The DOI matches its Crossref record; 30 of the 30 references it cites were found in a registry or an index.
Functional consequences of a CKIδ mutation causing familial advanced sleep phase syndrome
Abstract
Familial advanced sleep phase syndrome (FASPS) is a human behavioural phenotype characterized by early sleep times and early-morning awakening. It was the first human, mendelian circadian rhythm variant to be well-characterized, and was shown to result from a mutation in a phosphorylation site within the casein kinase I (CKI)-binding domain of the human PER2 gene. To gain a deeper understanding of the mechanisms of circadian rhythm regulation in humans, we set out to identify mutations in human subjects leading to FASPS. We report here the identification of a missense mutation (T44A) in the human CKIdelta gene, which results in FASPS. This mutant kinase has decreased enzymatic activity in vitro. Transgenic Drosophila carrying the human CKIdelta-T44A gene showed a phenotype with lengthened circadian period. In contrast, transgenic mice carrying the same mutation have a shorter circadian period, a phenotype mimicking human FASPS. These results show that CKIdelta is a central component in the mammalian clock, and suggest that mammalian and fly clocks might have different regulatory mechanisms despite the highly conserved nature of their individual components.
Overview
Integrity signals
Registry
Cites
Statistics
Verification
Claims the paper makes
Claims other papers make about this one
Each is checked against this paper’s own text: does it say what the citing paper says it does?
In the citing paper
“Herein, specific mutations in circadian clock regulators that affect human circadian behavior and the period of the underlying clock have been identified (38, 39).”
From Chronotype: Implications for Epidemiologic Studies on Chrono-Nutrition and Cardiometabolic Health (2019) · cites this paper as [39]
Citations
Cites
Molecular Bases for Circadian Clocks
Dunlap, J. C. (1999) · Cell · doi:10.1016/s0092-8674(00)80566-8 · Cited by 2,900
Mutagenesis and Mapping of a Mouse Gene, Clock , Essential for Circadian Behavior
Vitaterna, M. H., King, D. P., Chang, A.-M., Kornhauser, J. M., Lowrey, P. L., McDonald, J. D., Dove, W. F., Pinto, L. H., Turek, F. W., & Takahashi, J. S. (1994) · Science · doi:10.1126/science.8171325 · Cited by 1,632
An h Per2 Phosphorylation Site Mutation in Familial Advanced Sleep Phase Syndrome
Toh, K. L., Jones, C. R., He, Y., Eide, E. J., Hinz, W. A., Virshup, D. M., Ptáček, L. J., & Fu, Y.-H. (2001) · Science · doi:10.1126/science.1057499 · Cited by 1,460
Self-citationInteracting molecular loops in the mammalian circadian clock
Shearman, L. P., Sriram, S., Weaver, D. R., Maywood, E. S., Chaves, I., Zheng, B., Kume, K., Lee, C. C., van der, G. T. J., Horst, et al. (2000) · Science · doi:10.1126/science.288.5468.1013 · Cited by 1,367
Posttranslational Mechanisms Regulate the Mammalian Circadian Clock
Lee, C., Etchegaray, J., Cagampang, F. R. A., Loudon, A. S. I., & Reppert, S. M. (2001) · Cell · doi:10.1016/s0092-8674(01)00610-9 · Cited by 1,174
Positional Syntenic Cloning and Functional Characterization of the Mammalian Circadian Mutation tau
Lowrey, P. L., Shimomura, K., Antoch, M. P., Yamazaki, S., Zemenides, P. D., Ralph, M. R., Menaker, M., & Takahashi, J. S. (2000) · Science · doi:10.1126/science.288.5465.483 · Cited by 860
double-time Is a Novel Drosophila Clock Gene that Regulates PERIOD Protein Accumulation
Price, J. L., Blau, J., Rothenfluh, A., Abodeely, M., Kloss, B., & Young, M. W. (1998) · Cell · doi:10.1016/s0092-8674(00)81224-6 · Cited by 839
Beck, A. T., Ward, C. H., Mendelson, M., Mock, J., & Erbauch, J. (1961) · PsycTESTS Dataset · doi:10.1037/t00741-000 · Cited by 816
A Mutation of the Circadian System in Golden Hamsters
Ralph, M. R., & Menaker, M. (1988) · Science · doi:10.1126/science.3413487 · Cited by 697
The Drosophila Clock Gene double-time Encodes a Protein Closely Related to Human Casein Kinase Iε
Kloss, B., Price, J. L., Sáez, L., Blau, J., Rothenfluh, A., Wesley, C. S., & Young, M. W. (1998) · Cell · doi:10.1016/s0092-8674(00)81225-8 · Cited by 682
Cited by
Sorted by citations
Items 701–800 of 861
Sleepless Patient: Circadian Rhythm Sleep–Wake Disorders
Kendis, H., & Zee, P. C. (2015) · Springer eBooks · doi:10.1007/978-3-319-18054-0_11 · Cited by 1
The roles of vasoactive intestinal polypeptide in circadian entrainment of suprachiasmatic nucleus
An, S. (2011) · Open Scholarship Institutional Repository (Washington University in St. Louis) · doi:10.7936/k7ff3qch · Cited by 1
Duncan, W. C. (2009) · Birkhäuser Basel eBooks · doi:10.1007/978-3-7643-8567-5_7 · Cited by 1
Generalprinciples of genetics and genomics
Shaw, P. J., Tafti, M., & Thorpy, M. J. (2013) · Cambridge University Press eBooks · doi:10.1017/cbo9781139649469.003 · Cited by 1
Psychological Approaches to Headache
Seng, E. K., & Baskin, S. M. (2015) · Elsevier eBooks · doi:10.1016/b978-0-12-800901-7.00019-7 · Cited by 1
Circadian rhythm sleep disorders
Chervin, R. D. (2014) · Cambridge University Press eBooks · doi:10.1017/cbo9781139583848.083 · Cited by 1
Genetics and Genomic Basis of Sleep in Simple Model Organisms
Allada, R., & Wu, M. N. (2016) · Elsevier eBooks · doi:10.1016/b978-0-323-24288-2.00028-3 · Cited by 1
Insights from studying human sleep
Mahowald, W., & Schenck, C. H. (2005) · Cited by 1
Tanizawa, K., & Chin, K. (2018) · Respiratory disease series · doi:10.1007/978-981-10-8144-6_13 · Cited by 1
Genetics of Normal Human Sleep
Hor, H., & Tafti, M. (2016) · Elsevier eBooks · doi:10.1016/b978-0-323-24288-2.00006-4 · Cited by 1
Características generales del sueño normal
Chokroverty, S. (2011) · Elsevier eBooks · doi:10.1016/b978-84-8086-733-7.00002-4 · Cited by 1
Human and Animal Genetics of Sleep and Sleep Disorders
Maret, S., Dauvilliers, Y. A., & Tafti, M. (2009) · Elsevier eBooks · doi:10.1016/b978-0-7506-7584-0.00022-7 · Cited by 1
The Assessment of Sleep Disorders in Dually Diagnosed Individuals
Wagner, J. H., Mcpherson, P., Pistorius, R., Shukla, A., & Parvataneni, S. (2020) · Autism and child psychopathology series · doi:10.1007/978-3-030-46835-4_23
Kim, W. D., Yap, S. Q., & Huber, R. J. (2021) · International Journal of Molecular Sciences · doi:10.3390/ijms22041722 · Cited by 1
A Small Molecule Modulates Circadian Rhythms through Phosphorylation of the Period Protein
Lee, J. W., Hirota, T., Peters, E. C., Garcia, M. E., Gonzalez, R., Cho, C. Y., Wu, X., Schultz, P. G., & Kay, S. A. (2011) · Angewandte Chemie · doi:10.1002/ange.201103915 · Cited by 1
Persico, A. M., Lamberti, M., & Farkas, V. (2017) · Headache · doi:10.1007/978-3-319-54726-8_3 · Cited by 1
Human primary cells can tell body time: Dedicated to Steven A. Brown
Katsioudi, G., Biancolin, A. D., Jiménez‐Sánchez, C., & Dibner, C. (2024) · European Journal of Neuroscience · doi:10.1111/ejn.16453 · Cited by 1
Mechanisms of Circadian Oscillations
Rizvi, S. I., & Majumdar, G. (2024) · Springer eBooks · doi:10.1007/978-981-97-6695-6_2 · Cited by 1
Genetic approaches to understanding circadian entrainment
Roenneberg, T., & Allebrandt, K. V. (2013) · Cambridge University Press eBooks · doi:10.1017/cbo9781139649469.018 · Cited by 1
Melatonin and the “Diseases of the Soul”: The Stone of Madness Returns
Cardinali, D. P. (2016) · Springer eBooks · doi:10.1007/978-3-319-41679-3_10 · Cited by 1
The Genetic Regulation of Human Sleep-Wake Rhythms and Patterns
Kurien, P. A., Ptáček, L. J., & Fu, Y. (2019) · Handbook of behavioral neuroscience · doi:10.1016/b978-0-12-813743-7.00011-6 · Cited by 1
Self-citationEtiopathogenesis of Circadian Sleep–Wake Rhythm Disorders
Domaç, F. M. (2020) · Elsevier eBooks · doi:10.1016/b978-0-12-816658-1.00009-0 · Cited by 1
Genetics of Sleep and Sleep Disorders
Maret, S., Dauvilliers, Y. A., & Tafti, M. (2017) · Springer eBooks · doi:10.1007/978-1-4939-6578-6_29 · Cited by 1
Graw, J. (2020) · Springer eBooks · doi:10.1007/978-3-662-60909-5_14 · Cited by 1
Circadian Rhythm Sleep–Wake Disorders: Mechanisms and Treatment
Abbott, S. M., & Zee, P. C. (2022) · Translational medicine research · doi:10.1007/978-94-024-2168-2_13 · Cited by 1
Next-Generation Mice Genetics for Circadian Studies
Ukai, H., Ode, K. L., & Ueda, H. R. (2022) · Neuromethods · doi:10.1007/978-1-0716-2577-4_17 · Cited by 1
The Circadian Clock: Physiology, Genes, and Disease
Antle, M. C. (2008) · Humana Press eBooks · doi:10.1007/978-1-59745-374-5_22 · Cited by 1
Mistlberger, R. E. (2015) · Wiley eBooks · doi:10.1002/9781118467831.ch4 · Cited by 1
From genes to neurons to brain
Geschwind, D. H. (2006) · Genes Brain & Behavior · doi:10.1111/j.1601-183x.2006.00222.x · Cited by 1
Disease models and mechanisms in the classroom
Gitler, A. D. (2009) · Disease Models & Mechanisms · doi:10.1242/dmm.002600 · Cited by 1
Wilkins, A. K. (2008) · DSpace@MIT (Massachusetts Institute of Technology) · Cited by 1
Lifestyle and environmental risk factors for infertility
Su, H.-C. I., & Barnhart, K. T. (2006) · Expert Review of Obstetrics & Gynecology · doi:10.1586/17474108.1.2.215 · Cited by 1
Optimal portfolio selection for cash-flows with bounded capital at risk
Vyncke, D., Goovaerts, M. J., Dhaene, J., & Vanduffel, S. (2005) · RePEc: Research Papers in Economics · Cited by 1
Genetic Variation in Neurotransmitter Receptors Generates Behavioral Diversity
Bendesky, A. (2025) · Digital Commons - RU (Rockefeller University) · doi:10.48496/3y0n-tx90 · Cited by 1
How to Measure Circadian Rhythmicity in Humans
Hofstra, W. A., & de Weerd, A. (2011) · Epilepsy · doi:10.1201/b10866-45 · Cited by 1
Types of Circadian Rhythm Sleep Disorders
Burgess, H. J., & Reid, K. J. (2008) · CRC Press eBooks · doi:10.3109/9781420019926-14 · Cited by 1
Are all types of migraine channelopathies?
(2020) · doi:10.5348/n06-2015-6-ed-5 · Cited by 1
Delaunay, F. (2009) · Wiley eBooks · doi:10.1002/9780470498392.ch2 · Cited by 1
Ashbrook, L. H., & Ptáček, L. J. (2022) · Elsevier eBooks · doi:10.1016/b978-0-12-822963-7.00309-1 · Cited by 1
Self-citationCircadian rhythm sleep disorder: genetic and environmental factors
Chellappa, S. L., Viola, A., & Mongrain, V. (2013) · Elsevier eBooks · doi:10.1016/b978-0-12-822963-7.60002-6 · Cited by 1
Myopia and hyperopia are associated with opposite chronotypes in a sample of 71,016 individualsPreprint
Palumaa, T., Taba, N., Teder‐Laving, M., Kivi, K.-L., Reis, K., Võsa, U., Esko, T., & Abner, E. (2024) · medRxiv · doi:10.1101/2024.02.13.24302718 · Cited by 3
Comprehensive Mapping of PERIOD2 Expression Patterns in the Rat Forebrain Across the 24-hr Day
Harbour, V. L. (2011) · Spectrum Research Repository (Concordia University) · Cited by 1
Graw, J. (2015) · Springer eBooks · doi:10.1007/978-3-662-44817-5_14
Shaw, P. J., Tafti, M., & Thorpy, M. J. (2013) · Cambridge University Press eBooks · doi:10.1017/cbo9781139649469.037
Molecular and Genetic Bases for the Circadian System
Ko, C. H., & Takahashi, J. S. (2013) · Elsevier eBooks · doi:10.1016/b978-0-12-378610-4.00090-5
Clocks, Brain Function, and Dysfunction
Feillet, C. A., & Albrecht, U. (2009) · Springer eBooks · doi:10.1007/978-1-4419-1262-6_10
Gehrman, P., & Raizen, D. M. (2013) · Elsevier eBooks · doi:10.1016/b978-0-12-378610-4.00171-6
Molecular Determinants of Human Circadian Clocks
Brown, S. A. (2015) · Wiley eBooks · doi:10.1002/9781118467831.ch2
CIRCADIAN AND HOMEOSTATIC REGULATION OF SLEEP IN CAST/EiJ AND C57BL/6J MICE
Jiang, P. (2011) · UKnowledge (University of Kentucky)
Genetics of Circadian Disorders in Humans
Chang, A., & Zee, P. C. (2009) · Elsevier eBooks · doi:10.1016/b978-008045046-9.01617-x
Genome-wide association study (GWAS) approaches to sleep phenotypes
Abou‐Sleiman, P. M., March, M., & Hakonarson, H. H. (2013) · Cambridge University Press eBooks · doi:10.1017/cbo9781139649469.005
The human circadian timing system in aging, alzheimer's disease and depression
Wu, Y. (2007) · UvA-DARE (University of Amsterdam)
INVESTIGATIONS OF CIRCADIAN REGULATION AND IMMUNE-CIRCADIAN INTERACTION IN THE HORSE
Murphy, B. A. (2007) · UKnowledge (University of Kentucky)
Circadian Rhythm Sleep Disorder: Genetic and Environmental Factors
Chellappa, S. L., Viola, A., & Mongrain, V. (2013) · Elsevier eBooks · doi:10.1016/b978-0-12-378610-4.00263-1
Sleepphysiology and homeostasis
Shaw, P. J., Tafti, M., & Thorpy, M. J. (2013) · Cambridge University Press eBooks · doi:10.1017/cbo9781139649469.016
Insomnia and Circadian Rhythm Sleep Disorders
Zee, P. C., & Lu, B. S. (2008) · Psychiatric Annals · doi:10.3928/00485713-20080901-11
Genetic pathways of Lyst and exfoliation syndrome
Trantow, C. M., Anderson, M. G., Cornell, R. A., Piper, R. C., Davidson, B. L., Johnson, W. A., & Russo, A. F. (2009) · doi:10.17077/etd.hhbg0jn6
Ultra-High Throughput Screening (uHTS) Chemical Genetics to Identify Novel Chronotherapeutics
Kay, S. A., & Hirota, T. (2009) · Springer eBooks · doi:10.1007/978-4-431-98074-2_18
CLUES SEEN TO GENETICS OF ADVANCED SLEEP-PHASE SYNDROME
Moyer, P. (2005) · Neurology Today · doi:10.1097/00132985-200507000-00011
Epigenetic Control of Circadian Clock Operation during Development
Li, C., Gong, C., Yu, S., Wu, J., & Li, X. (2012) · Genetics Research International · doi:10.1155/2012/845429
Circadian Rhythms in Health and Disease
Khoury, J. S., & Doghramji, K. (2014) · FOCUS The Journal of Lifelong Learning in Psychiatry · doi:10.1176/appi.focus.12.1.45
A cellular model for human daily behaviour
Pagani, L. (2010) · edoc (University of Basel) · doi:10.5451/unibas-005398037
Behavioral, Neurobiological, and Genetic Analysis of the Circadian Mutant Duper
Manoogian, E. N. C. (2015) · ScholarWorks@UMassAmherst (University of Massachusetts Amherst) · doi:10.7275/7525276.0
The role of circadian clock genes in mental
Coutu, D. L., & Boivin, D. B. (2007)
Aspectos genéticos do sono em humanos
Guindalini, C., & Tufik, S. B. (2012) · Sleep Science
Organisation tissulaire de l'horloge circadienne dans la rétine de rongeur
Jaeger, C. (2014) · theses.fr (ABES) · doi:10.70675/bc3c3121ze047z42e7za694z92b6abbf1cc8
KaiC CII Ring Flexibility Governs the Rhythm of the Circadian Clock of Cyanobacteria
Kuo, N.-W. (2011) · OakTrust (Texas A&M University Libraries)
Goldstein, C. A. (2014) · Cambridge University Press eBooks · doi:10.1017/cbo9781139583848.051
Protein Modifications Pace the Circadian Oscillation of Biological Clocks
Yoshitane, H., & Fukada, Y. (2015) · Springer eBooks · doi:10.1007/978-4-431-55561-2_16
Protein Phosphatase 4 ist ein neuer Regulator der circadianen Uhr in Säugern
Mathematisch-naturwissenschaftlichen Fakultät, I. (2014)
3 Genes, Environments, and Concepts of Biological Inheritance
Mameli, M. (2008) · Oxford University Press eBooks · doi:10.1093/acprof:oso/9780195332834.003.0003
Genetic Research on Sleep, Sleep Disturbances and Associated Difficulties
Gregory, A. M., Parsons, M. J., Barclay, N. L., Gehrman, P., & O’Leary, R. (2016) · Palgrave Macmillan UK eBooks · doi:10.1057/9781137437327_10
The Per2 Negative Feedback Loop Sets the Period in the Mammalian Circadian Clock
Wilkins, M. K., Barton, P. I., & Tidor, B. (2007)
Approach to the patient who cannot sleep
(2004) · CRC Press eBooks · doi:10.3109/9780203492055-15
Sirkadiyen Ritim Uyku Bozukluklari Circadian Rhythm Sleep Disorders
Akıncı, E., & Orhan, F. Ö. (2016)
Advance -R elated Complaints and Advanced Sleep Phase Disorder
Auger, R. R. (2009)
The Circadian Clock and its Genes: in the Brain and Beyond
Hastings, M. H., & Maywood, E. S. (2006)
Altered PPI Due to Mutations in hPER2 and CKI Delta Locus, Causing ASPS
Ali, A., & Bagchi, A. (2016) · Advances in intelligent systems and computing · doi:10.1007/978-981-10-2035-3_1
Evaluation and Management of Circadian Rhythm Sleep Disorders
Abbott, S. M., & Zee, P. C. (2017) · Springer eBooks · doi:10.1007/978-1-4939-6578-6_48
Greco, J. (2013) · TSpace (University of Toronto)
徐, 璎., & 许, 丽. (2017) · Scientia Sinica Vitae · doi:10.1360/n052017-00258
Ling, H. H. (2014) · TSpace (University of Toronto)
Trastornos del ritmo circadiano
Mahowald, M. W., & Ettinger, M. G. (2011) · Elsevier eBooks · doi:10.1016/b978-84-8086-733-7.00034-6
Aspectos genéticos y trastornos del sueño en el ser humano y en los animales de experimentación
Maret, S., Dauvilliers, Y. A., & Tafti, M. (2011) · Elsevier eBooks · doi:10.1016/b978-84-8086-733-7.00022-x
Occupational Health and Sleep Issues in Underserved Populations
Kalliny, M., & McKenzie, J. G. (2018) · Physician Assistant Clinics · doi:10.1016/j.cpha.2018.08.005
Huang, G., & Wang, Y. (2020) · Springer eBooks · doi:10.1007/978-981-15-2481-3_9
Entrainment of the circadian clock in humans: mechanism and implications for sleep disorders.
Metcalfe, D. (2007) · DOAJ (DOAJ: Directory of Open Access Journals)
Genetics of sleep–wake disorders
Mazzotti, D. R., Pack, A. I., & Gehrman, P. (2020) · doi:10.1093/med/9780198713005.003.0112
Genetic contribution in primary sleep disorders
Gutiérrez-Amavizca, B. E., Gutiérrez-Amavizca, J. P., & Pérez-León, J. A. (2019) · PubMed
Mahowald, M. W., & Ettinger, M. G. (2009) · Elsevier eBooks · doi:10.1016/b978-0-7506-7584-0.00034-3
Opiol, H. (2019) · Spectrum Research Repository (Concordia University)
The whole is greater than the sum of the parts
Ptáček, L. J., & Fu, Y. (2021) · Journal of Clinical Investigation · doi:10.1172/jci145965
Self-citationThe Role of BMAL1 in Linking the Molecular Clock and Circadian Rhythm of Cerebral Myogenic Tone
Shaw, E. A. S. (2021) · TSpace (University of Toronto)
Classification, Mechanism, Biochemistry, and Genetics of Headache
Ahn, A. H. (2015) · Elsevier eBooks · doi:10.1016/b978-0-12-800901-7.00002-1
Studying Human Circadian Behaviour Using Peripheral Cells
Pagani, L., Eckert, A., & Brown, S. A. (2010) · Advances in neurobiology · doi:10.1007/978-1-4419-7197-5_11
Vorverlagerte Schlafphasenstörung
Popp, R. (2020) · Elsevier eBooks · doi:10.1016/b978-3-437-21321-2.00031-4
Metadata
- Authors
- Xu, Y., Padiath, Q. S., Shapiro, R. E., Jones, C. R., Wu, S. C., Saigoh, N., Saigoh, K., Ptáček, L. J., & Fu, Y.-H.
- Affiliations
- University of California, San Francisco (US)
- University of Vermont (US)
- University of Utah (US)
- Howard Hughes Medical Institute (US)
- Corresponding author
- Fu, Ying-Hui
- ORCID
- Venue
- Nature
- Published
- 2005-03
- Volume
- 434
- Issue
- 7033
- Pages
- 640-644
- ISSN
- 0028-0836 (ISSN-L)
- 1476-4687
- OpenAlex
- W1974495707
- Cited by
- 861
- References
- 30
- Citations by year
- 2026: 14 · 2025: 19 · 2024: 33 · 2023: 27 · 2022: 40 · 2021: 33 · 2020: 48 · 2019: 40 · 2018: 37 · 2017: 38 · 2016: 33 · 2015: 32 · 2014: 43 · 2013: 53 · 2012: 42
- FWCI
- 20.52
- Type
- journal article
- Language
- en
- Open access
- closed
- Licence
- www.springer.com/tdm (tdm)
- Locations
- Nature (publishedVersion)
- PubMed (publishedVersion)
- RePEc: Research Papers in Economics (submittedVersion)
- Funders
- Howard Hughes Medical Institute
- Deutsches Krebsforschungszentrum
- Stryker
- National Institutes of Health
- Topics
- Life Sciences › Neuroscience › Endocrine and Autonomic Systems › Circadian rhythm and melatonin
- Life Sciences › Neuroscience › Cognitive Neuroscience › Sleep and Wakefulness Research
- Social Sciences › Psychology › Experimental and Cognitive Psychology › Sleep and Work-Related Fatigue
- Keywords
- CK1δ, circadian rhythm, melatonin rhythm, transgenic Drosophila, transgenic mice, circadian period, clock gene regulation, sleep disorders
- MeSH terms
- Amino Acid Sequence, Animals, Caseins, Circadian Rhythm, Darkness, Drosophila melanogaster, Female, Humans, Light, Male, Mice, Transgenic, Molecular Sequence Data, Motor Activity, Pedigree, Phenotype, Phosvitin, Sleep Wake Disorders, Syndrome, Time Factors, Mutation, Missense, Animals, Genetically Modified, Casein Kinase Idelta, Mice
About these checks
Registry, retraction, Cites and statistics results are computed, not judged, with one exception: a printed reference that no index lists is read once by a model before it counts as a citation error. Claims are extracted by a model and kept only when their quote appears verbatim in the text; each cited source is then checked, with a model’s help, for whether it says what the claim relies on. Those verdicts can be wrong — read the claim’s quote and the cited source before relying on one.
Statistics and arithmetic are recomputed, not judged.
Confidence bands are shown only for fields calibrated on our annotated test set. None is calibrated yet, so no band is shown.
What counts as a claim ›How we measure confidence ›How we check this ›
Are you an author, or do you see a problem with this page? Request a review