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Muhtaseb AW, Duan J. Modeling common and rare genetic risk factors of neuropsychiatric disorders in human induced pluripotent stem cells. Schizophr Res 2022:S0920-9964(22)00156-6. [PMID: 35459617 PMCID: PMC9735430 DOI: 10.1016/j.schres.2022.04.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/14/2022] [Revised: 04/05/2022] [Accepted: 04/07/2022] [Indexed: 12/13/2022]
Abstract
Recent genome-wide association studies (GWAS) and whole-exome sequencing of neuropsychiatric disorders, especially schizophrenia, have identified a plethora of common and rare disease risk variants/genes. Translating the mounting human genetic discoveries into novel disease biology and more tailored clinical treatments is tied to our ability to causally connect genetic risk variants to molecular and cellular phenotypes. When combined with the Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)/CRISPR-associated (Cas) nuclease-mediated genome editing system, human induced pluripotent stem cell (hiPSC)-derived neural cultures (both 2D and 3D organoids) provide a promising tractable cellular model for bridging the gap between genetic findings and disease biology. In this review, we first conceptualize the advances in understanding the disease polygenicity and convergence from the past decade of iPSC modeling of different types of genetic risk factors of neuropsychiatric disorders. We then discuss the major cell types and cellular phenotypes that are most relevant to neuropsychiatric disorders in iPSC modeling. Finally, we critically review the limitations of iPSC modeling of neuropsychiatric disorders and outline the need for implementing and developing novel methods to scale up the number of iPSC lines and disease risk variants in a systematic manner. Sufficiently scaled-up iPSC modeling and a better functional interpretation of genetic risk variants, in combination with cutting-edge CRISPR/Cas9 gene editing and single-cell multi-omics methods, will enable the field to identify the specific and convergent molecular and cellular phenotypes in precision for neuropsychiatric disorders.
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Affiliation(s)
- Abdurrahman W Muhtaseb
- Center for Psychiatric Genetics, NorthShore University HealthSystem, Evanston, IL 60201, United States of America; Department of Human Genetics, The University of Chicago, Chicago, IL 60637, United States of America
| | - Jubao Duan
- Center for Psychiatric Genetics, NorthShore University HealthSystem, Evanston, IL 60201, United States of America; Department of Psychiatry and Behavioral Neuroscience, The University of Chicago, Chicago, IL 60637, United States of America.
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2
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Frye RE, Cakir J, Rose S, Delhey L, Bennuri SC, Tippett M, Melnyk S, James SJ, Palmer RF, Austin C, Curtin P, Arora M. Prenatal air pollution influences neurodevelopment and behavior in autism spectrum disorder by modulating mitochondrial physiology. Mol Psychiatry 2021; 26:1561-1577. [PMID: 32963337 PMCID: PMC8159748 DOI: 10.1038/s41380-020-00885-2] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/09/2020] [Revised: 08/03/2020] [Accepted: 09/08/2020] [Indexed: 02/07/2023]
Abstract
We investigate the role of the mitochondrion, an organelle highly sensitive to environmental agents, in the influence of prenatal air pollution exposure on neurodevelopment and behavior in 96 children with autism spectrum disorder (ASD) [45 with neurodevelopmental regression (NDR); 76% Male; mean (SD) age 10 y 9 m (3 y 9 m)]. Mitochondrial function was assessed using the Seahorse XFe96 in fresh peripheral blood mononuclear cells. Second and third trimester average and maximal daily exposure to fine air particulate matter of diameter ≤2.5 µm (PM2.5) was obtained from the Environmental Protection Agency's Air Quality System. Neurodevelopment was measured using the Vineland Adaptive Behavior Scale 2nd edition and behavior was assessed using the Aberrant Behavior Checklist and Social Responsiveness Scale. Prenatal PM2.5 exposure influenced mitochondrial respiration during childhood, but this relationship was different for those with (r = 0.25-0.40) and without (r = -0.07 to -0.19) NDR. Mediation analysis found that mitochondrial respiration linked to energy production accounted for 25% (SD = 2%) and 10% (SD = 2%) of the effect of average prenatal PM2.5 exposure on neurodevelopment and behavioral symptoms, respectively. Structural equation models estimated that PM2.5 and mitochondrial respiration accounted for 34% (SD = 4%) and 36% (SD = 3%) of the effect on neurodevelopment, respectively, and that behavior was indirectly influenced by mitochondrial respiration through neurodevelopment but directly influenced by prenatal PM2.5. Our results suggest that prenatal exposure to PM2.5 disrupts neurodevelopment and behavior through complex mechanisms, including long-term changes in mitochondrial respiration and that patterns of early development need to be considered when studying the influence of environmental agents on neurodevelopmental outcomes.
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Affiliation(s)
- Richard E Frye
- Barrow Neurological Institute at Phoenix Children's Hospital, Phoenix, AZ, USA.
| | - Janet Cakir
- North Carolina State University, Raleigh, NC, USA
| | - Shannon Rose
- Arkansas Children's Research Institute, Little Rock, AR, USA
- Department of Pediatrics, University of Arkansas for Medical Sciences, Little Rock, AR, USA
| | - Leanna Delhey
- Arkansas Children's Research Institute, Little Rock, AR, USA
- College of Public Health, University of Arkansas for Medical Sciences, Little Rock, AR, USA
| | - Sirish C Bennuri
- Arkansas Children's Research Institute, Little Rock, AR, USA
- Department of Pediatrics, University of Arkansas for Medical Sciences, Little Rock, AR, USA
| | - Marie Tippett
- Arkansas Children's Research Institute, Little Rock, AR, USA
- Department of Pediatrics, University of Arkansas for Medical Sciences, Little Rock, AR, USA
| | - Stepan Melnyk
- Arkansas Children's Research Institute, Little Rock, AR, USA
| | - S Jill James
- Arkansas Children's Research Institute, Little Rock, AR, USA
| | - Raymond F Palmer
- Department of Family and Community Medicine, University of Texas Health Science Center, San Antonio, TX, USA
| | - Christine Austin
- Department of Environmental Medicine and Public Health, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Paul Curtin
- Department of Environmental Medicine and Public Health, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Manish Arora
- Department of Environmental Medicine and Public Health, Icahn School of Medicine at Mount Sinai, New York, NY, USA
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Maghbooli M, Ghaffarpour M, Ghazizadeh T, Shalbaf NA, MalekMahmoudi G. Clinicogenetical Variants of Progressive External Ophthalmoplegia - An Especial Review of Non-ophthalmic Manifestations. Neurol India 2020; 68:760-768. [PMID: 32859811 DOI: 10.4103/0028-3886.293454] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
Progressive external ophthalmoplegia (PEO) is a slowly progressive myopathy characterized by extraocular muscles involvement, leading to frozen eyes without diplopia. The pattern of inheritance may be mitochondrial, autosomal dominant or, rarely, autosomal recessive. Sporadic forms were also reported. Muscular involvement other than extraocular muscles may occur with varying degrees of weakness, but this mostly happens many years after the disease begins. There are also scattered data about systemic signs besides ophthalmoplegia. This article aims to review non-ophthalmic findings of PEO from a clinicogenetical point of view.
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Affiliation(s)
- Mehdi Maghbooli
- Department of Neurology, Zanjan University of Medical Sciences, Vali-e-Asr Hospital, Zanjan, Iran
| | - Majid Ghaffarpour
- Department of Neurology, Tehran University of Medical Sciences, Iranian Center of Neurological Research, Tehran, Iran
| | - Taher Ghazizadeh
- Department of Neurology, Zanjan University of Medical Sciences, Vali-e-Asr Hospital, Zanjan, Iran
| | - Nazanin Azizi Shalbaf
- Department of Neurology, Zanjan University of Medical Sciences, Vali-e-Asr Hospital, Zanjan, Iran
| | - Ghazal MalekMahmoudi
- Department of Neurology, Zanjan University of Medical Sciences, Vali-e-Asr Hospital, Zanjan, Iran
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A PRIMPOL mutation and variants in multiple genes may contribute to phenotypes in a familial case with chronic progressive external ophthalmoplegia symptoms. Neurosci Res 2020; 157:58-63. [DOI: 10.1016/j.neures.2019.07.006] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2019] [Revised: 07/04/2019] [Accepted: 07/22/2019] [Indexed: 11/22/2022]
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Bennuri SC, Rose S, Frye RE. Mitochondrial Dysfunction Is Inducible in Lymphoblastoid Cell Lines From Children With Autism and May Involve the TORC1 Pathway. Front Psychiatry 2019; 10:269. [PMID: 31133888 PMCID: PMC6514096 DOI: 10.3389/fpsyt.2019.00269] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Accepted: 04/09/2019] [Indexed: 01/25/2023] Open
Abstract
We previously developed a lymphoblastoid cell line (LCL) model of mitochondrial dysfunction in autism spectrum disorder (ASD); some individuals with ASD showed mitochondrial dysfunction (AD-A) while other individuals (AD-N) demonstrated mitochondrial respiration similar to controls (CNT). To test the hypothesis that mitochondrial dysfunction could be a consequence of environmental exposures through chronic elevations in reactive oxygen species (ROS), we exposed LCLs to prolonged ROS. We also examined expression of metabolic regulatory genes and the modulating effect of the mechanistic target of rapamycin (mTOR) pathway. Prolonged ROS exposure induced or worsened mitochondrial dysfunction in all LCL groups. Expression of genes associated with ROS protection was elevated in both AD-N and AD-A LCLs, but mitochondrial fission/fusion and mitoplasticity gene expression was only increased in AD-N LCLs. Partial least squares discriminant analysis showed that mTOR, UCP2 (uncoupling protein 2), SIRT1 (sirtuin 1), and MFN2 (mitofusin-2) gene expression differentiated LCL groups. Low-dose rapamycin (0.1 nM) normalized respiration with the magnitude of this normalization greater for AD-A LCLs, suggesting that the mammalian target of rapamycin complex 1 (mTORC1) pathway may have a different dynamic range for regulating mitochondrial activity in individuals with ASD with and without mitochondrial dysfunction, potentially related to S6K1 (S6 kinase beta-1) regulation. Understanding pathways that underlie mitochondrial dysfunction in ASD may lead to novel treatments.
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Affiliation(s)
- Sirish C Bennuri
- Arkansas Children's Research Institute and Department of Pediatrics, University of Arkansas for Medical Sciences, Little Rock, AR, United States
| | - Shannon Rose
- Arkansas Children's Research Institute and Department of Pediatrics, University of Arkansas for Medical Sciences, Little Rock, AR, United States
| | - Richard E Frye
- Barrow Neurologic Institute at Phoenix Children's Hospital, Phoenix, AZ, United States.,Department of Child Health, University of Arizona College of Medicine-Phoenix, Phoenix, AZ, United States
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Edwards AC, Bigdeli TB, Docherty AR, Bacanu S, Lee D, de Candia TR, Moscati A, Thiselton DL, Maher BS, Wormley BK, Walsh D, O’Neill FA, Kendler KS, Riley BP, Fanous AH. Meta-analysis of Positive and Negative Symptoms Reveals Schizophrenia Modifier Genes. Schizophr Bull 2016; 42:279-87. [PMID: 26316594 PMCID: PMC4753595 DOI: 10.1093/schbul/sbv119] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
BACKGROUND Evidence suggests that genetic factors may influence both schizophrenia (Scz) and its clinical presentation. In recent years, genome-wide association studies (GWAS) have demonstrated considerable success in identifying risk loci. Detection of "modifier loci" has the potential to further elucidate underlying disease processes. METHODS We performed GWAS of empirically derived positive and negative symptom scales in Irish cases from multiply affected pedigrees and a larger, independent case-control sample, subsequently combining these into a large Irish meta-analysis. In addition to single-SNP associations, we considered gene-based and pathway analyses to better capture convergent genetic effects, and to facilitate biological interpretation of these findings. Replication and testing of aggregate genetic effects was conducted using an independent European-American sample. RESULTS Though no single marker met the genome-wide significance threshold, genes and ontologies/pathways were significantly associated with negative and positive symptoms; notably, NKAIN2 and NRG1, respectively. We observed limited overlap in ontologies/pathways associated with different symptom profiles, with immune-related categories over-represented for negative symptoms, and addiction-related categories for positive symptoms. Replication analyses suggested that genes associated with clinical presentation are generalizable to non-Irish samples. CONCLUSIONS These findings strongly support the hypothesis that modifier loci contribute to the etiology of distinct Scz symptom profiles. The finding that previously implicated "risk loci" actually influence particular symptom dimensions has the potential to better delineate the roles of these genes in Scz etiology. Furthermore, the over-representation of distinct gene ontologies/pathways across symptom profiles suggests that the clinical heterogeneity of Scz is due in part to complex and diverse genetic factors.
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Affiliation(s)
- Alexis C. Edwards
- Virginia Institute for Psychiatric and Behavioral Genetics, Department of Psychiatry, Virginia Commonwealth University School of Medicine, Richmond, VA;,*To whom correspondence should be addressed; Virginia Institute for Psychiatric and Behavioral Genetics, Department of Psychiatry, Virginia Commonwealth University School of Medicine, PO Box 980126, Richmond, VA 23298-0126, US; tel: 1-804-828-8591, fax: 1-804-828-1471, e-mail:
| | - Tim B. Bigdeli
- Virginia Institute for Psychiatric and Behavioral Genetics, Department of Psychiatry, Virginia Commonwealth University School of Medicine, Richmond, VA
| | - Anna R. Docherty
- Virginia Institute for Psychiatric and Behavioral Genetics, Department of Psychiatry, Virginia Commonwealth University School of Medicine, Richmond, VA
| | - Silviu Bacanu
- Virginia Institute for Psychiatric and Behavioral Genetics, Department of Psychiatry, Virginia Commonwealth University School of Medicine, Richmond, VA
| | - Donghyung Lee
- Virginia Institute for Psychiatric and Behavioral Genetics, Department of Psychiatry, Virginia Commonwealth University School of Medicine, Richmond, VA
| | - Teresa R. de Candia
- Department of Psychology and Neuroscience, University of Colorado, Boulder, CO;,Institute for Behavioral Genetics, University of Colorado, Boulder, CO
| | - Arden Moscati
- Virginia Institute for Psychiatric and Behavioral Genetics, Department of Psychiatry, Virginia Commonwealth University School of Medicine, Richmond, VA
| | - Dawn L. Thiselton
- Virginia Institute for Psychiatric and Behavioral Genetics, Department of Psychiatry, Virginia Commonwealth University School of Medicine, Richmond, VA;,Present address: Health Diagnostic Laboratory, Inc., Richmond, VA
| | - Brion S. Maher
- Department of Mental Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD
| | - Brandon K. Wormley
- Virginia Institute for Psychiatric and Behavioral Genetics, Department of Psychiatry, Virginia Commonwealth University School of Medicine, Richmond, VA
| | | | | | - Francis A. O’Neill
- Centre for Public Health, Institute of Clinical Sciences, Queen’s University Belfast, Belfast, UK
| | - Kenneth S. Kendler
- Virginia Institute for Psychiatric and Behavioral Genetics, Department of Psychiatry, Virginia Commonwealth University School of Medicine, Richmond, VA
| | - Brien P. Riley
- Virginia Institute for Psychiatric and Behavioral Genetics, Department of Psychiatry, Virginia Commonwealth University School of Medicine, Richmond, VA
| | - Ayman H. Fanous
- Virginia Institute for Psychiatric and Behavioral Genetics, Department of Psychiatry, Virginia Commonwealth University School of Medicine, Richmond, VA;,Mental Health Service Line, Washington VA Medical Center, Washington, DC;,Department of Psychiatry, Georgetown University School of Medicine, Washington, DC
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Sequeira A, Rollins B, Magnan C, van Oven M, Baldi P, Myers RM, Barchas JD, Schatzberg AF, Watson SJ, Akil H, Bunney WE, Vawter MP. Mitochondrial mutations in subjects with psychiatric disorders. PLoS One 2015; 10:e0127280. [PMID: 26011537 PMCID: PMC4444211 DOI: 10.1371/journal.pone.0127280] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2014] [Accepted: 04/13/2015] [Indexed: 11/30/2022] Open
Abstract
A considerable body of evidence supports the role of mitochondrial dysfunction in psychiatric disorders and mitochondrial DNA (mtDNA) mutations are known to alter brain energy metabolism, neurotransmission, and cause neurodegenerative disorders. Genetic studies focusing on common nuclear genome variants associated with these disorders have produced genome wide significant results but those studies have not directly studied mtDNA variants. The purpose of this study is to investigate, using next generation sequencing, the involvement of mtDNA variation in bipolar disorder, schizophrenia, major depressive disorder, and methamphetamine use. MtDNA extracted from multiple brain regions and blood were sequenced (121 mtDNA samples with an average of 8,800x coverage) and compared to an electronic database containing 26,850 mtDNA genomes. We confirmed novel and rare variants, and confirmed next generation sequencing error hotspots by traditional sequencing and genotyping methods. We observed a significant increase of non-synonymous mutations found in individuals with schizophrenia. Novel and rare non-synonymous mutations were found in psychiatric cases in mtDNA genes: ND6, ATP6, CYTB, and ND2. We also observed mtDNA heteroplasmy in brain at a locus previously associated with schizophrenia (T16519C). Large differences in heteroplasmy levels across brain regions within subjects suggest that somatic mutations accumulate differentially in brain regions. Finally, multiplasmy, a heteroplasmic measure of repeat length, was observed in brain from selective cases at a higher frequency than controls. These results offer support for increased rates of mtDNA substitutions in schizophrenia shown in our prior results. The variable levels of heteroplasmic/multiplasmic somatic mutations that occur in brain may be indicators of genetic instability in mtDNA.
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Affiliation(s)
- Adolfo Sequeira
- Functional Genomics Laboratory, Department of Psychiatry & Human Behavior, University of California Irvine, Irvine, California, United States of America
| | - Brandi Rollins
- Functional Genomics Laboratory, Department of Psychiatry & Human Behavior, University of California Irvine, Irvine, California, United States of America
| | - Christophe Magnan
- School of Information and Computer Sciences (ICS), Institute for Genomics and Bioinformatics (IGB), University of California Irvine, Irvine, California, United States of America
| | - Mannis van Oven
- Department of Forensic Molecular Biology, Erasmus MC, University Medical Center Rotterdam, Rotterdam, the Netherlands
| | - Pierre Baldi
- School of Information and Computer Sciences (ICS), Institute for Genomics and Bioinformatics (IGB), University of California Irvine, Irvine, California, United States of America
| | - Richard M. Myers
- HudsonAlpha Institute for Biotechnology, Huntsville, Alabama, United States of America
| | - Jack D. Barchas
- Department of Psychiatry, Weill Cornell Medical College, New York, New York, United States of America
| | - Alan F. Schatzberg
- Department of Psychiatry & Behavioral Sciences, Stanford University, Palo Alto, California, United States of America
| | - Stanley J. Watson
- Molecular and Behavioral Neurosciences Institute, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Huda Akil
- Molecular and Behavioral Neurosciences Institute, University of Michigan, Ann Arbor, Michigan, United States of America
| | - William E. Bunney
- Department of Psychiatry & Human Behavior, University of California Irvine, Irvine, California, United States of America
| | - Marquis P. Vawter
- Functional Genomics Laboratory, Department of Psychiatry & Human Behavior, University of California Irvine, Irvine, California, United States of America
- * E-mail:
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Mitochondrial dysfunction in schizophrenia: an evolutionary perspective. Hum Genet 2014; 134:13-21. [PMID: 25312050 DOI: 10.1007/s00439-014-1491-8] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2014] [Accepted: 09/26/2014] [Indexed: 10/24/2022]
Abstract
Schizophrenia (SCZ) is a severe psychiatric illness with a lifetime prevalence of 0.4 %. A disturbance of energy metabolism has been suggested as part of the etiopathogenesis of the disorder. Several lines of evidence have proposed a connection between etiopathogenesis of SCZ and human brain evolution, which was characterized by an increase in the energy requirement, demanding a co-evolution of the mitochondrial system. Mitochondria are key players in brain energy homeostasis and multiple lines of evidence suggest that the system is disrupted in SCZ. In this review, we will describe the current knowledge on pathways/system involved in the human brain evolution as well as the main theories regarding the evolutionary origin of SCZ. We will furthermore discuss the role of mitochondria in the context of brain energy metabolism and its role in the etiopathogenesis of SCZ. Understanding SCZ in the context of human brain evolution opens a new perspective to elucidate pathophysiological mechanisms involved in the origin and/or portions of the complex symptomatology of this severe mental disorder.
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He Y, Tang J, Li Z, Li H, Liao Y, Tang Y, Tan L, Chen J, Xia K, Chen X. Leukocyte mitochondrial DNA copy number in blood is not associated with major depressive disorder in young adults. PLoS One 2014; 9:e96869. [PMID: 24809340 PMCID: PMC4014566 DOI: 10.1371/journal.pone.0096869] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2013] [Accepted: 04/12/2014] [Indexed: 01/02/2023] Open
Abstract
Background Major depressive disorder (MDD) is the leading cause of disability worldwide, and has significant genetic predisposition. Mitochondria may have a role in MDD and so mitochondrial DNA (mtDNA) has been suggested as a possible biomarker for this disease. We aimed to test whether the mtDNA copy number of peripheral blood leukocytes is related to MDD in young adults. Methods A case-control study was conducted with 210 MDD patients and 217 healthy controls (HC). The mtDNA copy number was measured by quantitative polymerase chain reaction (qPCR) method. Depression severity was assessed by the Hamilton-17 Depression Rating Scale (HDRS-17). Results We found no significant differences in mtDNA copy number between MDD patients and HC, though the power analysis showed that our sample size has enough power to detect the difference. There were also no significant correlations between mtDNA copy number and the clinical characteristics (such as age, age of onset, episodes, Hamilton Depression Rating Scale (HDRS) score and Global Assessment of Function Scale (GAF) score) in MDD patients. Conclusion Our study suggests that leukocyte mtDNA copy number is unlikely to contribute to MDD, but it doesn’t mean that we can exclude the possibility of involvement of mitochondria in the disease. Further studies are required to elucidate whether mtDNA can be a biomarker of MDD.
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Affiliation(s)
- Ying He
- Institute of Mental Health, the Second Xiangya Hospital of Central South University, Changsha, Hunan, China
| | - Jinsong Tang
- Institute of Mental Health, the Second Xiangya Hospital of Central South University, Changsha, Hunan, China
| | - Zongchang Li
- Institute of Genomic Medicine, Wenzhou Medical University, Wenzhou, Zhejiang, China
| | - Hong Li
- Institute of Mental Health, the Second Xiangya Hospital of Central South University, Changsha, Hunan, China
| | - Yanhui Liao
- Institute of Mental Health, the Second Xiangya Hospital of Central South University, Changsha, Hunan, China
| | - Yanqing Tang
- Department of Psychiatry, First Affiliated Hospital, China Medical University, Shenyang, Liaoning, China
| | - Liwen Tan
- Institute of Mental Health, the Second Xiangya Hospital of Central South University, Changsha, Hunan, China
| | - Jindong Chen
- Institute of Mental Health, the Second Xiangya Hospital of Central South University, Changsha, Hunan, China
| | - Kun Xia
- The State Key Laboratory of Medical Genetics, Central South University, Changsha, Hunan, China
| | - Xiaogang Chen
- Institute of Mental Health, the Second Xiangya Hospital of Central South University, Changsha, Hunan, China; The State Key Laboratory of Medical Genetics, Central South University, Changsha, Hunan, China; Key Laboratory of Psychiatry and Mental Health of Hunan Province, Central South University, Changsha, Hunan, China; The State Key Laboratory of Medical Genetics, Central South University, Changsha, Hunan, China
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Taylor SD, Ericson NG, Burton JN, Prolla TA, Silber JR, Shendure J, Bielas JH. Targeted enrichment and high-resolution digital profiling of mitochondrial DNA deletions in human brain. Aging Cell 2014; 13:29-38. [PMID: 23911137 PMCID: PMC4068027 DOI: 10.1111/acel.12146] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/21/2013] [Indexed: 12/24/2022] Open
Abstract
Due largely to the inability to accurately quantify and characterize de novo deletion events, the mechanisms underpinning the pathogenic expansion of mtDNA deletions in aging and neuromuscular disorders remain poorly understood. Here, we outline and validate a new tool termed 'Digital Deletion Detection' (3D) that allows for high-resolution analysis of rare deletions occurring at frequencies as low as 1 × 10(-8) . 3D is a three-step process that includes targeted enrichment for deletion-bearing molecules, single-molecule partitioning of genomes into thousands of droplets for direct quantification via droplet digital PCR, and breakpoint characterization using massively parallel sequencing. Using 3D, we interrogated over 8 billion mitochondrial genomes to analyze the age-related dynamics of mtDNA deletions in human brain tissue. We demonstrate that the total deletion load increases with age, while the total number and diversity of unique deletions remain constant. Our data provide support for the hypothesis that expansion of pre-existing mutations is the primary factor contributing to age-related accumulation of mtDNA deletions.
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Affiliation(s)
- Sean D. Taylor
- Translational Research Program; Public Health Sciences Division; Fred Hutchinson Cancer Research Center; 1100 Fairview Ave Seattle WA 98109 USA
| | - Nolan G. Ericson
- Translational Research Program; Public Health Sciences Division; Fred Hutchinson Cancer Research Center; 1100 Fairview Ave Seattle WA 98109 USA
| | - Joshua N. Burton
- Department of Genome Sciences; University of Washington; 3720 15th Ave NE Seattle WA 98195 USA
| | - Tomas A. Prolla
- Department of Medical Genetics; University of Wisconsin-Madison; 425-G Henry Mall Madison WI 53706 USA
| | - John R. Silber
- Neurological Surgery; University of Washington Medical Center; 1959 NE Pacific St Seattle WA 98195 USA
| | - Jay Shendure
- Department of Genome Sciences; University of Washington; 3720 15th Ave NE Seattle WA 98195 USA
| | - Jason H. Bielas
- Translational Research Program; Public Health Sciences Division; Fred Hutchinson Cancer Research Center; 1100 Fairview Ave Seattle WA 98109 USA
- Human Biology Division; Fred Hutchinson Cancer Research Center; 1100 Fairview Ave Seattle WA 98109 USA
- Department of Pathology; University of Washington Medical Center; 1959 NE Pacific St Seattle WA 98195 USA
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Torrell H, Montaña E, Abasolo N, Roig B, Gaviria AM, Vilella E, Martorell L. Mitochondrial DNA (mtDNA) in brain samples from patients with major psychiatric disorders: gene expression profiles, mtDNA content and presence of the mtDNA common deletion. Am J Med Genet B Neuropsychiatr Genet 2013; 162B:213-23. [PMID: 23355257 DOI: 10.1002/ajmg.b.32134] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/08/2012] [Accepted: 01/03/2013] [Indexed: 01/26/2023]
Abstract
Several lines of evidence support a mitochondrial dysfunction in major psychiatric disorders. The objective of this study was to determine whether mitochondrial DNA (mtDNA) expression or content are implicated in the mitochondrial dysfunction observed in schizophrenia (SCH), bipolar disorder (BD), and major depressive disorder (MDD). MtDNA gene expression and mtDNA content (including the MT-ND4 deletion) were measured by RT-qPCR and qPCR, respectively. Post-mortem brain tissue from 60 subjects, divided evenly into four diagnostic groups (SCH, BD, MDD, and control (C)), was analyzed. MT-ND1 gene expression was significantly increased in the BD group compared with the C group. MDD and SCH patients showed a similar pattern of mtDNA expression, which was different from that in BD patients. Similarly, a larger number of MDD and SCH patients tended to have the MT-ND4 gene deleted compared with BD and C subjects. However, no other significant differences were observed in mtDNA gene expression and mtDNA content. Notably, high variability was observed in the mtDNA gene expression and content in each diagnostic group. Previous studies and the present work provide evidence for a role of mtDNA in SCH, BD and MDD. However, further studies with larger patient and control groups as well as by analyzing distinct brain regions are needed to elucidate the role of mtDNA in major psychiatric disorders.
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Affiliation(s)
- Helena Torrell
- Hospital Universitari Psiquiàtric Institut Pere Mata, IISPV, Universitat Rovira i Virgili. C/Sant Llorenç, Reus, Spain
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Malki K, Campbell J, Davies M, Keers R, Uher R, Ward M, Paya-Cano J, Aitchinson KJ, Binder E, Sluyter F, Kuhn K, Selzer S, Craig I, McGuffin P, Schalkwyk LC. Pharmacoproteomic investigation into antidepressant response in two mouse inbred strains. Proteomics 2013; 12:2355-65. [PMID: 22696452 DOI: 10.1002/pmic.201100306] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
In this study, we present a pharmacoproteomic investigation of response to antidepressants two inbred strains. Our aim was to uncover molecular mechanisms underlying antidepressant action and identify new biomarkers to determine therapeutic response to two antidepressants with proven efficacy in the treatment of depression but divergent mechanisms of action. Mice were treated with the pro-noradrenergic drug nortriptyline, the pro-serotonergic drug escitalopram or saline. Quantitative proteomic analyses were undertaken on hippocampal tissue from a study design that used two inbred mouse strains, two depressogenic protocols and a control condition, (maternal separation, chronic mild stress, control), two antidepressant drugs and two dosing protocols. The proteomic analysis was aimed at the identification of specific drug-response markers. Complementary approaches, 2DE and isobaric tandem mass tagging (TMT), were applied to the selected experimental groups. To investigate the relationship between proteomic profiles, depressogenic protocols and drug response, 2DE and TMT data sets were analysed using multivariate methods. The results highlighted significant strain- and stress-related differences across both 2DE and TMT data sets and identified the three gene products involved in serotonergic (PXBD5, YHWAB, SLC25A4) and one in noradrenergic antidepressant action (PXBD6).
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Affiliation(s)
- Karim Malki
- King's College London, MRC Social, Genetic and Developmental Psychiatry Centre, Institute of Psychiatry, London, UK.
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Schreiber H. Pilot study on executive function and adaptive skills in adolescents and young adults with mitochondrial disease. J Child Neurol 2012; 27:1506-16. [PMID: 22628220 DOI: 10.1177/0883073812442589] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
High-functioning adolescents and young adults with mitochondrial disease are now attempting transitions to postsecondary environments. This pilot and case study explores factors that interfere with their successful transition through behavior-rating scales addressing academic skills and behavior. In the Behavior Assessment System for Children, Second Edition, Spearman correlation matrices showed that students' attitude to school was associated with depression and anxiety. Mothers' reports linked internalizing disorders with somatic symptoms. Two case studies, with Behavior Rating Inventory of Executive Function profiles, show the role executive functions play in academic success. Attention to both cognitive and psychiatric concerns may increase success in academics and enhance the sense of well-being in older students with mitochondrial disease.
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Affiliation(s)
- Hope Schreiber
- Department of Psychiatry, Tufts Medical Center, Tufts University School of Medicine, Boston, MA 02111, USA.
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Abstract
AbstractThe science of genetics is undergoing a paradigm shift. Recent discoveries, including the activity of retrotransposons, the extent of copy number variations, somatic and chromosomal mosaicism, and the nature of the epigenome as a regulator of DNA expressivity, are challenging a series of dogmas concerning the nature of the genome and the relationship between genotype and phenotype. According to three widely held dogmas, DNA is the unchanging template of heredity, is identical in all the cells and tissues of the body, and is the sole agent of inheritance. Rather than being an unchanging template, DNA appears subject to a good deal of environmentally induced change. Instead of identical DNA in all the cells of the body, somatic mosaicism appears to be the normal human condition. And DNA can no longer be considered the sole agent of inheritance. We now know that the epigenome, which regulates gene expressivity, can be inherited via the germline. These developments are particularly significant for behavior genetics for at least three reasons: First, epigenetic regulation, DNA variability, and somatic mosaicism appear to be particularly prevalent in the human brain and probably are involved in much of human behavior; second, they have important implications for the validity of heritability and gene association studies, the methodologies that largely define the discipline of behavior genetics; and third, they appear to play a critical role in development during the perinatal period and, in particular, in enabling phenotypic plasticity in offspring. I examine one of the central claims to emerge from the use of heritability studies in the behavioral sciences, the principle of minimal shared maternal effects, in light of the growing awareness that the maternal perinatal environment is a critical venue for the exercise of adaptive phenotypic plasticity. This consideration has important implications for both developmental and evolutionary biology.
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Sangatsuda Y, Nakamura M, Tomiyasu A, Deguchi A, Toyota Y, Goto YI, Nishino I, Ueno SI, Sano A. Heteroplasmic m.1624C>T mutation of the mitochondrial tRNA(Val) gene in a proband and his mother with repeated consciousness disturbances. Mitochondrion 2012; 12:617-22. [PMID: 23063709 DOI: 10.1016/j.mito.2012.10.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2012] [Revised: 09/03/2012] [Accepted: 10/02/2012] [Indexed: 10/27/2022]
Abstract
Homoplasmic m.1624C>T mutation of the mitochondrial tRNA(Val) gene was previously demonstrated to cause fatal neonatal Leigh syndrome. Here, we report the clinical phenotypes of a Japanese male and his mother with heteroplasmic m.1624C>T mutation. The 36-year-old male presented with repeated episodes of consciousness disturbance since the age of 25, cognitive decline, and personality change. Cerebrospinal fluid levels of lactate and pyruvate were elevated. His mother showed similar symptoms and course. The mutation m.1624C>T was identified heteroplasmically in the proband's muscle and leukocytes and in the mother's leukocytes. The heteroplasmy load decreased with age.
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Affiliation(s)
- Yoko Sangatsuda
- Department of Psychiatry, Kagoshima University Graduate School of Medical and Dental Sciences, 8-35-1 Sakuragaoka, Kagoshima 890-8520, Japan.
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16
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Diagnosis of mitochondrial disorders applying massive pyrosequencing. Mol Biol Rep 2012; 39:6655-60. [PMID: 22302390 DOI: 10.1007/s11033-012-1471-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2012] [Accepted: 01/23/2012] [Indexed: 10/14/2022]
Abstract
Mitochondrial disorders are a frequent cause of neurological disability affecting children and adults. Traditionally, molecular diagnosis of mitochondrial diseases was mostly accomplished by the use of Sanger sequencing and PCR-RFLP. However, there are particular drawbacks associated with the use of these methods. Recent multidisciplinary advances have led to new sequencing methods that may overcome these limitations. Our goal was to explore the use of a next generation sequencing platform in the molecular diagnosis of mitochondrial diseases reporting our findings in adult patients that present with a clinical-pathological diagnosis of a mitochondrial encephalomyopathy. Complete genomic sequences of mitochondrial DNA were obtained by 454 massive pyrosequencing from blood samples. The analysis of these sequences allowed us to identify two diagnostic pathogenic mutations and 74 homoplasmic polymorphisms, useful for obtaining high-resolution mitochondrial haplogroups. In summary, molecular diagnosis of mitochondrial disorders could be efficiently done from readily accessible samples, such as blood, with the use of a new sequencing platform.
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Pitceathly R, Rahman S, Hanna M. Single deletions in mitochondrial DNA – Molecular mechanisms and disease phenotypes in clinical practice. Neuromuscul Disord 2012; 22:577-86. [DOI: 10.1016/j.nmd.2012.03.009] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2011] [Revised: 02/26/2012] [Accepted: 03/21/2012] [Indexed: 12/20/2022]
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Sequeira A, Martin MV, Rollins B, Moon EA, Bunney WE, Macciardi F, Lupoli S, Smith EN, Kelsoe J, Magnan CN, van Oven M, Baldi P, Wallace DC, Vawter MP. Mitochondrial mutations and polymorphisms in psychiatric disorders. Front Genet 2012; 3:103. [PMID: 22723804 PMCID: PMC3379031 DOI: 10.3389/fgene.2012.00103] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2012] [Accepted: 05/20/2012] [Indexed: 12/31/2022] Open
Abstract
Mitochondrial deficiencies with unknown causes have been observed in schizophrenia (SZ) and bipolar disorder (BD) in imaging and postmortem studies. Polymorphisms and somatic mutations in mitochondrial DNA (mtDNA) were investigated as potential causes with next generation sequencing of mtDNA (mtDNA-Seq) and genotyping arrays in subjects with SZ, BD, major depressive disorder (MDD), and controls. The common deletion of 4,977 bp in mtDNA was compared between SZ and controls in 11 different vulnerable brain regions and in blood samples, and in dorsolateral prefrontal cortex (DLPFC) of BD, SZ, and controls. In a separate analysis, association of mitochondria SNPs (mtSNPs) with SZ and BD in European ancestry individuals (n = 6,040) was tested using Genetic Association Information Network (GAIN) and Wellcome Trust Case Control Consortium 2 (WTCCC2) datasets. The common deletion levels were highly variable across brain regions, with a 40-fold increase in some regions (nucleus accumbens, caudate nucleus and amygdala), increased with age, and showed little change in blood samples from the same subjects. The common deletion levels were increased in the DLPFC for BD compared to controls, but not in SZ. Full mtDNA genome resequencing of 23 subjects, showed seven novel homoplasmic mutations, five were novel synonymous coding mutations. By logistic regression analysis there were no significant mtSNPs associated with BD or SZ after genome wide correction. However, nominal association of mtSNPs (p < 0.05) to SZ and BD were found in the hypervariable region of mtDNA to T195C and T16519C. The results confirm prior reports that certain brain regions accumulate somatic mutations at higher levels than blood. The study in mtDNA of common polymorphisms, somatic mutations, and rare mutations in larger populations may lead to a better understanding of the pathophysiology of psychiatric disorders.
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Affiliation(s)
- Adolfo Sequeira
- Functional Genomics Laboratory, Department of Psychiatry and Human Behavior, University of CaliforniaIrvine, CA, USA
| | - Maureen V. Martin
- Functional Genomics Laboratory, Department of Psychiatry and Human Behavior, University of CaliforniaIrvine, CA, USA
| | - Brandi Rollins
- Functional Genomics Laboratory, Department of Psychiatry and Human Behavior, University of CaliforniaIrvine, CA, USA
| | - Emily A. Moon
- Functional Genomics Laboratory, Department of Psychiatry and Human Behavior, University of CaliforniaIrvine, CA, USA
| | - William E. Bunney
- Department of Psychiatry and Human Behavior, University of CaliforniaIrvine, CA, USA
| | - Fabio Macciardi
- Department of Psychiatry and Human Behavior, University of CaliforniaIrvine, CA, USA
- Department of Medicine, Surgery and Dentistry, University of MilanMilan, Italy
| | - Sara Lupoli
- Department of Medicine, Surgery and Dentistry, University of MilanMilan, Italy
| | - Erin N. Smith
- Department of Pediatrics, School of Medicine, Rady’s Children’s Hospital, University of CaliforniaSan Diego, CA, USA
| | - John Kelsoe
- Psychiatry Service, Veterans Affairs San Diego Healthcare SystemSan Diego, CA, USA
- Department of Psychiatry, University of CaliforniaSan Diego, CA, USA
| | - Christophe N. Magnan
- School of Information and Computer Sciences, Institute for Genomics and Bioinformatics, University of California IrvineIrvine, CA, USA
| | - Mannis van Oven
- Department of Forensic Molecular Biology, Erasmus MC University Medical CenterRotterdam, Netherlands
| | - Pierre Baldi
- School of Information and Computer Sciences, Institute for Genomics and Bioinformatics, University of California IrvineIrvine, CA, USA
| | - Douglas C. Wallace
- Department of Pathology and Laboratory Medicine, University of PennsylvaniaPhiladelphia, PA, USA
| | - Marquis P. Vawter
- Functional Genomics Laboratory, Department of Psychiatry and Human Behavior, University of CaliforniaIrvine, CA, USA
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Rossignol DA, Frye RE. A review of research trends in physiological abnormalities in autism spectrum disorders: immune dysregulation, inflammation, oxidative stress, mitochondrial dysfunction and environmental toxicant exposures. Mol Psychiatry 2012; 17:389-401. [PMID: 22143005 PMCID: PMC3317062 DOI: 10.1038/mp.2011.165] [Citation(s) in RCA: 359] [Impact Index Per Article: 29.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Recent studies have implicated physiological and metabolic abnormalities in autism spectrum disorders (ASD) and other psychiatric disorders, particularly immune dysregulation or inflammation, oxidative stress, mitochondrial dysfunction and environmental toxicant exposures ('four major areas'). The aim of this study was to determine trends in the literature on these topics with respect to ASD. A comprehensive literature search from 1971 to 2010 was performed in these four major areas in ASD with three objectives. First, publications were divided by several criteria, including whether or not they implicated an association between the physiological abnormality and ASD. A large percentage of publications implicated an association between ASD and immune dysregulation/inflammation (416 out of 437 publications, 95%), oxidative stress (all 115), mitochondrial dysfunction (145 of 153, 95%) and toxicant exposures (170 of 190, 89%). Second, the strength of evidence for publications in each area was computed using a validated scale. The strongest evidence was for immune dysregulation/inflammation and oxidative stress, followed by toxicant exposures and mitochondrial dysfunction. In all areas, at least 45% of the publications were rated as providing strong evidence for an association between the physiological abnormalities and ASD. Third, the time trends in the four major areas were compared with trends in neuroimaging, neuropathology, theory of mind and genetics ('four comparison areas'). The number of publications per 5-year block in all eight areas was calculated in order to identify significant changes in trends. Prior to 1986, only 12 publications were identified in the four major areas and 51 in the four comparison areas (42 for genetics). For each 5-year period, the total number of publications in the eight combined areas increased progressively. Most publications (552 of 895, 62%) in the four major areas were published in the last 5 years (2006-2010). Evaluation of trends between the four major areas and the four comparison areas demonstrated that the largest relative growth was in immune dysregulation/inflammation, oxidative stress, toxicant exposures, genetics and neuroimaging. Research on mitochondrial dysfunction started growing in the last 5 years. Theory of mind and neuropathology research has declined in recent years. Although most publications implicated an association between the four major areas and ASD, publication bias may have led to an overestimation of this association. Further research into these physiological areas may provide insight into general or subset-specific processes that could contribute to the development of ASD and other psychiatric disorders.
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Affiliation(s)
- D A Rossignol
- International Child Development Resource Center, Melbourne, FL 32934, USA.
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Kennedy SR, Loeb LA, Herr AJ. Somatic mutations in aging, cancer and neurodegeneration. Mech Ageing Dev 2012; 133:118-26. [PMID: 22079405 PMCID: PMC3325357 DOI: 10.1016/j.mad.2011.10.009] [Citation(s) in RCA: 124] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2011] [Revised: 10/05/2011] [Accepted: 10/22/2011] [Indexed: 10/15/2022]
Abstract
The somatic mutation theory of aging posits that the accumulation of mutations in the genetic material of somatic cells as a function of time results in a decrease in cellular function. In particular, the accumulation of random mutations may inactivate genes that are important for the functioning of the somatic cells of various organ systems of the adult, result in a decrease in organ function. When the organ function decreases below a critical level, death occurs. A significant amount of research has shown that somatic mutations play an important role in aging and a number of age related pathologies. In this review, we explore evidence for increases in somatic nuclear mutation burden with age and the consequences for aging, cancer, and neurodegeneration. We then review evidence for increases in mitochondrial mutation burden and the consequences for dysfunction in the disease processes.
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Affiliation(s)
- Scott R. Kennedy
- Department of Pathology, University of Washington School of Medicine, Seattle, Washington, 98195-7705
| | - Lawrence A. Loeb
- Department of Pathology, University of Washington School of Medicine, Seattle, Washington, 98195-7705
- Department of Biochemistry, University of Washington School of Medicine, Seattle, Washington, 98195-7705
| | - Alan J. Herr
- Department of Pathology, University of Washington School of Medicine, Seattle, Washington, 98195-7705
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Takata A, Kato M, Nakamura M, Yoshikawa T, Kanba S, Sano A, Kato T. Exome sequencing identifies a novel missense variant in RRM2B associated with autosomal recessive progressive external ophthalmoplegia. Genome Biol 2011; 12:R92. [PMID: 21951382 PMCID: PMC3308055 DOI: 10.1186/gb-2011-12-9-r92] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2011] [Revised: 06/28/2011] [Accepted: 09/28/2011] [Indexed: 01/21/2023] Open
Abstract
BACKGROUND Whole-exome sequencing using next-generation technologies has been previously demonstrated to be able to detect rare disease-causing variants. Progressive external ophthalmoplegia (PEO) is an inherited mitochondrial disease that follows either autosomal dominant or recessive forms of inheritance (adPEO or arPEO). AdPEO is a genetically heterogeneous disease and several genes, including POLG1 and C10orf2/Twinkle, have been identified as responsible genes. On the other hand, POLG1 was the only established gene causing arPEO with mitochondrial DNA deletions. We previously reported a case of PEO with unidentified genetic etiology. The patient was born of a first-cousin marriage. Therefore, the recessive form of inheritance was suspected. RESULTS To identify the disease-causing variant in this patient, we subjected the patient's DNA to whole-exome sequencing and narrowed down the candidate variants using public data and runs of homozygosity analysis. A total of 35 novel, putatively functional variants were detected in the homozygous segments. When we sorted these variants by the conservation score, a novel missense variant in RRM2B, whose heterozygous rare variant had been known to cause adPEO, was ranked at the top. The list of novel, putatively functional variants did not contain any other variant in genes encoding mitochondrial proteins registered in MitoCarta. CONCLUSIONS Exome sequencing efficiently and effectively identified a novel, homozygous missense variant in RRM2B, which was strongly suggested to be causative for arPEO. The findings in this study indicate arPEO to be a genetically heterogeneous disorder, as is the case for adPEO.
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Affiliation(s)
- Atsushi Takata
- Laboratory for Molecular Dynamics of Mental Disorders, RIKEN Brain Science Institute, 2-1 Hirosawa, Wako-shi, Saitama 351-0198, Japan
- Department of Neuropsychiatry, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan
- Laboratory for Molecular Psychiatry, RIKEN Brain Science Institute, 2-1 Hirosawa, Wako-shi, Saitama 351-0198, Japan
| | - Maiko Kato
- Department of Psychiatry, Kagoshima University Graduate School of Medical and Dental Sciences, 8-35-1 Sakuragaoka, Kagoshima-shi, Kagoshima 890-8520, Japan
| | - Masayuki Nakamura
- Department of Psychiatry, Kagoshima University Graduate School of Medical and Dental Sciences, 8-35-1 Sakuragaoka, Kagoshima-shi, Kagoshima 890-8520, Japan
| | - Takeo Yoshikawa
- Laboratory for Molecular Psychiatry, RIKEN Brain Science Institute, 2-1 Hirosawa, Wako-shi, Saitama 351-0198, Japan
| | - Shigenobu Kanba
- Department of Neuropsychiatry, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan
| | - Akira Sano
- Department of Psychiatry, Kagoshima University Graduate School of Medical and Dental Sciences, 8-35-1 Sakuragaoka, Kagoshima-shi, Kagoshima 890-8520, Japan
| | - Tadafumi Kato
- Laboratory for Molecular Dynamics of Mental Disorders, RIKEN Brain Science Institute, 2-1 Hirosawa, Wako-shi, Saitama 351-0198, Japan
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