OCD at a genome-wide significant level in the combined trio-case-control sample, a significant enrichment of methylation-QTLs (p<0.001) and frontal lobe eQTLs (p=0.001) was observed within the top-ranked SNPs (p<0.01) from the trio-case-control analysis, suggesting these top signals may have a broad role in gene expression in the brain, and possibly in the etiology of OCD.
doi:10.1038/mp.2012.85
PMCID: PMC4218751  PMID: 22889921
Obsessive-compulsive disorder; GWAS; Genetic; Genomic; Neurodevelopmental disorder; DLGAP
4.  Genetic comorbidities in Parkinson’s disease 
Human molecular genetics  2013;23(3):831-841.
Parkinson’s disease (PD) has a number of known genetic risk factors. Clinical and epidemiological studies have suggested the existence of intermediate factors that may be associated with additional risk of PD. We construct genetic risk profiles for additional epidemiological and clinical factors using known genome-wide association studies (GWAS) loci related to these specific phenotypes to estimate genetic comorbidity in a systematic review. We identify genetic risk profiles based on GWAS variants associated with schizophrenia and Crohn’s disease as significantly associated with risk of PD. Conditional analyses adjusting for SNPs near loci associated with PD and schizophrenia or PD and Crohn’s disease suggest that spatially overlapping loci associated with schizophrenia and PD account for most of the shared comorbidity, while variation outside of known proximal loci shared by PD and Crohn’s disease accounts for their shared genetic comorbidity. We examine brain methylation and expression signatures proximal to schizophrenia and Crohn’s disease loci to infer functional changes in the brain associated with the variants contributing to genetic comorbidity. We compare our results with a systematic review of epidemiological literature, while the findings are dissimilar to a degree; marginal genetic associations corroborate the directionality of associations across genetic and epidemiological data. We show a strong genetically defined level of comorbidity between PD and Crohn’s disease as well as between PD and schizophrenia, with likely functional consequences of associated variants occurring in brain.
doi:10.1093/hmg/ddt465
PMCID: PMC3888265  PMID: 24057672
5.  Trehalose Improves Human Fibroblast Deficits in a New CHIP-Mutation Related Ataxia 
PLoS ONE  2014;9(9):e106931.
In this work we investigate the role of CHIP in a new CHIP-mutation related ataxia and the therapeutic potential of trehalose. The patient's fibroblasts with a new form of hereditary ataxia, related to STUB1 gene (CHIP) mutations, and three age and sex-matched controls were treated with epoxomicin and trehalose. The effects on cell death, protein misfolding and proteostasis were evaluated. Recent studies have revealed that mutations in STUB-1 gene lead to a growing list of molecular defects as deregulation of protein quality, inhibition of proteasome, cell death, decreased autophagy and alteration in CHIP and HSP70 levels. In this CHIP-mutant patient fibroblasts the inhibition of proteasome with epoxomicin induced severe pathophysiological age-associated changes, cell death and protein ubiquitination. Additionally, treatment with epoxomicin produced a dose-dependent increase in the number of cleaved caspase-3 positive cells. However, co-treatment with trehalose, a disaccharide of glucose present in a wide variety of organisms and known as a autophagy enhancer, reduced these pathological events. Trehalose application also increased CHIP and HSP70 expression and GSH free radical levels. Furthermore, trehalose augmented macro and chaperone mediated autophagy (CMA), rising the levels of LC3, LAMP2, CD63 and increasing the expression of Beclin-1 and Atg5-Atg12. Trehalose treatment in addition increased the percentage of immunoreactive cells to HSC70 and LAMP2 and reduced the autophagic substrate, p62. Although this is an individual case based on only one patient and the statistical comparisons are not valid between controls and patient, the low variability among controls and the obvious differences with this patient allow us to conclude that trehalose, through its autophagy activation capacity, anti-aggregation properties, anti-oxidative effects and lack of toxicity, could be very promising for the treatment of CHIP-mutation related ataxia, and possibly a wide spectrum of neurodegenerative disorders related to protein disconformation.
doi:10.1371/journal.pone.0106931
PMCID: PMC4178022  PMID: 25259530
6.  Parkinson’s disease in GTP cyclohydrolase 1 mutation carriers 
Brain  2014;137(9):2480-2492.
Mutations in the gene encoding the dopamine-synthetic enzyme GTP cyclohydrolase-1 (GCH1) cause DOPA-responsive dystonia (DRD). Mencacci et al. demonstrate that GCH1 variants are associated with an increased risk of Parkinson's disease in both DRD pedigrees and in patients with Parkinson's disease but without a family history of DRD.
GTP cyclohydrolase 1, encoded by the GCH1 gene, is an essential enzyme for dopamine production in nigrostriatal cells. Loss-of-function mutations in GCH1 result in severe reduction of dopamine synthesis in nigrostriatal cells and are the most common cause of DOPA-responsive dystonia, a rare disease that classically presents in childhood with generalized dystonia and a dramatic long-lasting response to levodopa. We describe clinical, genetic and nigrostriatal dopaminergic imaging ([123I]N-ω-fluoropropyl-2β-carbomethoxy-3β-(4-iodophenyl) tropane single photon computed tomography) findings of four unrelated pedigrees with DOPA-responsive dystonia in which pathogenic GCH1 variants were identified in family members with adult-onset parkinsonism. Dopamine transporter imaging was abnormal in all parkinsonian patients, indicating Parkinson’s disease-like nigrostriatal dopaminergic denervation. We subsequently explored the possibility that pathogenic GCH1 variants could contribute to the risk of developing Parkinson’s disease, even in the absence of a family history for DOPA-responsive dystonia. The frequency of GCH1 variants was evaluated in whole-exome sequencing data of 1318 cases with Parkinson’s disease and 5935 control subjects. Combining cases and controls, we identified a total of 11 different heterozygous GCH1 variants, all at low frequency. This list includes four pathogenic variants previously associated with DOPA-responsive dystonia (Q110X, V204I, K224R and M230I) and seven of undetermined clinical relevance (Q110E, T112A, A120S, D134G, I154V, R198Q and G217V). The frequency of GCH1 variants was significantly higher (Fisher’s exact test P-value 0.0001) in cases (10/1318 = 0.75%) than in controls (6/5935 = 0.1%; odds ratio 7.5; 95% confidence interval 2.4–25.3). Our results show that rare GCH1 variants are associated with an increased risk for Parkinson’s disease. These findings expand the clinical and biological relevance of GTP cycloydrolase 1 deficiency, suggesting that it not only leads to biochemical striatal dopamine depletion and DOPA-responsive dystonia, but also predisposes to nigrostriatal cell loss. Further insight into GCH1-associated pathogenetic mechanisms will shed light on the role of dopamine metabolism in nigral degeneration and Parkinson’s disease.
doi:10.1093/brain/awu179
PMCID: PMC4132650  PMID: 24993959
GCH1; DOPA-responsive-dystonia; Parkinson’s disease; dopamine; exome sequencing
7.  NUBPL mutations in patients with complex I deficiency and a distinct MRI pattern 
Neurology  2013;80(17):1577-1583.
Objective:
To identify the mutated gene in a group of patients with an unclassified heritable white matter disorder sharing the same, distinct MRI pattern.
Methods:
We used MRI pattern recognition analysis to select a group of patients with a similar, characteristic MRI pattern. We performed whole-exome sequencing to identify the mutated gene. We examined patients' fibroblasts for biochemical consequences of the mutant protein.
Results:
We identified 6 patients from 5 unrelated families with a similar MRI pattern showing predominant abnormalities of the cerebellar cortex, deep cerebral white matter, and corpus callosum. The 4 tested patients had a respiratory chain complex І deficiency. Exome sequencing revealed mutations in NUBPL, encoding an iron-sulfur cluster assembly factor for complex І, in all patients. Upon identification of the mutated gene, we analyzed the MRI of a previously published case with NUBPL mutations and found exactly the same pattern. A strongly decreased amount of NUBPL protein and fully assembled complex I was found in patients' fibroblasts. Analysis of the effect of mutated NUBPL on the assembly of the peripheral arm of complex I indicated that NUBPL is involved in assembly of iron-sulfur clusters early in the complex I assembly pathway.
Conclusion:
Our data show that NUBPL mutations are associated with a unique, consistent, and recognizable MRI pattern, which facilitates fast diagnosis and obviates the need for other tests, including assessment of mitochondrial complex activities in muscle or fibroblasts.
doi:10.1212/WNL.0b013e31828f1914
PMCID: PMC3662327  PMID: 23553477
10.  Genome-wide association study of Tourette Syndrome 
Scharf, Jeremiah M. | Yu, Dongmei | Mathews, Carol A. | Neale, Benjamin M. | Stewart, S. Evelyn | Fagerness, Jesen A | Evans, Patrick | Gamazon, Eric | Edlund, Christopher K. | Service, Susan | Tikhomirov, Anna | Osiecki, Lisa | Illmann, Cornelia | Pluzhnikov, Anna | Konkashbaev, Anuar | Davis, Lea K | Han, Buhm | Crane, Jacquelyn | Moorjani, Priya | Crenshaw, Andrew T. | Parkin, Melissa A. | Reus, Victor I. | Lowe, Thomas L. | Rangel-Lugo, Martha | Chouinard, Sylvain | Dion, Yves | Girard, Simon | Cath, Danielle C | Smit, Jan H | King, Robert A. | Fernandez, Thomas | Leckman, James F. | Kidd, Kenneth K. | Kidd, Judith R. | Pakstis, Andrew J. | State, Matthew | Herrera, Luis Diego | Romero, Roxana | Fournier, Eduardo | Sandor, Paul | Barr, Cathy L | Phan, Nam | Gross-Tsur, Varda | Benarroch, Fortu | Pollak, Yehuda | Budman, Cathy L. | Bruun, Ruth D. | Erenberg, Gerald | Naarden, Allan L | Lee, Paul C | Weiss, Nicholas | Kremeyer, Barbara | Berrío, Gabriel Bedoya | Campbell, Desmond | Silgado, Julio C. Cardona | Ochoa, William Cornejo | Restrepo, Sandra C. Mesa | Muller, Heike | Duarte, Ana V. Valencia | Lyon, Gholson J | Leppert, Mark | Morgan, Jubel | Weiss, Robert | Grados, Marco A. | Anderson, Kelley | Davarya, Sarah | Singer, Harvey | Walkup, John | Jankovic, Joseph | Tischfield, Jay A. | Heiman, Gary A. | Gilbert, Donald L. | Hoekstra, Pieter J. | Robertson, Mary M. | Kurlan, Roger | Liu, Chunyu | Gibbs, J. Raphael | Singleton, Andrew | Hardy, John | Strengman, Eric | Ophoff, Roel | Wagner, Michael | Moessner, Rainald | Mirel, Daniel B. | Posthuma, Danielle | Sabatti, Chiara | Eskin, Eleazar | Conti, David V. | Knowles, James A. | Ruiz-Linares, Andres | Rouleau, Guy A. | Purcell, Shaun | Heutink, Peter | Oostra, Ben A. | McMahon, William | Freimer, Nelson | Cox, Nancy J. | Pauls, David L.
Molecular psychiatry  2012;18(6):721-728.
Tourette Syndrome (TS) is a developmental disorder that has one of the highest familial recurrence rates among neuropsychiatric diseases with complex inheritance. However, the identification of definitive TS susceptibility genes remains elusive. Here, we report the first genome-wide association study (GWAS) of TS in 1285 cases and 4964 ancestry-matched controls of European ancestry, including two European-derived population isolates, Ashkenazi Jews from North America and Israel, and French Canadians from Quebec, Canada. In a primary meta-analysis of GWAS data from these European ancestry samples, no markers achieved a genome-wide threshold of significance (p<5 × 10−8); the top signal was found in rs7868992 on chromosome 9q32 within COL27A1 (p=1.85 × 10−6). A secondary analysis including an additional 211 cases and 285 controls from two closely-related Latin-American population isolates from the Central Valley of Costa Rica and Antioquia, Colombia also identified rs7868992 as the top signal (p=3.6 × 10−7 for the combined sample of 1496 cases and 5249 controls following imputation with 1000 Genomes data). This study lays the groundwork for the eventual identification of common TS susceptibility variants in larger cohorts and helps to provide a more complete understanding of the full genetic architecture of this disorder.
doi:10.1038/mp.2012.69
PMCID: PMC3605224  PMID: 22889924
Tourette Syndrome; tics; genetics; GWAS; neurodevelopmental disorder
11.  Resequencing Three Candidate Genes for Major Depressive Disorder in a Dutch Cohort 
PLoS ONE  2013;8(11):e79921.
Major depressive disorder (MDD) is a psychiatric disorder, characterized by periods of low mood of more than two weeks, loss of interest in normally enjoyable activities and behavioral changes. MDD is a complex disorder and does not have a single genetic cause. In 2009 a genome wide association study (GWAS) was performed on the Dutch GAIN-MDD cohort. Many of the top signals of this GWAS mapped to a region spanning the gene PCLO, and the non-synonymous coding single nucleotide polymorphism (SNP) rs2522833 in the PCLO gene became genome wide significant after post-hoc analysis. We performed resequencing of PCLO, GRM7, and SLC6A4 in 50 control samples from the GAIN-MDD cohort, to detect new genomic variants. Subsequently, we genotyped these variants in the entire GAIN-MDD cohort and performed association analysis to investigate if rs2522833 is the causal variant or simply in linkage disequilibrium with a more associated variant. GRM7 and SLC6A4 are both candidate genes for MDD from literature. We aimed to gather more evidence that rs2522833 is indeed the causal variant in the GAIN-MDD cohort or to find a previously undetected common variant in either PCLO, GRM7, or SLC6A4 with a higher association in this cohort. After next generation sequencing and association analysis we excluded the possibility of an undetected common variant to be more associated. For neither PCLO nor GRM7 we found a more associated variant. For SLC6A4, we found a new SNP that showed a lower P-value (P = 0.07) than in the GAIN-MDD GWAS (P = 0.09). However, no evidence for genome-wide significance was found. Although we did not take into account rare variants, we conclude that our results provide further support for the hypothesis that the non-synonymous coding SNP rs2522833 in the PCLO gene is indeed likely to be the causal variant in the GAIN-MDD cohort.
doi:10.1371/journal.pone.0079921
PMCID: PMC3836783  PMID: 24278217
12.  Using genome-wide complex trait analysis to quantify ‘missing heritability’ in Parkinson's disease 
Human Molecular Genetics  2012;21(22):4996-5009.
Genome-wide association studies (GWASs) have been successful at identifying single-nucleotide polymorphisms (SNPs) highly associated with common traits; however, a great deal of the heritable variation associated with common traits remains unaccounted for within the genome. Genome-wide complex trait analysis (GCTA) is a statistical method that applies a linear mixed model to estimate phenotypic variance of complex traits explained by genome-wide SNPs, including those not associated with the trait in a GWAS. We applied GCTA to 8 cohorts containing 7096 case and 19 455 control individuals of European ancestry in order to examine the missing heritability present in Parkinson's disease (PD). We meta-analyzed our initial results to produce robust heritability estimates for PD types across cohorts. Our results identify 27% (95% CI 17–38, P = 8.08E − 08) phenotypic variance associated with all types of PD, 15% (95% CI −0.2 to 33, P = 0.09) phenotypic variance associated with early-onset PD and 31% (95% CI 17–44, P = 1.34E − 05) phenotypic variance associated with late-onset PD. This is a substantial increase from the genetic variance identified by top GWAS hits alone (between 3 and 5%) and indicates there are substantially more risk loci to be identified. Our results suggest that although GWASs are a useful tool in identifying the most common variants associated with complex disease, a great deal of common variants of small effect remain to be discovered.
doi:10.1093/hmg/dds335
PMCID: PMC3576713  PMID: 22892372
13.  Partitioning the Heritability of Tourette Syndrome and Obsessive Compulsive Disorder Reveals Differences in Genetic Architecture 
Davis, Lea K. | Yu, Dongmei | Keenan, Clare L. | Gamazon, Eric R. | Konkashbaev, Anuar I. | Derks, Eske M. | Neale, Benjamin M. | Yang, Jian | Lee, S. Hong | Evans, Patrick | Barr, Cathy L. | Bellodi, Laura | Benarroch, Fortu | Berrio, Gabriel Bedoya | Bienvenu, Oscar J. | Bloch, Michael H. | Blom, Rianne M. | Bruun, Ruth D. | Budman, Cathy L. | Camarena, Beatriz | Campbell, Desmond | Cappi, Carolina | Cardona Silgado, Julio C. | Cath, Danielle C. | Cavallini, Maria C. | Chavira, Denise A. | Chouinard, Sylvain | Conti, David V. | Cook, Edwin H. | Coric, Vladimir | Cullen, Bernadette A. | Deforce, Dieter | Delorme, Richard | Dion, Yves | Edlund, Christopher K. | Egberts, Karin | Falkai, Peter | Fernandez, Thomas V. | Gallagher, Patience J. | Garrido, Helena | Geller, Daniel | Girard, Simon L. | Grabe, Hans J. | Grados, Marco A. | Greenberg, Benjamin D. | Gross-Tsur, Varda | Haddad, Stephen | Heiman, Gary A. | Hemmings, Sian M. J. | Hounie, Ana G. | Illmann, Cornelia | Jankovic, Joseph | Jenike, Michael A. | Kennedy, James L. | King, Robert A. | Kremeyer, Barbara | Kurlan, Roger | Lanzagorta, Nuria | Leboyer, Marion | Leckman, James F. | Lennertz, Leonhard | Liu, Chunyu | Lochner, Christine | Lowe, Thomas L. | Macciardi, Fabio | McCracken, James T. | McGrath, Lauren M. | Mesa Restrepo, Sandra C. | Moessner, Rainald | Morgan, Jubel | Muller, Heike | Murphy, Dennis L. | Naarden, Allan L. | Ochoa, William Cornejo | Ophoff, Roel A. | Osiecki, Lisa | Pakstis, Andrew J. | Pato, Michele T. | Pato, Carlos N. | Piacentini, John | Pittenger, Christopher | Pollak, Yehuda | Rauch, Scott L. | Renner, Tobias J. | Reus, Victor I. | Richter, Margaret A. | Riddle, Mark A. | Robertson, Mary M. | Romero, Roxana | Rosàrio, Maria C. | Rosenberg, David | Rouleau, Guy A. | Ruhrmann, Stephan | Ruiz-Linares, Andres | Sampaio, Aline S. | Samuels, Jack | Sandor, Paul | Sheppard, Brooke | Singer, Harvey S. | Smit, Jan H. | Stein, Dan J. | Strengman, E. | Tischfield, Jay A. | Valencia Duarte, Ana V. | Vallada, Homero | Van Nieuwerburgh, Filip | Veenstra-VanderWeele, Jeremy | Walitza, Susanne | Wang, Ying | Wendland, Jens R. | Westenberg, Herman G. M. | Shugart, Yin Yao | Miguel, Euripedes C. | McMahon, William | Wagner, Michael | Nicolini, Humberto | Posthuma, Danielle | Hanna, Gregory L. | Heutink, Peter | Denys, Damiaan | Arnold, Paul D. | Oostra, Ben A. | Nestadt, Gerald | Freimer, Nelson B. | Pauls, David L. | Wray, Naomi R. | Stewart, S. Evelyn | Mathews, Carol A. | Knowles, James A. | Cox, Nancy J. | Scharf, Jeremiah M.
PLoS Genetics  2013;9(10):e1003864.
The direct estimation of heritability from genome-wide common variant data as implemented in the program Genome-wide Complex Trait Analysis (GCTA) has provided a means to quantify heritability attributable to all interrogated variants. We have quantified the variance in liability to disease explained by all SNPs for two phenotypically-related neurobehavioral disorders, obsessive-compulsive disorder (OCD) and Tourette Syndrome (TS), using GCTA. Our analysis yielded a heritability point estimate of 0.58 (se = 0.09, p = 5.64e-12) for TS, and 0.37 (se = 0.07, p = 1.5e-07) for OCD. In addition, we conducted multiple genomic partitioning analyses to identify genomic elements that concentrate this heritability. We examined genomic architectures of TS and OCD by chromosome, MAF bin, and functional annotations. In addition, we assessed heritability for early onset and adult onset OCD. Among other notable results, we found that SNPs with a minor allele frequency of less than 5% accounted for 21% of the TS heritability and 0% of the OCD heritability. Additionally, we identified a significant contribution to TS and OCD heritability by variants significantly associated with gene expression in two regions of the brain (parietal cortex and cerebellum) for which we had available expression quantitative trait loci (eQTLs). Finally we analyzed the genetic correlation between TS and OCD, revealing a genetic correlation of 0.41 (se = 0.15, p = 0.002). These results are very close to previous heritability estimates for TS and OCD based on twin and family studies, suggesting that very little, if any, heritability is truly missing (i.e., unassayed) from TS and OCD GWAS studies of common variation. The results also indicate that there is some genetic overlap between these two phenotypically-related neuropsychiatric disorders, but suggest that the two disorders have distinct genetic architectures.
Author Summary
Family and twin studies have shown that genetic risk factors are important in the development of Tourette Syndrome (TS) and obsessive compulsive disorder (OCD). However, efforts to identify the individual genetic risk factors involved in these two neuropsychiatric disorders have been largely unsuccessful. One possible explanation for this is that many genetic variations scattered throughout the genome each contribute a small amount to the overall risk. For TS and OCD, the genetic architecture (characterized by the number, frequency, and distribution of genetic risk factors) is presently unknown. This study examined the genetic architecture of TS and OCD in a variety of ways. We found that rare genetic changes account for more genetic risk in TS than in OCD; certain chromosomes contribute to OCD risk more than others; and variants that influence the level of genes expressed in two regions of the brain can account for a significant amount of risk for both TS and OCD. Results from this study might help in determining where, and what kind of variants are individual risk factors for TS and OCD and where they might be located in the human genome.
doi:10.1371/journal.pgen.1003864
PMCID: PMC3812053  PMID: 24204291
14.  Dissecting the genetic make-up of North-East Sardinia using a large set of haploid and autosomal markers 
Sardinia has been used for genetic studies because of its historical isolation, genetic homogeneity and increased prevalence of certain rare diseases. Controversy remains concerning the genetic substructure and the extent of genetic homogeneity, which has implications for the design of genome-wide association studies (GWAS). We revisited this issue by examining the genetic make-up of a sample from North-East Sardinia using a dense set of autosomal, Y chromosome and mitochondrial markers to assess the potential of the sample for GWAS and fine mapping studies. We genotyped individuals for 500K single-nucleotide polymorphisms, Y chromosome markers and sequenced the mitochondrial hypervariable (HVI–HVII) regions. We identified major haplogroups and compared these with other populations. We estimated linkage disequilibrium (LD) and haplotype diversity across autosomal markers, and compared these with other populations. Our results show that within Sardinia there is no major population substructure and thus it can be considered a genetically homogenous population. We did not find substantial differences in the extent of LD in Sardinians compared with other populations. However, we showed that at least 9% of genomic regions in Sardinians differed in LD structure, which is helpful for identifying functional variants using fine mapping. We concluded that Sardinia is a powerful setting for genetic studies including GWAS and other mapping approaches.
doi:10.1038/ejhg.2012.22
PMCID: PMC3421114  PMID: 22378280
Sardinia; POPRES; HAPMAP; population genetics
15.  Fine-Mapping, Gene Expression and Splicing Analysis of the Disease Associated LRRK2 Locus 
PLoS ONE  2013;8(8):e70724.
Association studies have identified several signals at the LRRK2 locus for Parkinson's disease (PD), Crohn's disease (CD) and leprosy. However, little is known about the molecular mechanisms mediating these effects. To further characterize this locus, we fine-mapped the risk association in 5,802 PD and 5,556 controls using a dense genotyping array (ImmunoChip). Using samples from 134 post-mortem control adult human brains (UK Human Brain Expression Consortium), where up to ten brain regions were available per individual, we studied the regional variation, splicing and regulation of LRRK2. We found convincing evidence for a common variant PD association located outside of the LRRK2 protein coding region (rs117762348, A>G, P = 2.56×10−8, case/control MAF 0.083/0.074, odds ratio 0.86 for the minor allele with 95% confidence interval [0.80–0.91]). We show that mRNA expression levels are highest in cortical regions and lowest in cerebellum. We find an exon quantitative trait locus (QTL) in brain samples that localizes to exons 32–33 and investigate the molecular basis of this eQTL using RNA-Seq data in n = 8 brain samples. The genotype underlying this eQTL is in strong linkage disequilibrium with the CD associated non-synonymous SNP rs3761863 (M2397T). We found two additional QTLs in liver and monocyte samples but none of these explained the common variant PD association at rs117762348. Our results characterize the LRRK2 locus, and highlight the importance and difficulties of fine-mapping and integration of multiple datasets to delineate pathogenic variants and thus develop an understanding of disease mechanisms.
doi:10.1371/journal.pone.0070724
PMCID: PMC3742662  PMID: 23967090
16.  FADS2 Genetic Variance in Combination with Fatty Acid Intake Might Alter Composition of the Fatty Acids in Brain 
PLoS ONE  2013;8(6):e68000.
Multiple lines of evidence suggest that fatty acids (FA) play an important role in cognitive function. However, little is known about the functional genetic pathways involved in cognition. The main goals of this study were to replicate previously reported interaction effects between breast feeding (BF) and FA desaturase (FADS) genetic variation on IQ and to investigate the possible mechanisms by which these variants might moderate BF effect, focusing on brain expression. Using a sample of 534 twins, we observed a trend in the moderation of BF effects on IQ by FADS2 variation. In addition, we made use of publicly available gene expression databases from both humans (193) and mice (93) and showed that FADS2 variants also correlate with FADS1 brain expression (P-value<1.1E-03). Our results provide novel clues for the understanding of the genetic mechanisms regulating FA brain expression and improve the current knowledge of the FADS moderation effect on cognition.
doi:10.1371/journal.pone.0068000
PMCID: PMC3694926  PMID: 23826354
17.  Frequency of the C9ORF72 hexanucleotide repeat expansion in ALS and FTD in diverse populations: a cross-sectional study 
Lancet Neurology  2012;11(4):323-330.
Background
A hexanucleotide repeat expansion in the C9ORF72 gene has recently been shown to cause a large proportion of amyotrophic lateral sclerosis (ALS) and fronto-temporal dementia (FTD).
Methods
We screened 4,448 patients diagnosed with ALS and 1,425 patients diagnosed with FTD drawn from diverse populations for the hexanucleotide expansion using a repeat-primed PCR assay. ALS and FTD were diagnosed according to the El Escorial and Lund-Manchester criteria respectively. Familial status was based on self-reported family history of similar neurodegenerative diseases at the time of sample collection. Haplotype data of 262 patients carrying the expansion were compared with the known Finnish founder risk haplotype across the chromosomal locus. Age-related penetrance was calculated by the Kaplan-Meier method using data from 603 individuals carrying the expansion.
Findings
The mutation was observed among 7·0% (n = 236 of 3,377) of Caucasians, 4·1% (n = 2 of 49) of African-Americans, and 8·3% (n = 6 of 72) of Hispanic individuals diagnosed with sporadic ALS, whereas the rate was 6·0% (n = 59 of 981) among Caucasians diagnosed with sporadic FTD. Among Asians, 5·0% (n = 1 of 20) of familial ALS and 66·6% (n = 2 of 3) of familial FTD cases carried the repeat expansion. In contrast, mutations were not observed among patients of Native American (n = 3 sporadic ALS), Indian (n = 31 sporadic ALS, n = 31 sporadic FTD), and Pacific Islander (n = 90 sporadic ALS) ethnicity. All patients with the repeat expansion carried, either partially or fully, the founder haplotype suggesting that the expansion occurred on a single occasion in the past (~1,500 years ago). The pathogenic expansion was non-penetrant below 35 years of age, increasing to 50·0% penetrance by 58 years of age, and was almost fully penetrant by 80 years of age.
Interpretation
We confirm that a common single Mendelian genetic lesion is implicated in a large proportion of sporadic and familial ALS and FTD. Testing for this pathogenic expansion will be important in the management and genetic counseling of patients with these fatal neurodegenerative diseases.
Funding
See Acknowledgements.
doi:10.1016/S1474-4422(12)70043-1
PMCID: PMC3322422  PMID: 22406228
18.  The chromosome 9 ALS and FTD locus is probably derived from a single founder 
Neurobiology of Aging  2011;33(1):209.e3-209.e8.
We and others have recently reported an association between ALS and single nucleotide polymorphisms on chromosome 9p21 in several populations. Here we show that the associated haplotype is the same in all populations and that several families previously shown to have genetic linkage to this region also share this haplotype. The most parsimonious explanation of these data is that there is a single founder for this form of disease.
doi:10.1016/j.neurobiolaging.2011.08.005
PMCID: PMC3312749  PMID: 21925771
Genetics; amyotrophic lateral sclerosis; frontotemporal dementia; Finland
19.  A hexanucleotide repeat expansion in C9ORF72 is the cause of chromosome 9p21-linked ALS-FTD 
Renton, Alan E. | Majounie, Elisa | Waite, Adrian | Simón-Sánchez, Javier | Rollinson, Sara | Gibbs, J. Raphael | Schymick, Jennifer C. | Laaksovirta, Hannu | van Swieten, John C. | Myllykangas, Liisa | Kalimo, Hannu | Paetau, Anders | Abramzon, Yevgeniya | Remes, Anne M. | Kaganovich, Alice | Scholz, Sonja W. | Duckworth, Jamie | Ding, Jinhui | Harmer, Daniel W. | Hernandez, Dena G. | Johnson, Janel O. | Mok, Kin | Ryten, Mina | Trabzuni, Danyah | Guerreiro, Rita J. | Orrell, Richard W. | Neal, James | Murray, Alex | Pearson, Justin | Jansen, Iris E. | Sondervan, David | Seelaar, Harro | Blake, Derek | Young, Kate | Halliwell, Nicola | Callister, Janis | Toulson, Greg | Richardson, Anna | Gerhard, Alex | Snowden, Julie | Mann, David | Neary, David | Nalls, Michael A. | Peuralinna, Terhi | Jansson, Lilja | Isoviita, Veli-Matti | Kaivorinne, Anna-Lotta | Hölttä-Vuori, Maarit | Ikonen, Elina | Sulkava, Raimo | Benatar, Michael | Wuu, Joanne | Chiò, Adriano | Restagno, Gabriella | Borghero, Giuseppe | Sabatelli, Mario | Heckerman, David | Rogaeva, Ekaterina | Zinman, Lorne | Rothstein, Jeffrey | Sendtner, Michael | Drepper, Carsten | Eichler, Evan E. | Alkan, Can | Abdullaev, Zied | Pack, Svetlana D. | Dutra, Amalia | Pak, Evgenia | Hardy, John | Singleton, Andrew | Williams, Nigel M. | Heutink, Peter | Pickering-Brown, Stuart | Morris, Huw R. | Tienari, Pentti J. | Traynor, Bryan J.
Neuron  2011;72(2):257-268.
The chromosome 9p21 amyotrophic lateral sclerosis-frontotemporal dementia (ALS-FTD) locus contains one of the last major unidentified autosomal dominant genes underlying these common neurodegenerative diseases. We have previously shown that a founder haplotype, covering the MOBKL2b, IFNK and C9ORF72 genes, is present in the majority of cases linked to this region. Here we show that there is a large hexanucleotide (GGGGCC) repeat expansion in the first intron of C9ORF72 on the affected haplotype. This repeat expansion segregates perfectly with disease in the Finnish population, underlying 46.0% of familial ALS and 21.1% of sporadic ALS in that population. Taken together with the D90A SOD1 mutation, 87% of familial ALS in Finland is now explained by a simple monogenic cause. The repeat expansion is also present in one third of familial ALS cases of outbred European descent making it the most common genetic cause of these fatal neurodegenerative diseases identified to date.
doi:10.1016/j.neuron.2011.09.010
PMCID: PMC3200438  PMID: 21944779
20.  Genome-wide association study confirms extant PD risk loci among the Dutch 
In view of the population-specific heterogeneity in reported genetic risk factors for Parkinson's disease (PD), we conducted a genome-wide association study (GWAS) in a large sample of PD cases and controls from the Netherlands. After quality control (QC), a total of 514 799 SNPs genotyped in 772 PD cases and 2024 controls were included in our analyses. Direct replication of SNPs within SNCA and BST1 confirmed these two genes to be associated with PD in the Netherlands (SNCA, rs2736990: P=1.63 × 10−5, OR=1.325 and BST1, rs12502586: P=1.63 × 10−3, OR=1.337). Within SNCA, two independent signals in two different linkage disequilibrium (LD) blocks in the 3′ and 5′ ends of the gene were detected. Besides, post-hoc analysis confirmed GAK/DGKQ, HLA and MAPT as PD risk loci among the Dutch (GAK/DGKQ, rs2242235: P=1.22 × 10−4, OR=1.51; HLA, rs4248166: P=4.39 × 10−5, OR=1.36; and MAPT, rs3785880: P=1.9 × 10−3, OR=1.19).
doi:10.1038/ejhg.2010.254
PMCID: PMC3110043  PMID: 21248740
SNCA; BST1; GAK/DGKQ; HLA; MAPT; PD
21.  Somatic retrotransposition alters the genetic landscape of the human brain 
Nature  2011;479(7374):534-537.
Retrotransposons are mobile genetic elements that employ a germ line “copy-and-paste” mechanism to spread throughout metazoan genomes1. At least 50% of the human genome is derived from retrotransposons, with three active families (L1, Alu and SVA) associated with insertional mutagenesis and disease2-3. Epigenetic and post-transcriptional suppression block retrotransposition in somatic cells4-5, excluding early embryo development and some malignancies6-7. Recent reports of L1 expression8-9 and copy number variation10-11 (CNV) in the human brain suggest L1 mobilization may also occur during later development. However, the corresponding integration sites have not been mapped. Here we apply a high-throughput method to identify numerous L1, Alu and SVA germ line mutations, as well as 7,743 putative somatic L1 insertions in the hippocampus and caudate nucleus of three individuals. Surprisingly, we also found 13,692 and 1,350 somatic Alu and SVA insertions, respectively. Our results demonstrate that retrotransposons mobilize to protein-coding genes differentially expressed and active in the brain. Thus, somatic genome mosaicism driven by retrotransposition may reshape the genetic circuitry that underpins normal and abnormal neurobiological processes.
doi:10.1038/nature10531
PMCID: PMC3224101  PMID: 22037309
22.  A Fine-Mapping Study of 7 Top Scoring Genes from a GWAS for Major Depressive Disorder 
PLoS ONE  2012;7(5):e37384.
Major depressive disorder (MDD) is a psychiatric disorder that is characterized -amongst others- by persistent depressed mood, loss of interest and pleasure and psychomotor retardation. Environmental circumstances have proven to influence the aetiology of the disease, but MDD also has an estimated 40% heritability, probably with a polygenic background. In 2009, a genome wide association study (GWAS) was performed on the Dutch GAIN-MDD cohort. A non-synonymous coding single nucleotide polymorphism (SNP) rs2522833 in the PCLO gene became only nominally significant after post-hoc analysis with an Australian cohort which used similar ascertainment. The absence of genome-wide significance may be caused by low SNP coverage of genes. To increase SNP coverage to 100% for common variants (m.a.f.>0.1, r2>0.8), we selected seven genes from the GAIN-MDD GWAS: PCLO, GZMK, ANPEP, AFAP1L1, ST3GAL6, FGF14 and PTK2B. We genotyped 349 SNPs and obtained the lowest P-value for rs2715147 in PCLO at P = 6.8E−7. We imputed, filling in missing genotypes, after which rs2715147 and rs2715148 showed the lowest P-value at P = 1.2E−6. When we created a haplotype of these SNPs together with the non-synonymous coding SNP rs2522833, the P-value decreased to P = 9.9E−7 but was not genome wide significant. Although our study did not identify a more strongly associated variant, the results for PCLO suggest that the causal variant is in high LD with rs2715147, rs2715148 and rs2522833.
doi:10.1371/journal.pone.0037384
PMCID: PMC3359349  PMID: 22649524
23.  Genetic and Clinical Features of Progranulin-Associated Frontotemporal Lobar Degeneration 
Archives of neurology  2011;68(4):488-497.
Objective
To assess the relative frequency of unique mutations and their associated characteristics in 97 individuals with mutations in progranulin (GRN), an important cause of frontotemporal lobar degeneration (FTLD).
Participants and Design
A 46-site International Frontotemporal Lobar Degeneration Collaboration was formed to collect cases of FTLD with TAR DNA-binding protein of 43-kDa (TDP-43)–positive inclusions (FTLD-TDP). We identified 97 individuals with FTLD-TDP with pathogenic GRN mutations (GRN+ FTLD-TDP), assessed their genetic and clinical characteristics, and compared them with 453 patients with FTLD-TDP in which GRN mutations were excluded (GRN− FTLD-TDP). No patients were known to be related. Neuropathologic characteristics were confirmed as FTLD-TDP in 79 of the 97 GRN+ FTLDTDP cases and all of the GRN− FTLD-TDP cases.
Results
Age at onset of FTLD was younger in patients with GRN+ FTLD-TDP vs GRN− FTLD-TDP (median, 58.0 vs 61.0 years; P<.001), as was age at death (median, 65.5 vs 69.0 years; P<.001). Concomitant motor neuron disease was much less common in GRN+ FTLDTDP vs GRN− FTLD-TDP (5.4% vs 26.3%; P<.001). Fifty different GRN mutations were observed, including 2 novel mutations: c.139delG (p.D47TfsX7) and c.378C>A (p.C126X). The 2 most common GRN mutations were c.1477C>T (p.R493X, found in 18 patients, representing 18.6% of GRN cases) and c.26C>A (p.A9D, found in 6 patients, representing 6.2% of cases). Patients with the c.1477C>T mutation shared a haplotype on chromosome 17; clinically, they resembled patients with other GRN mutations. Patients with the c.26C>A mutation appeared to have a younger age at onset of FTLD and at death and more parkinsonian features than those with other GRN mutations.
Conclusion
GRN+ FTLD-TDP differs in key features from GRN− FTLD-TDP.
doi:10.1001/archneurol.2011.53
PMCID: PMC3160280  PMID: 21482928
24.  Frequency of the C9orf72 hexanucleotide repeat expansion in patients with amyotrophic lateral sclerosis and frontotemporal dementia: a cross-sectional study 
Lancet Neurology  2012;11(4):323-330.
Summary
Background
We aimed to accurately estimate the frequency of a hexanucleotide repeat expansion in C9orf72 that has been associated with a large proportion of cases of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD).
Methods
We screened 4448 patients diagnosed with ALS (El Escorial criteria) and 1425 patients with FTD (Lund-Manchester criteria) from 17 regions worldwide for the GGGGCC hexanucleotide expansion using a repeat-primed PCR assay. We assessed familial disease status on the basis of self-reported family history of similar neurodegenerative diseases at the time of sample collection. We compared haplotype data for 262 patients carrying the expansion with the known Finnish founder risk haplotype across the chromosomal locus. We calculated age-related penetrance using the Kaplan-Meier method with data for 603 individuals with the expansion.
Findings
In patients with sporadic ALS, we identified the repeat expansion in 236 (7·0%) of 3377 white individuals from the USA, Europe, and Australia, two (4·1%) of 49 black individuals from the USA, and six (8·3%) of 72 Hispanic individuals from the USA. The mutation was present in 217 (39·3%) of 552 white individuals with familial ALS from Europe and the USA. 59 (6·0%) of 981 white Europeans with sporadic FTD had the mutation, as did 99 (24·8%) of 400 white Europeans with familial FTD. Data for other ethnic groups were sparse, but we identified one Asian patient with familial ALS (from 20 assessed) and two with familial FTD (from three assessed) who carried the mutation. The mutation was not carried by the three Native Americans or 360 patients from Asia or the Pacific Islands with sporadic ALS who were tested, or by 41 Asian patients with sporadic FTD. All patients with the repeat expansion had (partly or fully) the founder haplotype, suggesting a one-off expansion occurring about 1500 years ago. The pathogenic expansion was non-penetrant in individuals younger than 35 years, 50% penetrant by 58 years, and almost fully penetrant by 80 years.
Interpretation
A common Mendelian genetic lesion in C9orf72 is implicated in many cases of sporadic and familial ALS and FTD. Testing for this pathogenic expansion should be considered in the management and genetic counselling of patients with these fatal neurodegenerative diseases.
Funding
Full funding sources listed at end of paper (see Acknowledgments).
doi:10.1016/S1474-4422(12)70043-1
PMCID: PMC3322422  PMID: 22406228
25.  Comprehensive Research Synopsis and Systematic Meta-Analyses in Parkinson's Disease Genetics: The PDGene Database 
PLoS Genetics  2012;8(3):e1002548.
More than 800 published genetic association studies have implicated dozens of potential risk loci in Parkinson's disease (PD). To facilitate the interpretation of these findings, we have created a dedicated online resource, PDGene, that comprehensively collects and meta-analyzes all published studies in the field. A systematic literature screen of ∼27,000 articles yielded 828 eligible articles from which relevant data were extracted. In addition, individual-level data from three publicly available genome-wide association studies (GWAS) were obtained and subjected to genotype imputation and analysis. Overall, we performed meta-analyses on more than seven million polymorphisms originating either from GWAS datasets and/or from smaller scale PD association studies. Meta-analyses on 147 SNPs were supplemented by unpublished GWAS data from up to 16,452 PD cases and 48,810 controls. Eleven loci showed genome-wide significant (P<5×10−8) association with disease risk: BST1, CCDC62/HIP1R, DGKQ/GAK, GBA, LRRK2, MAPT, MCCC1/LAMP3, PARK16, SNCA, STK39, and SYT11/RAB25. In addition, we identified novel evidence for genome-wide significant association with a polymorphism in ITGA8 (rs7077361, OR 0.88, P = 1.3×10−8). All meta-analysis results are freely available on a dedicated online database (www.pdgene.org), which is cross-linked with a customized track on the UCSC Genome Browser. Our study provides an exhaustive and up-to-date summary of the status of PD genetics research that can be readily scaled to include the results of future large-scale genetics projects, including next-generation sequencing studies.
Author Summary
The genetic basis of Parkinson's disease is complex, i.e. it is determined by a number of different disease-causing and disease-predisposing genes. Especially the latter have proven difficult to find, evidenced by more than 800 published genetic association studies, typically showing discrepant results. To facilitate the interpretation of this large and continuously increasing body of data, we have created a freely available online database (“PDGene”: http://www.pdgene.org) which provides an exhaustive account of all published genetic association studies in PD. One particularly useful feature is the calculation and display of up-to-date summary statistics of published data for overlapping DNA sequence variants (polymorphisms). These meta-analyses revealed eleven gene loci that showed a statistically very significant (P<5×10−8; a.k.a. genome-wide significance) association with risk for PD: BST1, CCDC62/HIP1R, DGKQ/GAK, GBA, LRRK2, MAPT, MCCC1/LAMP3, PARK16, SNCA, STK39, SYT11/RAB25. In addition and purely by data-mining, we identified one novel PD susceptibility locus in a gene called ITGA8 (rs7077361, P = 1.3×10−8). We note that our continuously updated database represents the most comprehensive research synopsis of genetic association studies in PD to date. In addition to vastly facilitating the work of other PD geneticists, our approach may serve as a valuable example for other complex diseases.
doi:10.1371/journal.pgen.1002548
PMCID: PMC3305333  PMID: 22438815

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