Showing papers by "Guy A. Rouleau published in 2016"
Children's Hospital of Eastern Ontario1, McGill University2, North York General Hospital3, McGill University Health Centre4, Alberta Children's Hospital5, Montreal Neurological Institute and Hospital6, Ottawa Hospital7, University of Toronto8, Université de Montréal9, Memorial University of Newfoundland10, University of Manitoba11, University of Calgary12, University of British Columbia13, University of Alberta14, Halifax15, University of Western Ontario16, McMaster University17
TL;DR: The analysis of this dataset showed that these known disease genes were not identified prior to WES enrollment for two key reasons: genetic heterogeneity associated with a clinical diagnosis and atypical presentation of known, clinically recognized diseases.
Abstract: An accurate diagnosis is an integral component of patient care for children with rare genetic disease. Recent advances in sequencing, in particular whole-exome sequencing (WES), are identifying the genetic basis of disease for 25-40% of patients. The diagnostic rate is probably influenced by when in the diagnostic process WES is used. The Finding Of Rare Disease GEnes (FORGE) Canada project was a nation-wide effort to identify mutations for childhood-onset disorders using WES. Most children enrolled in the FORGE project were toward the end of the diagnostic odyssey. The two primary outcomes of FORGE were novel gene discovery and the identification of mutations in genes known to cause disease. In the latter instance, WES identified mutations in known disease genes for 105 of 362 families studied (29%), thereby informing the impact of WES in the setting of the diagnostic odyssey. Our analysis of this dataset showed that these known disease genes were not identified prior to WES enrollment for two key reasons: genetic heterogeneity associated with a clinical diagnosis and atypical presentation of known, clinically recognized diseases. What is becoming increasingly clear is that WES will be paradigm altering for patients and families with rare genetic diseases.
308 citations
United States Department of Health and Human Services1, University of Göttingen2, Ludwig Maximilian University of Munich3, University of Bonn4, Charité5, Dokkyo Medical University6, University of Barcelona7, Karolinska University Hospital8, State University of Campinas9, Medical University of Graz10, University of California, San Diego11, Mayo Clinic12, Paris Diderot University13, McGill University Health Centre14, University of Queensland15, National Taiwan University16, University Hospital of Basel17, University of Adelaide18, Newcastle University19, Douglas Mental Health University Institute20, Poznan University of Medical Sciences21, Geneva College22, French Institute of Health and Medical Research23, Neuroscience Research Australia24, University of New South Wales25, Dalhousie University26, Johns Hopkins University27, Osaka University28, University of Lorraine29, Goethe University Frankfurt30, Hokkaido University31, University of Gothenburg32, Karolinska Institutet33, Veterans Health Administration34, University of Antioquia35, University of Calgary36, University of Cagliari37, Aarhus University38, University of Cincinnati39, University of Salerno40, University of Naples Federico II41, Nagoya University42, Harvard University43, Dresden University of Technology44, Montreal Neurological Institute and Hospital45, United States Department of Veterans Affairs46, National Institutes of Health47, Roy J. and Lucille A. Carver College of Medicine48, University of Iowa49, Heidelberg University50, University of Toronto51, RIKEN Brain Science Institute52
TL;DR: A genome-wide association study of lithium response in 2,563 patients collected by 22 participating sites from the International Consortium on Lithium Genetics (ConLiGen); the largest attempted so far finds a single locus of four linked SNPs on chromosome 21 met genome- wide significance criteria for association with lithium response.
258 citations
University of Massachusetts Medical School1, University Medical Center Utrecht2, University of Milan3, King's College London4, Trinity College, Dublin5, University of Turin6, Imperial College London7, University of Amsterdam8, Emory University9, Hospital General Universitario Gregorio Marañón10, Technische Universität München11, University of Southampton12, Macquarie University13, Brighton and Sussex Medical School14, University of Sydney15, Montreal Neurological Institute and Hospital16, University of Birmingham17, Queen Elizabeth Hospital Birmingham18, University of Oxford19, Mayo Clinic20, Katholieke Universiteit Leuven21, University of Würzburg22, Rafael Advanced Defense Systems23, Boğaziçi University24, University of Ulm25, Umeå University26
TL;DR: In a new screening strategy, gene-burden analyses trained with established ALS genes are performed and a significant association between loss-of-function (LOF) NEK1 variants and FALS risk is identified.
Abstract: To identify genetic factors contributing to amyotrophic lateral sclerosis (ALS), we conducted whole-exome analyses of 1,022 index familial ALS (FALS) cases and 7,315 controls. In a new screening strategy, we performed gene-burden analyses trained with established ALS genes and identified a significant association between loss-of-function (LOF) NEK1 variants and FALS risk. Independently, autozygosity mapping for an isolated community in the Netherlands identified a NEK1 p.Arg261His variant as a candidate risk factor. Replication analyses of sporadic ALS (SALS) cases and independent control cohorts confirmed significant disease association for both p.Arg261His (10,589 samples analyzed) and NEK1 LOF variants (3,362 samples analyzed). In total, we observed NEK1 risk variants in nearly 3% of ALS cases. NEK1 has been linked to several cellular functions, including cilia formation, DNA-damage response, microtubule stability, neuronal morphology and axonal polarity. Our results provide new and important insights into ALS etiopathogenesis and genetic etiology.
208 citations
National Institutes of Health1, Broad Institute2, Karolinska Institutet3, University of Gothenburg4, Charité5, Dalhousie University6, University of Cagliari7, University of Barcelona8, University of Geneva9, University of Chicago10, Portland VA Medical Center11, Dresden University of Technology12, University of Adelaide13, Paris Diderot University14, Medical University of Graz15, University of Pennsylvania16, University of California, San Diego17, Mayo Clinic18, Scripps Health19, University of California, San Francisco20, McGill University21, University of Bonn22, University of Basel23, University of Iowa24, Translational Genomics Research Institute25, Douglas Mental Health University Institute26, Johns Hopkins University27, Indiana University28, University of Paris29, Ludwig Maximilian University of Munich30, Neuroscience Research Australia31, University of New South Wales32, University of Göttingen33, Howard University34, University of Lorraine35, Goethe University Frankfurt36, Heidelberg University37, United States Department of Veterans Affairs38, University of Illinois at Chicago39, Seconda Università degli Studi di Napoli40, University of Cincinnati41, University of Michigan42, University of Salerno43, Washington University in St. Louis44, Rush University Medical Center45
TL;DR: A two-stage meta-analysis of GWAS of bipolar disorder patients and controls revealed genome-wide significant associations at two novel loci, adding to a growing list of common autosomal variants involved in BD and illustrating the power of comparing well-characterized cases to an excess of controls in GWAS.
Abstract: Bipolar disorder (BD) is a genetically complex mental illness characterized by severe oscillations of mood and behaviour. Genome-wide association studies (GWAS) have identified several risk loci that together account for a small portion of the heritability. To identify additional risk loci, we performed a two-stage meta-analysis of >9 million genetic variants in 9,784 bipolar disorder patients and 30,471 controls, the largest GWAS of BD to date. In this study, to increase power we used ∼2,000 lithium-treated cases with a long-term diagnosis of BD from the Consortium on Lithium Genetics, excess controls, and analytic methods optimized for markers on the X-chromosome. In addition to four known loci, results revealed genome-wide significant associations at two novel loci: an intergenic region on 9p21.3 (rs12553324, P = 5.87 × 10 - 9; odds ratio (OR) = 1.12) and markers within ERBB2 (rs2517959, P = 4.53 × 10 - 9; OR = 1.13). No significant X-chromosome associations were detected and X-linked markers explained very little BD heritability. The results add to a growing list of common autosomal variants involved in BD and illustrate the power of comparing well-characterized cases to an excess of controls in GWAS.
176 citations
University of Sydney1, Macquarie University2, King's College London3, University of Wollongong4, Stanford University5, Université de Montréal6, Montreal Neurological Institute and Hospital7, La Trobe University8, University of New South Wales9, Neuroscience Research Australia10, Mayo Clinic11, University of Tokyo12, Worcester Polytechnic Institute13, University of Massachusetts Medical School14, University of Birmingham15, Queen Elizabeth II Hospital16, Emory University17, Hospital General Universitario Gregorio Marañón18, Trinity College, Dublin19, University of Southampton20, University Hospitals Birmingham NHS Foundation Trust21, University of Milan22, Imperial College London23
TL;DR: In this article, the authors used genome-wide linkage analysis in a large ALS/FTD kindred to identify a novel disease locus on chromosome 16p13.3, which encodes cyclin F, a component of an E3 ubiquitin-protein ligase complex (SCFCyclin F).
Abstract: Amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) are overlapping, fatal neurodegenerative disorders in which the molecular and pathogenic basis remains poorly understood. Ubiquitinated protein aggregates, of which TDP-43 is a major component, are a characteristic pathological feature of most ALS and FTD patients. Here we use genome-wide linkage analysis in a large ALS/FTD kindred to identify a novel disease locus on chromosome 16p13.3. Whole-exome sequencing identified a CCNF missense mutation at this locus. Interrogation of international cohorts identified additional novel CCNF variants in familial and sporadic ALS and FTD. Enrichment of rare protein-altering CCNF variants was evident in a large sporadic ALS replication cohort. CCNF encodes cyclin F, a component of an E3 ubiquitin–protein ligase complex (SCFCyclin F). Expression of mutant CCNF in neuronal cells caused abnormal ubiquitination and accumulation of ubiquitinated proteins, including TDP-43 and a SCFCyclin F substrate. This implicates common mechanisms, linked to protein homeostasis, underlying neuronal degeneration.
166 citations
TL;DR: Rare homozygous and compound-heterozygous nonsense, missense, frameshift, and splice-site mutations in CAPN1 were identified in all affected individuals, and sequencing in additional family members confirmed the segregation of these mutations with the disease (spastic paraplegia 76).
Abstract: Hereditary spastic paraplegia (HSP) is a genetically and clinically heterogeneous disease characterized by spasticity and weakness of the lower limbs with or without additional neurological symptoms. Although more than 70 genes and genetic loci have been implicated in HSP, many families remain genetically undiagnosed, suggesting that other genetic causes of HSP are still to be identified. HSP can be inherited in an autosomal-dominant, autosomal-recessive, or X-linked manner. In the current study, we performed whole-exome sequencing to analyze a total of nine affected individuals in three families with autosomal-recessive HSP. Rare homozygous and compound-heterozygous nonsense, missense, frameshift, and splice-site mutations in CAPN1 were identified in all affected individuals, and sequencing in additional family members confirmed the segregation of these mutations with the disease (spastic paraplegia 76 [SPG76]). CAPN1 encodes calpain 1, a protease that is widely present in the CNS. Calpain 1 is involved in synaptic plasticity, synaptic restructuring, and axon maturation and maintenance. Three models of calpain 1 deficiency were further studied. In Caenorhabditis elegans, loss of calpain 1 function resulted in neuronal and axonal dysfunction and degeneration. Similarly, loss-of-function of the Drosophila melanogaster ortholog calpain B caused locomotor defects and axonal anomalies. Knockdown of calpain 1a, a CAPN1 ortholog in Danio rerio, resulted in abnormal branchiomotor neuron migration and disorganized acetylated-tubulin axonal networks in the brain. The identification of mutations in CAPN1 in HSP expands our understanding of the disease causes and potential mechanisms.
96 citations
TL;DR: SeZ6, RYR2, GPR153, GTF2IRD1, TTBK1 and ITGA6 have been previously linked to neuronal function or to psychiatric disorders, and thus may be considered as COS candidate genes.
Abstract: Childhood-onset schizophrenia (COS), defined by the onset of illness before age 13 years, is a rare severe neurodevelopmental disorder of unknown etiology. Recently, sequencing studies have identified rare, potentially causative de novo variants in sporadic cases of adult-onset schizophrenia and autism. In this study, we performed exome sequencing of 17 COS trios in order to test whether de novo variants could contribute to this disease. We identified 20 de novo variants in 17 COS probands, which is consistent with the de novo mutation rate reported in the adult form of the disease. Interestingly, the missense de novo variants in COS have a high likelihood for pathogenicity and were enriched for genes that are less tolerant to variants. Among the genes found disrupted in our study, SEZ6, RYR2, GPR153, GTF2IRD1, TTBK1 and ITGA6 have been previously linked to neuronal function or to psychiatric disorders, and thus may be considered as COS candidate genes.
74 citations
TL;DR: Clinical trials on GBA-associated PD are ongoing, and because treatment specifically targeting GBA is likely to be available in the future, it is important to determine whether the GBA p.T369M substitution is associated with PD.
Abstract: The lysosomal enzyme glucocerebrosidase (GCase), encoded by GBA, has an important role in Parkinson disease (PD). GBA mutation carriers have an increased risk for PD, earlier age at onset, faster progression, and various nonmotor symptoms including cognitive decline, REM sleep behavior disorder, hyposmia, and autonomic dysfunction.(1) Furthermore, GCase enzymatic activity is reduced in the peripheral blood(2) and brain(3) of noncarrier, sporadic PD patients. Biallelic GBA mutations, which have been classified as "severe" or "mild," may cause Gaucher disease (GD), a lysosomal storage disorder. Mild mutations may lead to GD type 1, and 2 severe mutations result in neuronopathic GD (type 2 and type 3).(4) There are 2 GBA variants, p.E326K and p.T369M, which do not cause GD in homozygous carriers, but may modify GCase activity and GD phenotype. It is now clear that p.E326K is a risk factor for PD,(5) but whether p.T369M is associated with PD is still controversial. In some studies, the p.T369M substitution was associated with PD,(6) while in others it had similar or increased frequency in controls. Of interest, it was recently demonstrated that the GBA p.T369M substitution was associated with reduced enzymatic activity in patients with PD and controls compared with that in noncarriers (7.64 vs 11.93 μmol/L/h, p < 0.001).(2) Of interest, it was even lower than the average enzymatic activity of the p.E326K substitution, which was 9.81 μmol/L/h. Because clinical trials on GBA-associated PD are ongoing, and because treatment specifically targeting GBA is likely to be available in the future, it is important to determine whether the GBA p.T369M substitution is associated with PD.
72 citations
University of Kiel1, Université du Québec à Chicoutimi2, Montreal Neurological Institute and Hospital3, Auburn University4, University of Würzburg5, Columbia University6, Mayo Clinic7, National Institutes of Health8, Ludwig Maximilian University of Munich9, Carlos III Health Institute10, University of Barcelona11, Innsbruck Medical University12, University of Saskatchewan13, German Center for Neurodegenerative Diseases14, Baylor College of Medicine15, University of British Columbia16, Montreal General Hospital17, Montreal Children's Hospital18, Laval University19, Université de Montréal20, Technische Universität München21, Virginia Commonwealth University22, Yale University23
TL;DR: A genome-wide association study in more than 2800 patients with essential tremor and more than 6800 controls of European descent is conducted, and three new loci associated with the disease are identified.
Abstract: We conducted a genome-wide association study of essential tremor, a common movement disorder characterized mainly by a postural and kinetic tremor of the upper extremities. Twin and family history studies show a high heritability for essential tremor. The molecular genetic determinants of essential tremor are unknown. We included 2807 patients and 6441 controls of European descent in our two-stage genome-wide association study. The 59 most significantly disease-associated markers of the discovery stage were genotyped in the replication stage. After Bonferroni correction two markers, one (rs10937625) located in the serine/threonine kinase STK32B and one (rs17590046) in the transcriptional coactivator PPARGC1A were associated with essential tremor. Three markers (rs12764057, rs10822974, rs7903491) in the cell-adhesion molecule CTNNA3 were significant in the combined analysis of both stages. The expression of STK32B was increased in the cerebellar cortex of patients and expression quantitative trait loci database mining showed association between the protective minor allele of rs10937625 and reduced expression in cerebellar cortex. We found no expression differences related to disease status or marker genotype for the other two genes. Replication of two lead single nucleotide polymorphisms of previous small genome-wide association studies (rs3794087 in SLC1A2, rs9652490 in LINGO1) did not confirm the association with essential tremor.
70 citations
TL;DR: The MATR3 mutation frequency in French-Canadian ALS and control individuals was assessed and showed that MATR 3 mutations were found in 0%, 1.8%, and 0% of FALS, SALS, and controls, respectively.
58 citations
TL;DR: It appears that the function of RNF213 can be differently altered to predispose distinct populations to dissimilar neurovascular conditions, highlighting the importance of a population's background in genetic studies of heterogeneous disease.
Abstract: Intracranial aneurysms (IAs) are the result of focal weakness in the artery wall and have a complex genetic makeup. To date, genome-wide association and sequencing studies have had limited success in identifying IA risk factors. Distinct populations, such as the French-Canadian (FC) population, have increased IA prevalence. In our study, we used exome sequencing to prioritize risk variants in a discovery cohort of six FC families affected by IA, and the analysis revealed an increased variation burden for ring finger protein 213 (RNF213). We resequenced RNF213 in a larger FC validation cohort, and association tests on further identified variants supported our findings (SKAT-O, p = 0.006). RNF213 belongs to the AAA+ protein family, and two variants (p.Arg2438Cys and p.Ala2826Thr) unique to affected FC individuals were found to have increased ATPase activity, which could lead to increased risk of IA by elevating angiogenic activities. Common SNPs in RNF213 were also extracted from the NeuroX SNP-chip genotype data, comprising 257 FC IA-affected and 1,988 control individuals. We discovered that the non-ancestral allele of rs6565666 was significantly associated with the affected individuals (p = 0.03), and it appeared as though the frequency of the risk allele had changed through genetic drift. Although RNF213 is a risk factor for moyamoya disease in East Asians, we demonstrated that it might also be a risk factor for IA in the FC population. It therefore appears that the function of RNF213 can be differently altered to predispose distinct populations to dissimilar neurovascular conditions, highlighting the importance of a population’s background in genetic studies of heterogeneous disease.
TL;DR: It is interesting to note that as the number of ALS genes grows, many of the proteins they encode are in shared intracellular processes.
Abstract: Amyotrophic lateral sclerosis (ALS) is a fatal disorder that is characterized by a progressive degeneration of the upper and lower motor neurons. Most cases appear to be sporadic, but 5–10 % of cases have a family history of the disease. High-throughput DNA sequencing and related genomic capture tools are methodological advances which have rapidly contributed to an acceleration in the discovery of genetic risk factors for both familial and sporadic ALS. It is interesting to note that as the number of ALS genes grows, many of the proteins they encode are in shared intracellular processes. This review will summarize some of the recent advances and gene discovery made in ALS.
TL;DR: It is suggested that variants affecting the function of SPG7 are the fourth most common form of recessive ataxia in FC patients and that this gene should be considered in unresolved patients.
Abstract: Hereditary cerebellar ataxias and hereditary spastic paraplegias are clinically and genetically heterogeneous and often overlapping neurological disorders. Mutations in SPG7 cause the autosomal recessive spastic paraplegia type 7 (SPG7), but recent studies indicate that they are also one of the most common causes of recessive cerebellar ataxia. In Quebec, a significant number of patients affected with cerebellar ataxia and spasticity remain without a molecular diagnosis. We performed whole-exome sequencing in three French Canadian (FC) patients affected with spastic ataxia and uncovered compound heterozygous variants in SPG7 in all three. Sanger sequencing of SPG7 exons and exon/intron boundaries was used to screen additional patients. In total, we identified recessive variants in SPG7 in 22 FC patients belonging to 12 families (38.7% of the families screened), including two novel variants. The p.(Ala510Val) variant was the most common in our cohort. Cerebellar features, including ataxia, were more pronounced than spasticity in this cohort. These results strongly suggest that variants affecting the function of SPG7 are the fourth most common form of recessive ataxia in FC patients. Thus, we propose that SPG7 mutations explain a significant proportion of FC spastic ataxia cases and that this gene should be considered in unresolved patients.
TL;DR: The results provide some support for the possibility that specific DNAJC13 variants may play a minor role in PD susceptibility, although studies in additional populations are necessary.
TL;DR: Retention of the repeat-containing intron in mature C9orf72 mRNA can potentially explain nuclear foci formation as well as nuclear export of GGGGCC repeat RNA and suggests that the misprocessing of C9or72 transcripts initiates the pathogenic process caused by C9orc72 hexanucleotide repeat expansions as wellAs provides the basis for novel therapeutic strategies.
Abstract: The most common forms of amyotrophic lateral sclerosis and frontotemporal dementia are caused by a large GGGGCC repeat expansion in the first intron of the C9orf72 gene. The repeat-containing intron should be degraded after being spliced out, however GGGGCC repeat-containing RNA species either accumulate in nuclear foci or are exported to the cytoplasm where they are translated into potentially toxic dipeptide repeat proteins by repeat-associated non-AUG-initiated (RAN) translation. In order to determine the mechanisms of repeat-containing intron misprocessing, we have analyzed C9orf72 transcripts in lymphoblasts from C9orf72 expansion carriers (n = 15) and control individuals (n = 15). We have identified polyadenylated C9orf72 RNA species retaining the repeat-containing intron and in which downstream exons are spliced correctly resulting in a C9orf72 mRNA with an enlarged 5’-UTR containing the GGGGCC repeats. Intron-retaining transcripts are produced from both wild-type and mutant alleles. Intron-retaining C9orf72 transcripts were also detected in brain with a 2.7 fold increase measured in the frontal cortex from heterozygous expansion carriers (n = 11) compared to controls (n = 10). The level of intron-retaining transcripts was increased 5.9 fold in a case homozygous for the expansion. We also show that a large proportion of intron 1-retaining C9orf72 transcripts accumulate in the nucleus. Retention of the repeat-containing intron in mature C9orf72 mRNA can potentially explain nuclear foci formation as well as nuclear export of GGGGCC repeat RNA and suggests that the misprocessing of C9orf72 transcripts initiates the pathogenic process caused by C9orf72 hexanucleotide repeat expansions as well as provides the basis for novel therapeutic strategies.
TL;DR: There is a strong positive correlation between paternal age and germline DNM in healthy subjects and it is observed that germline CNVs do not follow the same trend, suggesting a different mechanism.
Abstract: De novo mutations (DNM) are an important source of rare variants and are increasingly being linked to the development of many diseases. Recently, the paternal age effect has been the focus of a number of studies that attempt to explain the observation that increasing paternal age increases the risk for a number of diseases. Using disease-free familial quartets we show that there is a strong positive correlation between paternal age and germline DNM in healthy subjects. We also observed that germline CNVs do not follow the same trend, suggesting a different mechanism. Finally, we observed that DNM were not evenly distributed across the genome, which adds support to the existence of DNM hotspots.
TL;DR: This case report supports the association of CHD8 mutations with classical autism, macrocephaly, infantile hypotonia, speech delay, lack of major ID, and psychopathology in late adolescence caused by insufficient dosage ofCHD8.
Abstract: Mutations in chromodomain helicase DNA-binding domain 8 (CHD8) have been identified in independent genotyping studies of autism spectrum disorder. To better understand the phenotype associated with CHD8 mutations, we genotyped all CHD8 exons in carefully assessed cohorts of autism (n = 142), schizophrenia (SCZ; n = 143), and intellectual disability (ID; n = 94). We identified one frameshift mutation, seven non-synonymous variants, and six synonymous variants. The frameshift mutation, p.Asn2092Lysfs*2, which creates a premature stop codon leading to the loss of 212 amino acids of the protein, was from an autism case on whom we present multiple clinical assessments and pharmacological treatments spanning more than 10 years. RNA and protein analysis support a model where the transcript generated from the mutant allele results in haploinsufficiency of CHD8. This case report supports the association of CHD8 mutations with classical autism, macrocephaly, infantile hypotonia, speech delay, lack of major ID, and psychopathology in late adolescence caused by insufficient dosage of CHD8. Review of 16 other CHD8 mutation cases suggests that clinical features and their severity vary considerably across individuals; however, these data support a CHD8 mutation syndrome, further highlighting the importance of genomic medicine to guide clinical assessment and treatment.
TL;DR: These data are the first to describe a functional missense variant in SLC12A2 in human SCZ, and suggest that genetically encoded dysregulation of NKCC1 may be a risk factor for, or contribute to the pathogenesis of, humanSCZ.
TL;DR: In the nerve injury model of neuropathic pain, WNK1/HSN2 contributed to a maladaptive decrease in the activity of the K+-Cl− cotransporter KCC2 by increasing its inhibitory phosphorylation at Thr906 and Thr1007, resulting in an associated loss of GABA (γ-aminobutyric acid)–mediated inhibition of spinal pain-transmitting nerves.
Abstract: HSN2is a nervous system predominant exon of the gene encoding the kinase WNK1 and is mutated in an autosomal recessive, inherited form of congenital pain insensitivity. The HSN2-containing splice variant is referred to as WNK1/HSN2. We created a knockout mouse specifically lacking theHsn2exon ofWnk1 Although these mice had normal spinal neuron and peripheral sensory neuron morphology and distribution, the mice were less susceptible to hypersensitivity to cold and mechanical stimuli after peripheral nerve injury. In contrast, thermal and mechanical nociceptive responses were similar to control mice in an inflammation-induced pain model. In the nerve injury model of neuropathic pain, WNK1/HSN2 contributed to a maladaptive decrease in the activity of the K(+)-Cl(-)cotransporter KCC2 by increasing its inhibitory phosphorylation at Thr(906)and Thr(1007), resulting in an associated loss of GABA (γ-aminobutyric acid)-mediated inhibition of spinal pain-transmitting nerves. Electrophysiological analysis showed that WNK1/HSN2 shifted the concentration of Cl(-)such that GABA signaling resulted in a less hyperpolarized state (increased neuronal activity) rather than a more hyperpolarized state (decreased neuronal activity) in mouse spinal nerves. Pharmacologically antagonizing WNK activity reduced cold allodynia and mechanical hyperalgesia, decreased KCC2 Thr(906)and Thr(1007)phosphorylation, and restored GABA-mediated inhibition (hyperpolarization) of injured spinal cord lamina II neurons. These data provide mechanistic insight into, and a compelling therapeutic target for treating, neuropathic pain after nerve injury.
TL;DR: The results support an association between SCARB2 genotype at rs6812193 and PD, but suggest that the increased risk is not mediated by GCase activity.
Abstract: Mutations in glucocerebrosidase (GBA) are a common risk factor for Parkinson's disease (PD). The scavenger receptor class B member 2 (SCARB2) gene encodes a receptor responsible for the transport of glucocerebrosidase (GCase) to the lysosome. Two common SNPs in linkage disequilibrium with SCARB2, rs6812193 and rs6825004, have been associated with PD and Lewy Body Disease in genome wide association studies. Whether these SNPs are associated with altered glucocerebrosidase enzymatic activity is unknown. Our objective was to determine whether SCARB2 SNPs are associated with PD and with reduced GCase activity. The GBA gene was fully sequenced, and the LRRK2 G2019S and SCARB2 rs6812193 and rs6825004 SNPs were genotyped in 548 PD patients and 272 controls. GCase activity in dried blood spots was measured by tandem mass spectrometry. We tested the association between SCARB2 genotypes and PD risk in regression models adjusted for gender, age, and LRRK2 G2019S and GBA mutation status. We compared GCase activity between participants with different genotypes at rs6812193 and rs6825004. Genotype at rs6812193 was associated with PD status. PD cases were less likely to carry the T allele than the C allele (OR=0.71; p=0.004), but GCase enzymatic activity was similar across rs6812193 genotypes (C/C: 11.88 μmol/l/h; C/T: 11.80 μmol/l/h; T/T: 12.02 μmol/l/h; p=0.867). Genotype at rs6825004 was not associated with either PD status or GCase activity. In conclusion, our results support an association between SCARB2 genotype at rs6812193 and PD, but suggest that the increased risk is not mediated by GCase activity.
TL;DR: Disruption of TBC1D4 is common among North American Inuit, resulting in exclusively elevated postprandial glucose, leading to underdiagnosis of type 2 diabetes, unless an OGTT is performed.
Abstract: Objective A common nonsense mutation in TBC1D4 was recently found to substantially increase the odds of type 2 diabetes in Greenlandic Inuit, leading to exclusively increased postprandial glucose. We investigated the frequency and effect of the TBC1D4 mutation on glucose metabolism and type 2 diabetes diagnosis among Canadian and Alaskan Inuit. Research Design and Methods Exome sequencing of the TBC1D4 variant was performed in 114 Inuit from Nunavik, Canada, and Sanger sequencing was undertaken in 1,027 Alaskan Inuit from the Genetics of Coronary Artery Disease in Alaska Natives (GOCADAN) Study. Association testing evaluated the effect of the TBC1D4 variant on diabetes-related metabolic traits and diagnosis. Results The TBC1D4 mutation was present in 27% of Canadian and Alaskan Inuit. It was strongly associated with higher glucose (effect size +3.3 mmol/L; P = 2.5 x10−6) and insulin (effect size +175 pmol/L; P = 0.04) 2 h after an oral glucose load in homozygote carriers. TBC1D4 carriers with prediabetes and type 2 diabetes had an increased risk of remaining undiagnosed unless postprandial glucose values were tested (odds ratio 5.4 [95% CI 2.5–12]) compared with noncarriers. Of carriers with prediabetes or type 2 diabetes, 32% would remain undiagnosed without an oral glucose tolerance test (OGTT). Conclusions Disruption of TBC1D4 is common among North American Inuit, resulting in exclusively elevated postprandial glucose. This leads to underdiagnosis of type 2 diabetes, unless an OGTT is performed. Accounting for genetic factors in the care of Inuit with diabetes provides an opportunity to implement precision medicine in this population.
University of California, Los Angeles1, Harvard University2, Vanderbilt University Medical Center3, Democritus University of Thrace4, University of Denver5, University of Toronto6, Johns Hopkins University School of Medicine7, University of Bonn8, University of Duisburg-Essen9, Yale University10, Université de Montréal11, McGill University12, Hofstra University13, University of Strasbourg14, French Institute of Health and Medical Research15, Hannover Medical School16, Medical University of Vienna17, Cold Spring Harbor Laboratory18, University of Utah19, Semmelweis University20, Children's Mercy Hospital21, University of Catania22, Utrecht University23, Medical University of Warsaw24, Pennsylvania State University25, University of Florida26, Marquette University27, Cardiff University28, SUNY Downstate Medical Center29, University of Southern California30, VU University Amsterdam31
TL;DR: A European ancestry sample composed of 2,435 TS cases and 4,100 controls for copy-number variants using SNP microarrays was examined and identified two genome-wide significant loci that confer a substantial increase in risk for TS.
Abstract: Tourette syndrome (TS) is highly heritable, although identification of its underlying genetic cause(s) has remained elusive. We examined a European ancestry sample composed of 2,435 TS cases and 4,100 controls for copy-number variants (CNVs) using SNP microarrays and identified two genome-wide significant loci that confer a substantial increase in risk for TS (NRXN1, OR=20.3, 95%CI [2.6-156.2], p=6.0 × 10-6; CNTN6, OR=10.1, 95% CI [2.3-45.4], p=3.7 × 10-5). Approximately 1% of TS cases carried one of these CNVs, indicating that rare structural variation contributes significantly to the genetic architecture of TS.
TL;DR: In a cohort of patients with young‐onset Parkinson's disease, the authors assessed the prevalence of genetic mutations in those who enrolled in deep brain stimulation (DBS) programs compared with those who did not enroll DBS programs.
Abstract: Objective
In a cohort of patients with young-onset Parkinson's disease (PD), the authors assessed (1) the prevalence of genetic mutations in those who enrolled in deep brain stimulation (DBS) programs compared with those who did not enroll DBS programs and (2) specific genetic and clinical predictors of DBS enrollment.
Methods
Subjects were participants from 3 sites (Columbia University, Rush University, and the University of Pennsylvania) in the Consortium on Risk for Early Onset Parkinson's Disease (CORE-PD) who had an age at onset < 51 years. The analyses presented here focus on glucocerebrosidase (GBA), leucine-rich repeat kinase 2 (LRRK2), and parkin (PRKN) mutation carriers. Mutation carrier status, demographic data, and disease characteristics in individuals who did and did not enroll in DBS were analyzed. The association between mutation status and DBS placement was assessed in logistic regression models.
Results
Patients who had PD with either GBA, LRRK2, or PRKN mutations were more common in the DBS group (n = 99) compared with the non-DBS group (n = 684; 26.5% vs. 16.8%, respectively; P = 0.02). In a multivariate logistic regression model, GBA mutation status (odds ratio, 2.1; 95% confidence interval, 1.0–4.3; P = 0.05) was associated with DBS surgery enrollment. However, when dyskinesia was included in the multivariate logistic regression model, dyskinesia had a strong association with DBS placement (odds ratio, 3.8; 95% confidence interval, 1.9–7.3; P < 0.0001), whereas the association between GBA mutation status and DBS placement did not persist (P = 0.25).
Conclusions
DBS populations are enriched with genetic mutation carriers. The effect of genetic mutation carriers on DBS outcomes warrants further exploration.
TL;DR: A patient carrying p.P525L FUS mutation and experiencing an aggressive course of ALS presenting with dysphonia and diplopia is reported.
Abstract: Juvenile amyotrophic lateral sclerosis (jALS) is characterized by progressive upper and lower motor neuron degeneration leading to facial muscle spasticity, spastic dysarthria, and spastic gait with an early onset (before 25 years old). Unlike adult-onset amyotrophic lateral sclerosis (ALS), patients with jALS tend to have slower progression of motor neuron disease and prolonged survival to a normal life expectancy. Mutations in FUS gene have been reported in jALS,(1) including p.P525L mutation that has been consistently associated with early onset and aggressive presentation.(2) Here, we report a patient carrying p.P525L FUS mutation and experiencing an aggressive course of ALS presenting with dysphonia and diplopia.
TL;DR: It is found that locomotor defects found in all of the spastin models could be partially rescued by phenazine, methylene blue, N-acetyl-cysteine, guanabenz and salubrinal, and it is shown that established biomarkers of ER stress levels correlated with improved locomotor activity upon treatment across model organisms.
Abstract: Hereditary spastic paraplegias (HSPs) are a group of neurodegenerative diseases causing progressive gait dysfunction. Over 50 genes have now been associated with HSP. Despite the recent explosion in genetic knowledge, HSP remains without pharmacological treatment. Loss-of-function mutation of the SPAST gene, also known as SPG4, is the most common cause of HSP in patients. SPAST is conserved across animal species and regulates microtubule dynamics. Recent studies have shown that it also modulates endoplasmic reticulum (ER) stress. Here, utilizing null SPAST homologues in C. elegans, Drosophila and zebrafish, we tested FDA-approved compounds known to modulate ER stress in order to ameliorate locomotor phenotypes associated with HSP. We found that locomotor defects found in all of our spastin models could be partially rescued by phenazine, methylene blue, N-acetyl-cysteine, guanabenz and salubrinal. In addition, we show that established biomarkers of ER stress levels correlated with improved locomotor activity upon treatment across model organisms. Our results provide insights into biomarkers and novel therapeutic avenues for HSP.
TL;DR: These findings contribute to previous work showing dysregulation of Synapsins, particularly SYN2, in mood disorders and improve the understanding of the regulatory mechanisms that precipitate these changes likely leading to the BD or MDD phenotype.
Abstract: The Synapsins (SYN1, SYN2, and SYN3) are important players in the adult brain, given their involvement in synaptic transmission and plasticity, as well as in the developing brain through roles in axon outgrowth and synaptogenesis. We and others previously reported gene expression dysregulation, both as increases and decreases, of Synapsins in mood disorders, but little is known about the regulatory mechanisms leading to these differences. Thus, we proposed to study DNA methylation at theses genes’ promoter regions, under the assumption that altered epigenetic marks at key regulatory sites would be the cause of gene expression changes and thus part of the mood disorder etiology. We performed CpG methylation mapping focusing on the three genes’ predicted CpG islands using the Sequenom EpiTYPER platform. DNA extracted from post-mortem brain tissue (BA10) from individuals who had lived with bipolar disorder (BD), major depressive disorder (MDD), as well as psychiatrically healthy individuals was used. Differences in methylation across all CpGs within a CpG island and between the three diagnostic groups were assessed by 2-way mixed model analyses of variance. We found no significant results for SYN1 or SYN3, but there was a significant group difference in SYN2 methylation, as well as an overall pattern of hypomethylation across the CpG island. Furthermore, we found a significant inverse correlation of DNA methylation with SYN2a mRNA expression. These findings contribute to previous work showing dysregulation of Synapsins, particularly SYN2, in mood disorders and improve our understanding of the regulatory mechanisms that precipitate these changes likely leading to the BD or MDD phenotype.
TL;DR: Exome sequencing on three acallosal siblings from the same non-consanguineous family and identified compound heterozygous variants, p.[Gly94Arg];[Asn1232Ser], in the protein encoded by the CDK5RAP2 gene, also known as MCPH3, a gene previously reported to cause autosomal recessive primary microcephaly suggest a novel role for this gene in the pathogenesis of isolated ACC.
Abstract: Agenesis of the corpus callosum (ACC) is a common brain malformation which can be observed either as an isolated condition or as part of numerous congenital syndromes. Therefore, cognitive and neurological involvements in patients with ACC are variable, from mild linguistic and behavioral impairments to more severe neurological deficits. To date, the underlying genetic causes of isolated ACC remains elusive and causative genes have yet to be identified. We performed exome sequencing on three acallosal siblings from the same non-consanguineous family and identified compound heterozygous variants, p.[Gly94Arg];[Asn1232Ser], in the protein encoded by the CDK5RAP2 gene, also known as MCPH3, a gene previously reported to cause autosomal recessive primary microcephaly. Our findings suggest a novel role for this gene in the pathogenesis of isolated ACC.
TL;DR: A new publicly accessible web-service, RiboSoft, is presented, which implements a comprehensive hammerhead ribozyme design procedure, which takes into consideration multiple objectives leading to a multi-objective ranking of the computer-generated ribozymes.
Abstract: We present a new publicly accessible web-service, RiboSoft, which implements a comprehensive hammerhead ribozyme design procedure. It accepts as input a target sequence (and some design parameters) then generates a set of ranked hammerhead ribozymes, which target the input sequence. This paper describes the implemented procedure, which takes into consideration multiple objectives leading to a multi-objective ranking of the computer-generated ribozymes. Many ribozymes were assayed and validated, including four ribozymes targeting the transcript of a disease-causing gene (a mutant version of PABPN1). These four ribozymes were successfully tested in vitro and in vivo, for their ability to cleave the targeted transcript. The wet-lab positive results of the test are presented here demonstrating the real-world potential of both hammerhead ribozymes and RiboSoft. RiboSoft is freely available at the website http://ribosoft.fungalgenomics.ca/ribosoft/.
United States Department of Health and Human Services1, Karolinska Institutet2, University of Gothenburg3, Charité4, Dalhousie University5, University of Cagliari6, University of Barcelona7, Geneva College8, Karolinska University Hospital9, University of Chicago10, Veterans Health Administration11, Dresden University of Technology12, University of Adelaide13, Paris Diderot University14, Medical University of Graz15, University of Pennsylvania16, University of California, San Diego17, Mayo Clinic18, Scripps Health19, University of California, San Francisco20, McGill University Health Centre21, University Hospital of Basel22, University of Iowa Hospitals and Clinics23, Translational Genomics Research Institute24, McGill University25, Poznan University of Medical Sciences26, University of Bonn27, Johns Hopkins University28, Indiana University29, University of Paris30, Ludwig Maximilian University of Munich31, Neuroscience Research Australia32, University of Basel33, Howard University34, University of Lorraine35, National Institutes of Health36, Goethe University Frankfurt37, Heidelberg University38, University of Illinois at Chicago39, University of Naples Federico II40, University of Cincinnati41, University of Michigan42, University of New South Wales43, University of Salerno44, University of Iowa45, Washington University in St. Louis46, Rush University Medical Center47
TL;DR: The results add to a growing list of common autosomal variants involved in BD and illustrate the power of comparing well-characterized cases to an excess of controls in GWAS.
Abstract: Bipolar disorder (BD) is a genetically complex mental illness characterized by severe oscillations of mood and behavior. Genome-wide association studies (GWAS) have identified several risk loci that together account for a small portion of the heritability. To identify additional risk loci, we performed a two-stage meta-analysis of >9 million genetic variants in 9,784 bipolar disorder patients and 30,471 controls, the largest GWAS of BD to date. In this study, to increase power we used ~2,000 lithium-treated cases with a long-term diagnosis of BD from the Consortium on Lithium Genetics, excess controls, and analytic methods optimized for markers on the X-chromosome. In addition to four known loci, results revealed genome-wide significant associations at two novel loci: an intergenic region on 9p21.3 (rs12553324, p = 5.87×10-9; odds ratio = 1.12) and markers within ERBB2 (rs2517959, p = 4.53×10-9; odds ratio = 1.13). No significant X-chromosome associations were detected and X-linked markers explained very little BD heritability. The results add to a growing list of common autosomal variants involved in BD and illustrate the power of comparing well-characterized cases to an excess of controls in GWAS.
McGill University1, Montreal Neurological Institute and Hospital2, Université de Montréal3, Laval University4, Tomsk State University5, Pierre-and-Marie-Curie University6, Innsbruck Medical University7, university of lille8, Université du Québec à Montréal9, Montreal General Hospital10, French Institute of Health and Medical Research11, Columbia University12
TL;DR: The present study does not support a role for the MC1R p.R160W and other variants in susceptibility for PD or RBD and removes one study that introduced the heterogeneity.