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1.  Febrile temperatures unmask biophysical defects in Nav1.1 epilepsy mutations supportive of seizure initiation 
The Journal of General Physiology  2013;142(6):641-653.
Generalized epilepsy with febrile seizures plus (GEFS+) is an early onset febrile epileptic syndrome with therapeutic responsive (a)febrile seizures continuing later in life. Dravet syndrome (DS) or severe myoclonic epilepsy of infancy has a complex phenotype including febrile generalized or hemiclonic convulsions before the age of 1, followed by intractable myoclonic, complex partial, or absence seizures. Both diseases can result from mutations in the Nav1.1 sodium channel, and initially, seizures are typically triggered by fever. We previously characterized two Nav1.1 mutants—R859H (GEFS+) and R865G (DS)—at room temperature and reported a mixture of biophysical gating defects that could not easily predict the phenotype presentation as either GEFS+ or DS. In this study, we extend the characterization of Nav1.1 wild-type, R859H, and R865G channels to physiological (37°C) and febrile (40°C) temperatures. At physiological temperature, a variety of biophysical defects were detected in both mutants, including a hyperpolarized shift in the voltage dependence of activation and a delayed recovery from fast and slow inactivation. Interestingly, at 40°C we also detected additional gating defects for both R859H and R865G mutants. The GEFS+ mutant R859H showed a loss of function in the voltage dependence of inactivation and an increased channel use-dependency at 40°C with no reduction in peak current density. The DS mutant R865G exhibited reduced peak sodium currents, enhanced entry into slow inactivation, and increased use-dependency at 40°C. Our results suggest that fever-induced temperatures exacerbate the gating defects of R859H or R865G mutants and may predispose mutation carriers to febrile seizures.
doi:10.1085/jgp.201311042
PMCID: PMC3840920  PMID: 24277604
2.  Polymorphisms in ACVRL1 and Endoglin genes are not associated with sporadic and HHT related brain AVMs in Dutch patients 
Translational stroke research  2012;4(3):375-378.
We aimed to replicate the association of the IVS3-35A>G polymorphism in the activin receptor-like kinase (ACVRL) 1 gene and the 207G>A polymorphism in the endoglin (ENG) gene with sporadic brain arteriovenous malformations (BAVM) in Dutch BAVM patients. In addition, we assessed whether these polymorphisms contribute to the risk of BAVM in patients with hereditary haemorrhagic telangiectasia type 1 (HHT1). We genotyped 143 Dutch sporadic BAVM patients and 360 healthy volunteers for four variants in the ACVRL1 gene including IVS3-35A>G and two variants in the ENG gene including 207G>A. Differences in allele and genotype frequencies between sporadic BAVM patients and controls and their combined effect were analysed with a likelihood ratio test. Furthermore, we compared the allele and genotype frequencies between 24 HHT1 patients with a BAVM with those of a relative with HHT1 without a BAVM in a matched pair analysis using Wilcoxon signed rank test. No significant differences in allele frequency were found between sporadic BAVM cases and controls or between HHT1 patients with and without BAVM for any of the polymorphisms or the combination of ACVRL1 and ENG polymorphisms. Meta-analysis of the current and the two previous studies for the ACVRL1 IVS3-35A polymorphism showed a persisting association between the ACVRL1 IVS3-35A polymorphism and risk of sporadic BAVM (OR 1.86; 95% CI 1.32–2.61, p<0.001). We did not replicate the previously found association between a polymorphism in ACVRL1 IVS3-35A>G and BAVM in Dutch patients. However, meta-analysis did not rule out a possible effect.
doi:10.1007/s12975-012-0231-4
PMCID: PMC4038301  PMID: 24323303
Arteriovenous malformations; Etiology; Genetics; Neurogenetics; Cerebrovascular disease
3.  A Genome-Wide Investigation of Copy Number Variation in Patients with Sporadic Brain Arteriovenous Malformation 
PLoS ONE  2013;8(10):e71434.
Background
Brain arteriovenous malformations (BAVM) are clusters of abnormal blood vessels, with shunting of blood from the arterial to venous circulation and a high risk of rupture and intracranial hemorrhage. Most BAVMs are sporadic, but also occur in patients with Hereditary Hemorrhagic Telangiectasia, a Mendelian disorder caused by mutations in genes in the transforming growth factor beta (TGFβ) signaling pathway.
Methods
To investigate whether copy number variations (CNVs) contribute to risk of sporadic BAVM, we performed a genome-wide association study in 371 sporadic BAVM cases and 563 healthy controls, all Caucasian. Cases and controls were genotyped using the Affymetrix 6.0 array. CNVs were called using the PennCNV and Birdsuite algorithms and analyzed via segment-based and gene-based approaches. Common and rare CNVs were evaluated for association with BAVM.
Results
A CNV region on 1p36.13, containing the neuroblastoma breakpoint family, member 1 gene (NBPF1), was significantly enriched with duplications in BAVM cases compared to controls (P = 2.2×10−9); NBPF1 was also significantly associated with BAVM in gene-based analysis using both PennCNV and Birdsuite. We experimentally validated the 1p36.13 duplication; however, the association did not replicate in an independent cohort of 184 sporadic BAVM cases and 182 controls (OR = 0.81, P = 0.8). Rare CNV analysis did not identify genes significantly associated with BAVM.
Conclusion
We did not identify common CNVs associated with sporadic BAVM that replicated in an independent cohort. Replication in larger cohorts is required to elucidate the possible role of common or rare CNVs in BAVM pathogenesis.
doi:10.1371/journal.pone.0071434
PMCID: PMC3789669  PMID: 24098321
4.  Epilepsy, hippocampal sclerosis and febrile seizures linked by common genetic variation around SCN1A 
Kasperavičiūtė, Dalia | Catarino, Claudia B. | Matarin, Mar | Leu, Costin | Novy, Jan | Tostevin, Anna | Leal, Bárbara | Hessel, Ellen V. S. | Hallmann, Kerstin | Hildebrand, Michael S. | Dahl, Hans-Henrik M. | Ryten, Mina | Trabzuni, Daniah | Ramasamy, Adaikalavan | Alhusaini, Saud | Doherty, Colin P. | Dorn, Thomas | Hansen, Jörg | Krämer, Günter | Steinhoff, Bernhard J. | Zumsteg, Dominik | Duncan, Susan | Kälviäinen, Reetta K. | Eriksson, Kai J. | Kantanen, Anne-Mari | Pandolfo, Massimo | Gruber-Sedlmayr, Ursula | Schlachter, Kurt | Reinthaler, Eva M. | Stogmann, Elisabeth | Zimprich, Fritz | Théâtre, Emilie | Smith, Colin | O’Brien, Terence J. | Meng Tan, K. | Petrovski, Slave | Robbiano, Angela | Paravidino, Roberta | Zara, Federico | Striano, Pasquale | Sperling, Michael R. | Buono, Russell J. | Hakonarson, Hakon | Chaves, João | Costa, Paulo P. | Silva, Berta M. | da Silva, António M. | de Graan, Pierre N. E. | Koeleman, Bobby P. C. | Becker, Albert | Schoch, Susanne | von Lehe, Marec | Reif, Philipp S. | Rosenow, Felix | Becker, Felicitas | Weber, Yvonne | Lerche, Holger | Rössler, Karl | Buchfelder, Michael | Hamer, Hajo M. | Kobow, Katja | Coras, Roland | Blumcke, Ingmar | Scheffer, Ingrid E. | Berkovic, Samuel F. | Weale, Michael E. | Delanty, Norman | Depondt, Chantal | Cavalleri, Gianpiero L. | Kunz, Wolfram S. | Sisodiya, Sanjay M.
Brain  2013;136(10):3140-3150.
Epilepsy comprises several syndromes, amongst the most common being mesial temporal lobe epilepsy with hippocampal sclerosis. Seizures in mesial temporal lobe epilepsy with hippocampal sclerosis are typically drug-resistant, and mesial temporal lobe epilepsy with hippocampal sclerosis is frequently associated with important co-morbidities, mandating the search for better understanding and treatment. The cause of mesial temporal lobe epilepsy with hippocampal sclerosis is unknown, but there is an association with childhood febrile seizures. Several rarer epilepsies featuring febrile seizures are caused by mutations in SCN1A, which encodes a brain-expressed sodium channel subunit targeted by many anti-epileptic drugs. We undertook a genome-wide association study in 1018 people with mesial temporal lobe epilepsy with hippocampal sclerosis and 7552 control subjects, with validation in an independent sample set comprising 959 people with mesial temporal lobe epilepsy with hippocampal sclerosis and 3591 control subjects. To dissect out variants related to a history of febrile seizures, we tested cases with mesial temporal lobe epilepsy with hippocampal sclerosis with (overall n = 757) and without (overall n = 803) a history of febrile seizures. Meta-analysis revealed a genome-wide significant association for mesial temporal lobe epilepsy with hippocampal sclerosis with febrile seizures at the sodium channel gene cluster on chromosome 2q24.3 [rs7587026, within an intron of the SCN1A gene, P = 3.36 × 10−9, odds ratio (A) = 1.42, 95% confidence interval: 1.26–1.59]. In a cohort of 172 individuals with febrile seizures, who did not develop epilepsy during prospective follow-up to age 13 years, and 6456 controls, no association was found for rs7587026 and febrile seizures. These findings suggest SCN1A involvement in a common epilepsy syndrome, give new direction to biological understanding of mesial temporal lobe epilepsy with hippocampal sclerosis with febrile seizures, and open avenues for investigation of prognostic factors and possible prevention of epilepsy in some children with febrile seizures.
doi:10.1093/brain/awt233
PMCID: PMC3784283  PMID: 24014518
mesial temporal lobe epilepsy; mesial temporal sclerosis; SCN1A; association; complex genetics
5.  Identification of CSK as a systemic sclerosis genetic risk factor through Genome Wide Association Study follow-up 
Human Molecular Genetics  2012;21(12):2825-2835.
Systemic sclerosis (SSc) is complex autoimmune disease affecting the connective tissue; influenced by genetic and environmental components. Recently, we performed the first successful genome-wide association study (GWAS) of SSc. Here, we perform a large replication study to better dissect the genetic component of SSc. We selected 768 polymorphisms from the previous GWAS and genotyped them in seven replication cohorts from Europe. Overall significance was calculated for replicated significant SNPs by meta-analysis of the replication cohorts and replication-GWAS cohorts (3237 cases and 6097 controls). Six SNPs in regions not previously associated with SSc were selected for validation in another five independent cohorts, up to a total of 5270 SSc patients and 8326 controls. We found evidence for replication and overall genome-wide significance for one novel SSc genetic risk locus: CSK [P-value = 5.04 × 10−12, odds ratio (OR) = 1.20]. Additionally, we found suggestive association in the loci PSD3 (P-value = 3.18 × 10−7, OR = 1.36) and NFKB1 (P-value = 1.03 × 10−6, OR = 1.14). Additionally, we strengthened the evidence for previously confirmed associations. This study significantly increases the number of known putative genetic risk factors for SSc, including the genes CSK, PSD3 and NFKB1, and further confirms six previously described ones.
doi:10.1093/hmg/dds099
PMCID: PMC3368627  PMID: 22407130
6.  Association of variation in Fcγ receptor 3B gene copy number with rheumatoid arthritis in Caucasian samples 
Annals of the rheumatic diseases  2010;69(9):1711-1716.
Objective
There is increasing evidence that variation in gene copy number (CN) influences clinical phenotype. The low-affinity Fcγ receptor 3B (FCGR3B) located in the FCGR gene cluster is a CN polymorphic gene involved in the recruitment to sites of inflammation and activation of polymorphonuclear neutrophils (PMNs). Given recent evidence that low FCGR3B CN is a risk factor for systemic but not organ-specific autoimmune disease and the potential importance of PMN in the pathophysiology of rheumatoid arthritis (RA), the authors hypothesised that FCGR3B gene dosage influences susceptibility to RA.
Methods
FCGR3B CN was measured in 643 cases of RA and 461 controls from New Zealand (NZ), with follow-up analysis in 768 cases and 702 controls from the Netherlands and 250 cases and 211 controls from the UK. All subjects were of Caucasian ancestry.
Results
Significant evidence for an association between CN <2 and RA was observed in the Dutch cohort (OR 2.01 (95% CI 1.37 to 2.94), p=3×10–4) but not in the two smaller cohorts (OR 1.45 (95% CI 0.92 to 2.26), p=0.11 and OR 1.33 (95% CI 0.58 to 3.02), p=0.50 for the NZ and UK populations, respectively). The association was evident in a meta-analysis which included a previously published Caucasian sample set (OR 1.67 (95% CI 1.28 to 2.17), p=1.2×10–4).
Conclusions
One possible mechanism to explain the association between reduced FCGR3B CN and RA is the reduced clearance of immune complex during infl ammation. However, it is not known whether the association between RA and FCGR3B CN is aetiological or acts as a proxy marker for another biologically relevant variant. More detailed examination of genetic variation within the FCGR gene cluster is required.
doi:10.1136/ard.2009.123588
PMCID: PMC3670580  PMID: 20472591
7.  Nav1.1 Dysfunction in Genetic Epilepsy with Febrile Seizures Plus or Dravet Syndrome 
The European journal of neuroscience  2011;34(8):1268-1275.
Relatively few SCN1A mutations associated with genetic epilepsy with febrile seizures plus (GEFS+) and Dravet syndrome (DS) have been functionally characterized. In contrast to GEFS+, many mutations detected in DS patients are predicted to have complete loss-of-function. However, functional consequences are not immediately apparent for DS missense mutations. Therefore, we performed biophysical analysis of three SCN1A missense mutations (R865G, R946C, and R946H) we detected in six patients with DS. Furthermore, we compared the functionality of the R865G DS mutation with that of a R859H mutation detected in a GEFS+ patient; both mutations reside in the same voltage sensor domain of Nav1.1. The four mutations were co-expressed with β1 and β2-subunits in tsA201 cells and characterized using the whole-cell patch clamp technique.
The two DS mutations, R946C and R946H, were non-functional. However, the novel voltage sensor mutants R859H (GEFS+) and R865G (DS) produced sodium current densities comparable to wild-type channels. Both mutants had negative shifts in the voltage dependence of activation, slower recovery from inactivation, and increased persistent current. Only the GEFS+ mutant exhibited a loss-of-function in voltage dependent channel availability.
Our results suggest that the R859H mutation causes GEFS+ by a mixture of biophysical defects in Nav1.1 gating. Interestingly, while loss of Nav1.1 function is common in DS, the R865G mutation may cause DS by overall gain-of-function defects.
doi:10.1111/j.1460-9568.2011.07826.x
PMCID: PMC3195841  PMID: 21864321
GEFS+; Dravet syndrome; epilepsy; SCN1A; human
8.  Genes in the Ureteric Budding Pathway: Association Study on Vesico-Ureteral Reflux Patients 
PLoS ONE  2012;7(4):e31327.
Vesico-ureteral reflux (VUR) is the retrograde passage of urine from the bladder to the urinary tract and causes 8.5% of end-stage renal disease in children. It is a complex genetic developmental disorder, in which ectopic embryonal ureteric budding is implicated in the pathogenesis. VUR is part of the spectrum of Congenital Anomalies of the Kidney and Urinary Tract (CAKUT). We performed an extensive association study for primary VUR using a two-stage, case-control design, investigating 44 candidate genes in the ureteric budding pathway in 409 Dutch VUR patients. The 44 genes were selected from the literature and a set of 567 single nucleotide polymorphisms (SNPs) capturing their genetic variation was genotyped in 207 cases and 554 controls. The 14 SNPs with p<0.005 were included in a follow-up study in 202 cases and 892 controls. Of the total cohort, ∼50% showed a clear-cut primary VUR phenotype and ∼25% had both a duplex collecting system and VUR. We also looked for association in these two extreme phenotype groups. None of the SNPs reached a significant p-value. Common genetic variants in four genes (GREM1, EYA1, ROBO2 and UPK3A) show a trend towards association with the development of primary VUR (GREM1, EYA1, ROBO2) or duplex collecting system (EYA1 and UPK3A). SNPs in three genes (TGFB1, GNB3 and VEGFA) have been shown to be associated with VUR in other populations. Only the result of rs1800469 in TGFB1 hinted at association in our study. This is the first extensive study of common variants in the genes of the ureteric budding pathway and the genetic susceptibility to primary VUR.
doi:10.1371/journal.pone.0031327
PMCID: PMC3338743  PMID: 22558067
9.  Multicenter cohort association study of SLC2A1 single nucleotide polymorphisms and age-related macular degeneration 
Molecular Vision  2012;18:657-674.
Purpose
Age-related macular degeneration (AMD) is a major cause of blindness in older adults and has a genetically complex background. This study examines the potential association between single nucleotide polymorphisms (SNPs) in the glucose transporter 1 (SLC2A1) gene and AMD. SLC2A1 regulates the bioavailability of glucose in the retinal pigment epithelium (RPE), which might influence oxidative stress–mediated AMD pathology.
Methods
Twenty-two SNPs spanning the SLC2A1 gene were genotyped in 375 cases and 199 controls from an initial discovery cohort (the Amsterdam-Rotterdam-Netherlands study). Replication testing was performed in The Rotterdam Study (the Netherlands) and study populations from Würzburg (Germany), the Age Related Eye Disease Study (AREDS; United States), Columbia University (United States), and Iowa University (United States). Subsequently, a meta-analysis of SNP association was performed.
Results
In the discovery cohort, significant genotypic association between three SNPs (rs3754219, rs4660687, and rs841853) and AMD was found. Replication in five large independent (Caucasian) cohorts (4,860 cases and 4,004 controls) did not yield consistent association results. The genotype frequencies for these SNPs were significantly different for the controls and/or cases among the six individual populations. Meta-analysis revealed significant heterogeneity of effect between the studies.
Conclusions
No overall association between SLC2A1 SNPs and AMD was demonstrated. Since the genotype frequencies for the three SLC2A1 SNPs were significantly different for the controls and/or cases between the six cohorts, this study corroborates previous evidence that population dependent genetic risk heterogeneity in AMD exists.
PMCID: PMC3324365  PMID: 22509097
10.  Correction: Identification of Novel Genetic Markers Associated with Clinical Phenotypes of Systemic Sclerosis through a Genome-Wide Association Strategy 
Gorlova, Olga | Martin, Jose-Ezequiel | Rueda, Blanca | Koeleman, Bobby P. C. | Ying, Jun | Teruel, Maria | Diaz-Gallo, Lina-Marcela | Broen, Jasper C. | Vonk, Madelon C. | Simeon, Carmen P. | Alizadeh, Behrooz Z. | Coenen, Marieke J. H. | Voskuyl, Alexandre E. | Schuerwegh, Annemie J. | van Riel, Piet L. C. M. | Vanthuyne, Marie | van 't Slot, Ruben | Italiaander, Annet | Ophoff, Roel A. | Hunzelmann, Nicolas | Fonollosa, Vicente | Ortego-Centeno, Norberto | González-Gay, Miguel A. | García-Hernández, Francisco J. | González-Escribano, María F. | Airo, Paolo | van Laar, Jacob | Worthington, Jane | Hesselstrand, Roger | Smith, Vanessa | de Keyser, Filip | Houssiau, Fredric | Chee, Meng May | Madhok, Rajan | Shiels, Paul G. | Westhovens, Rene | Kreuter, Alexander | de Baere, Elfride | Witte, Torsten | Padyukov, Leonid | Nordin, Annika | Scorza, Raffaella | Lunardi, Claudio | Lie, Benedicte A. | Hoffmann-Vold, Anna-Maria | Palm, Øyvind | García de la Peña, Paloma | Carreira, Patricia | Varga, John | Hinchcliff, Monique | Lee, Annette T. | Gourh, Pravitt | Amos, Christopher I. | Wigley, Frederick M. | Hummers, Laura K. | Nelson, J. Lee | Riemekasten, Gabriella | Herrick, Ariane | Beretta, Lorenzo | Fonseca, Carmen | Denton, Christopher P. | Gregersen, Peter K. | Agarwal, Sandeep | Assassi, Shervin | Tan, Filemon K. | Arnett, Frank C. | Radstake, Timothy R. D. J. | Mayes, Maureen D. | Martin, Javier
PLoS Genetics  2011;7(8):10.1371/annotation/3aeebb2e-64e5-4548-8d65-1f2d5dfeb073.
doi:10.1371/annotation/3aeebb2e-64e5-4548-8d65-1f2d5dfeb073
PMCID: PMC3166261
11.  Correction: Identification of Novel Genetic Markers Associated with Clinical Phenotypes of Systemic Sclerosis through a Genome-Wide Association Strategy 
Gorlova, Olga | Martin, Jose-Ezequiel | Rueda, Blanca | Koeleman, Bobby P. C. | Ying, Jun | Teruel, Maria | Diaz-Gallo, Lina-Marcela | Broen, Jasper C. | Vonk, Madelon C. | Simeon, Carmen P. | Alizadeh, Behrooz Z. | Coenen, Marieke J. H. | Voskuyl, Alexandre E. | Schuerwegh, Annemie J. | van Riel, Piet L. C. M. | Vanthuyne, Marie | van 't Slot, Ruben | Italiaander, Annet | Ophoff, Roel A. | Hunzelmann, Nicolas | Fonollosa, Vicente | Ortego-Centeno, Norberto | González-Gay, Miguel A. | García-Hernández, Francisco J. | González-Escribano, María F. | Airo, Paolo | van Laar, Jacob | Worthington, Jane | Hesselstrand, Roger | Smith, Vanessa | de Keyser, Filip | Houssiau, Fredric | Chee, Meng May | Madhok, Rajan | Shiels, Paul G. | Westhovens, Rene | Kreuter, Alexander | de Baere, Elfride | Witte, Torsten | Padyukov, Leonid | Nordin, Annika | Scorza, Raffaella | Lunardi, Claudio | Lie, Benedicte A. | Hoffmann-Vold, Anna-Maria | Palm, Øyvind | García de la Peña, Paloma | Carreira, Patricia | Varga, John | Hinchcliff, Monique | Lee, Annette T. | Gourh, Pravitt | Amos, Christopher I. | Wigley, Frederick M. | Hummers, Laura K. | Nelson, J. Lee | Riemekasten, Gabriella | Herrick, Ariane | Beretta, Lorenzo | Fonseca, Carmen | Denton, Christopher P. | Gregersen, Peter K. | Agarwal, Sandeep | Assassi, Shervin | Tan, Filemon K. | Arnett, Frank C. | Radstake, Timothy R. D. J. | Mayes, Maureen D. | Martin, Javier
PLoS Genetics  2011;7(8):10.1371/annotation/7a52649c-0942-4bd8-a5d3-3cdacca03cd8.
doi:10.1371/annotation/7a52649c-0942-4bd8-a5d3-3cdacca03cd8
PMCID: PMC3166262
12.  Identification of Novel Genetic Markers Associated with Clinical Phenotypes of Systemic Sclerosis through a Genome-Wide Association Strategy 
Gorlova, Olga | Martin, Jose-Ezequiel | Rueda, Blanca | Koeleman, Bobby P. C. | Ying, Jun | Teruel, Maria | Diaz-Gallo, Lina-Marcela | Broen, Jasper C. | Vonk, Madelon C. | Simeon, Carmen P. | Alizadeh, Behrooz Z. | Coenen, Marieke J. H. | Voskuyl, Alexandre E. | Schuerwegh, Annemie J. | van Riel, Piet L. C. M. | Vanthuyne, Marie | van 't Slot, Ruben | Italiaander, Annet | Ophoff, Roel A. | Hunzelmann, Nicolas | Fonollosa, Vicente | Ortego-Centeno, Norberto | González-Gay, Miguel A. | García-Hernández, Francisco J. | González-Escribano, María F. | Airo, Paolo | van Laar, Jacob | Worthington, Jane | Hesselstrand, Roger | Smith, Vanessa | de Keyser, Filip | Houssiau, Fredric | Chee, Meng May | Madhok, Rajan | Shiels, Paul G. | Westhovens, Rene | Kreuter, Alexander | de Baere, Elfride | Witte, Torsten | Padyukov, Leonid | Nordin, Annika | Scorza, Raffaella | Lunardi, Claudio | Lie, Benedicte A. | Hoffmann-Vold, Anna-Maria | Palm, Øyvind | García de la Peña, Paloma | Carreira, Patricia | Varga, John | Hinchcliff, Monique | Lee, Annette T. | Gourh, Pravitt | Amos, Christopher I. | Wigley, Frederick M. | Hummers, Laura K. | Hummers, J. | Nelson, J. Lee | Riemekasten, Gabriella | Herrick, Ariane | Beretta, Lorenzo | Fonseca, Carmen | Denton, Christopher P. | Gregersen, Peter K. | Agarwal, Sandeep | Assassi, Shervin | Tan, Filemon K. | Arnett, Frank C. | Radstake, Timothy R. D. J. | Mayes, Maureen D. | Martin, Javier
PLoS Genetics  2011;7(7):e1002178.
The aim of this study was to determine, through a genome-wide association study (GWAS), the genetic components contributing to different clinical sub-phenotypes of systemic sclerosis (SSc). We considered limited (lcSSc) and diffuse (dcSSc) cutaneous involvement, and the relationships with presence of the SSc-specific auto-antibodies, anti-centromere (ACA), and anti-topoisomerase I (ATA). Four GWAS cohorts, comprising 2,296 SSc patients and 5,171 healthy controls, were meta-analyzed looking for associations in the selected subgroups. Eighteen polymorphisms were further tested in nine independent cohorts comprising an additional 3,175 SSc patients and 4,971 controls. Conditional analysis for associated SNPs in the HLA region was performed to explore their independent association in antibody subgroups. Overall analysis showed that non-HLA polymorphism rs11642873 in IRF8 gene to be associated at GWAS level with lcSSc (P = 2.32×10−12, OR = 0.75). Also, rs12540874 in GRB10 gene (P = 1.27 × 10−6, OR = 1.15) and rs11047102 in SOX5 gene (P = 1.39×10−7, OR = 1.36) showed a suggestive association with lcSSc and ACA subgroups respectively. In the HLA region, we observed highly associated allelic combinations in the HLA-DQB1 locus with ACA (P = 1.79×10−61, OR = 2.48), in the HLA-DPA1/B1 loci with ATA (P = 4.57×10−76, OR = 8.84), and in NOTCH4 with ACA P = 8.84×10−21, OR = 0.55) and ATA (P = 1.14×10−8, OR = 0.54). We have identified three new non-HLA genes (IRF8, GRB10, and SOX5) associated with SSc clinical and auto-antibody subgroups. Within the HLA region, HLA-DQB1, HLA-DPA1/B1, and NOTCH4 associations with SSc are likely confined to specific auto-antibodies. These data emphasize the differential genetic components of subphenotypes of SSc.
Author Summary
Scleroderma or systemic sclerosis is a complex autoimmune disease affecting one individual of every 100,000 in Caucasian populations. Even though current genetic studies have led to better understanding of the pathogenesis of the disease, much remains unknown. Scleroderma is a heterogeneous disease, which can be subdivided according to different criteria, such as the involvement of organs and the presence of specific autoantibodies. Such subgroups present more homogeneous genetic groups, and some genetic associations with these manifestations have already been described. Through reanalysis of a genome-wide association study data, we identify three novel genes containing genetic variations which predispose to subphenotypes of the disease (IRF8, GRB10, and SOX5). Also, we better characterize the patterns of associated loci found in the HLA region. Together, our findings lead to a better understanding of the genetic component of scleroderma.
doi:10.1371/journal.pgen.1002178
PMCID: PMC3136437  PMID: 21779181
13.  15q13.3 microdeletions increase risk of idiopathic generalized epilepsy 
Nature genetics  2009;41(2):160-162.
We identified 15q13.3 microdeletions encompassing the CHRNA7 gene in 12 of 1,223 individuals with idiopathic generalized epilepsy (IGE), which were not detected in 3,699 controls (joint P = 5.32 × 10−8). Most deletion carriers showed common IGE syndromes without other features previously associated with 15q13.3 microdeletions, such as intellectual disability, autism or schizophrenia. Our results indicate that 15q13.3 microdeletions constitute the most prevalent risk factor for common epilepsies identified to date.
doi:10.1038/ng.292
PMCID: PMC3026630  PMID: 19136953
14.  Recurrent microdeletions at 15q11.2 and 16p13.11 predispose to idiopathic generalized epilepsies 
Brain  2009;133(1):23-32.
Idiopathic generalized epilepsies account for 30% of all epilepsies. Despite a predominant genetic aetiology, the genetic factors predisposing to idiopathic generalized epilepsies remain elusive. Studies of structural genomic variations have revealed a significant excess of recurrent microdeletions at 1q21.1, 15q11.2, 15q13.3, 16p11.2, 16p13.11 and 22q11.2 in various neuropsychiatric disorders including autism, intellectual disability and schizophrenia. Microdeletions at 15q13.3 have recently been shown to constitute a strong genetic risk factor for common idiopathic generalized epilepsy syndromes, implicating that other recurrent microdeletions may also be involved in epileptogenesis. This study aimed to investigate the impact of five microdeletions at the genomic hotspot regions 1q21.1, 15q11.2, 16p11.2, 16p13.11 and 22q11.2 on the genetic risk to common idiopathic generalized epilepsy syndromes. The candidate microdeletions were assessed by high-density single nucleotide polymorphism arrays in 1234 patients with idiopathic generalized epilepsy from North-western Europe and 3022 controls from the German population. Microdeletions were validated by quantitative polymerase chain reaction and their breakpoints refined by array comparative genomic hybridization. In total, 22 patients with idiopathic generalized epilepsy (1.8%) carried one of the five novel microdeletions compared with nine controls (0.3%) (odds ratio = 6.1; 95% confidence interval 2.8–13.2; χ2 = 26.7; 1 degree of freedom; P = 2.4 × 10−7). Microdeletions were observed at 1q21.1 [Idiopathic generalized epilepsy (IGE)/control: 1/1], 15q11.2 (IGE/control: 12/6), 16p11.2 IGE/control: 1/0, 16p13.11 (IGE/control: 6/2) and 22q11.2 (IGE/control: 2/0). Significant associations with IGEs were found for the microdeletions at 15q11.2 (odds ratio = 4.9; 95% confidence interval 1.8–13.2; P = 4.2 × 10−4) and 16p13.11 (odds ratio = 7.4; 95% confidence interval 1.3–74.7; P = 0.009). Including nine patients with idiopathic generalized epilepsy in this cohort with known 15q13.3 microdeletions (IGE/control: 9/0), parental transmission could be examined in 14 families. While 10 microdeletions were inherited (seven maternal and three paternal transmissions), four microdeletions occurred de novo at 15q13.3 (n = 1), 16p13.11 (n = 2) and 22q11.2 (n = 1). Eight of the transmitting parents were clinically unaffected, suggesting that the microdeletion itself is not sufficient to cause the epilepsy phenotype. Although the microdeletions investigated are individually rare (<1%) in patients with idiopathic generalized epilepsy, they collectively seem to account for a significant fraction of the genetic variance in common idiopathic generalized epilepsy syndromes. The present results indicate an involvement of microdeletions at 15q11.2 and 16p13.11 in epileptogenesis and strengthen the evidence that recurrent microdeletions at 15q11.2, 15q13.3 and 16p13.11 confer a pleiotropic susceptibility effect to a broad range of neuropsychiatric disorders.
doi:10.1093/brain/awp262
PMCID: PMC2801323  PMID: 19843651
idiopathic generalized epilepsy; microdeletions; association; genetics
15.  Genome-wide association study of systemic sclerosis identifies CD247 as a novel susceptibility locus 
Nature genetics  2010;42(5):426-429.
Systemic sclerosis (SSc) is an autoimmune disease characterized by fibrosis of the skin and internal organs that leads to profound disability and premature death. To identify novel SSc susceptibility loci we conducted the first genome wide association study (GWAS) in a population of Caucasian ancestry including a total of 2296 SSc patients and 5171 controls. Analysis of 279,621 autosomal single nucleotide polymorphisms (SNPs) followed by replication testing in an independent case-control set of European ancestry (2,753 SSc patients / 4,569 controls) identified a new susceptibility locus for systemic sclerosis at CD247 (1q22-23; rs2056626, P = 2.09 × 10−7 in the discovery samples, P = 3.39 × 10−9 in the combined analysis). Additionally, we confirm and firmly establish the role of MHC (2.31 × 10−18), IRF5 (P =1.86 × 10−13) and STAT4 (P =3.37 × 10−9) gene regions as SSc genetic risk factors.
doi:10.1038/ng.565
PMCID: PMC2861917  PMID: 20383147
16.  Common Variation in ISL1 Confers Genetic Susceptibility for Human Congenital Heart Disease 
PLoS ONE  2010;5(5):e10855.
Congenital heart disease (CHD) is the most common birth abnormality and the etiology is unknown in the overwhelming majority of cases. ISLET1 (ISL1) is a transcription factor that marks cardiac progenitor cells and generates diverse multipotent cardiovascular cell lineages. The fundamental role of ISL1 in cardiac morphogenesis makes this an exceptional candidate gene to consider as a cause of complex congenital heart disease. We evaluated whether genetic variation in ISL1 fits the common variant–common disease hypothesis. A 2-stage case-control study examined 27 polymorphisms mapping to the ISL1 locus in 300 patients with complex congenital heart disease and 2,201 healthy pediatric controls. Eight genic and flanking ISL1 SNPs were significantly associated with complex congenital heart disease. A replication study analyzed these candidate SNPs in 1,044 new cases and 3,934 independent controls and confirmed that genetic variation in ISL1 is associated with risk of non-syndromic congenital heart disease. Our results demonstrate that two different ISL1 haplotypes contribute to risk of CHD in white and black/African American populations.
doi:10.1371/journal.pone.0010855
PMCID: PMC2877111  PMID: 20520780
17.  Linkage study of 14 candidate genes and loci in four large Dutch families with vesico-ureteral reflux 
Vesico-ureteral reflux (VUR) is a major contributing factor to end-stage renal disease in paediatric patients. Primary VUR is a familial disorder, but little is known about its genetic causes. To investigate the involvement of 12 functional candidate genes and two reported loci in VUR, we performed a linkage study in four large, Dutch, multi-generational families with multiple affected individuals. We were unable to detect linkage to any of the genes and loci and could exclude the GDNF, RET, SLIT2, SPRY1, PAX2, AGTR2, UPK1A and UPK3A genes and the 1p13 and 20p13 loci from linkage to VUR. Our results provide further evidence that there appears to be genetic heterogeneity in VUR.
Electronic supplementary material
The online version of this article (doi:10.1007/s00467-007-0492-4) contains supplementary material, which is available to authorized users.
doi:10.1007/s00467-007-0492-4
PMCID: PMC1915619  PMID: 17497182
Vesico-ureteral reflux/genetics; Kidney diseases/genetics; Kidney diseases/pathology; Linkage (genetics)

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