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Research Article

A Systematic Survey of Loss-of-Function Variants in Human Protein-Coding Genes

Science
17 Feb 2012
Vol 335, Issue 6070
pp. 823-828

Defective Gene Detective

Identifying genes that give rise to diseases is one of the major goals of sequencing human genomes. However, putative loss-of-function genes, which are often some of the first identified targets of genome and exome sequencing, have often turned out to be sequencing errors rather than true genetic variants. In order to identify the true scope of loss-of-function genes within the human genome, MacArthur et al. (p. 823; see the Perspective by Quintana-Murci) extensively validated the genomes from the 1000 Genomes Project, as well as an additional European individual, and found that the average person has about 100 true loss-of-function alleles of which approximately 20 have two copies within an individual. Because many known disease-causing genes were identified in “normal” individuals, the process of clinical sequencing needs to reassess how to identify likely causative alleles.

Abstract

Genome-sequencing studies indicate that all humans carry many genetic variants predicted to cause loss of function (LoF) of protein-coding genes, suggesting unexpected redundancy in the human genome. Here we apply stringent filters to 2951 putative LoF variants obtained from 185 human genomes to determine their true prevalence and properties. We estimate that human genomes typically contain ~100 genuine LoF variants with ~20 genes completely inactivated. We identify rare and likely deleterious LoF alleles, including 26 known and 21 predicted severe disease–causing variants, as well as common LoF variants in nonessential genes. We describe functional and evolutionary differences between LoF-tolerant and recessive disease genes and a method for using these differences to prioritize candidate genes found in clinical sequencing studies.

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References and Notes

1
Ng P. C., et al., Genetic variation in an individual human exome. PLoS Genet. 4, e1000160 (2008).
2
The 1000 Genomes Project Consortium, A map of human genome variation from population-scale sequencing. Nature 467, 1061 (2010).
3
Pelak K., et al., The characterization of twenty sequenced human genomes. PLoS Genet. 6, e1001111 (2010).
4
MacArthur D. G., Tyler-Smith C., Loss-of-function variants in the genomes of healthy humans. Hum. Mol. Genet. 19, (R2), R125 (2010).
5
Balasubramanian S., et al., Gene inactivation and its implications for annotation in the era of personal genomics. Genes Dev. 25, 1 (2011).
6
DePristo M. A., et al., A framework for variation discovery and genotyping using next-generation DNA sequencing data. Nat. Genet. 43, 491 (2011).
7
Harrow J., et al., GENCODE: Producing a reference annotation for ENCODE. Genome Biol. 7 (suppl. 1), S4–, 1 (2006).
9
See supporting material on Science Online.
10
Mills R. E., et al.1000 Genomes Project, Mapping copy number variation by population-scale genome sequencing. Nature 470, 59 (2011).
11
Uzumcu A., et al., Loss of desmoplakin isoform I causes early onset cardiomyopathy and heart failure in a Naxos-like syndrome. J. Med. Genet. 43, e5 (2006).
12
MacArthur D. G., et al., Loss of ACTN3 gene function alters mouse muscle metabolism and shows evidence of positive selection in humans. Nat. Genet. 39, 1261 (2007).
13
Xue Y., et al., Spread of an inactive form of caspase-12 in humans is due to recent positive selection. Am. J. Hum. Genet. 78, 659 (2006).
14
Zhang Z. D., Frankish A., Hunt T., Harrow J., Gerstein M., Identification and analysis of unitary pseudogenes: Historic and contemporary gene losses in humans and other primates. Genome Biol. 11, R26 (2010).
15
Yngvadottir B., et al., A genome-wide survey of the prevalence and evolutionary forces acting on human nonsense SNPs. Am. J. Hum. Genet. 84, 224 (2009).
16
Lupski J. R., et al., Whole-genome sequencing in a patient with Charcot-Marie-Tooth neuropathy. N. Engl. J. Med. 362, 1181 (2010).
17
Chen J. M., Cooper D. N., Chuzhanova N., Férec C., Patrinos G. P., Gene conversion: Mechanisms, evolution and human disease. Nat. Rev. Genet. 8, 762 (2007).
18
Casola C., Zekonyte U., Phillips A. D., Cooper D. N., Hahn M. W., Interlocus gene conversion events introduce deleterious mutations into at least 1% of human genes associated with inherited disease. Genome Res. 10.1101/gr.127738.111 (2011).
19
Huang N., Lee I., Marcotte E. M., Hurles M. E., Characterising and predicting haploinsufficiency in the human genome. PLoS Genet. 6, e1001154 (2010).
20
Ishimaru Y., et al., Transient receptor potential family members PKD1L3 and PKD2L1 form a candidate sour taste receptor. Proc. Natl. Acad. Sci. U.S.A. 103, 12569 (2006).
21
Huang A. L., et al., The cells and logic for mammalian sour taste detection. Nature 442, 934 (2006).
22
Wellcome Trust Case Control Consortium, Genome-wide association study of 14,000 cases of seven common diseases and 3,000 shared controls. Nature 447, 661 (2007).
23
Conrad D. F., et al., Origins and functional impact of copy number variation in the human genome. Nature 464, 704 (2010).
24
Montgomery S. B., et al., Transcriptome genetics using second generation sequencing in a Caucasian population. Nature 464, 773 (2010).
25
Pickrell J. K., et al., Understanding mechanisms underlying human gene expression variation with RNA sequencing. Nature 464, 768 (2010).
26
Nagy E., Maquat L. E., A rule for termination-codon position within intron-containing genes: When nonsense affects RNA abundance. Trends Biochem. Sci. 23, 198 (1998).
27
Olson M. V., When less is more: Gene loss as an engine of evolutionary change. Am. J. Hum. Genet. 64, 18 (1999).
28
Fry A. E., et al., Positive selection of a CD36 nonsense variant in sub-Saharan Africa, but no association with severe malaria phenotypes. Hum. Mol. Genet. 18, 2683 (2009).
29
Bittles A. H., Neel J. V., The costs of human inbreeding and their implications for variations at the DNA level. Nat. Genet. 8, 117 (1994).
30
McCune A. R., et al., A low genomic number of recessive lethals in natural populations of bluefin killifish and zebrafish. Science 296, 2398 (2002).
31
Albers C. A., et al., Dindel: Accurate indel calls from short-read data. Genome Res. 21, 961 (2011).
32
McCarroll S. A., et al., Integrated detection and population-genetic analysis of SNPs and copy number variation. Nat. Genet. 40, 1166 (2008).
33
Kidd J. M., et al., Haplotype sorting using human fosmid clone end-sequence pairs. Genome Res. 18, 2016 (2008).
34
McKenna A., et al., The Genome Analysis Toolkit: A MapReduce framework for analyzing next-generation DNA sequencing data. Genome Res. 20, 1297 (2010).
35
Wang K., Li M., Hakonarson H., ANNOVAR: Functional annotation of genetic variants from high-throughput sequencing data. Nucleic Acids Res. 38, e164 (2010).
36
Kidd J. M., et al., Mapping and sequencing of structural variation from eight human genomes. Nature 453, 56 (2008).
37
Chen K., et al., BreakDancer: An algorithm for high-resolution mapping of genomic structural variation. Nat. Methods 6, 677 (2009).
38
Ye K., Schulz M. H., Long Q., Apweiler R., Ning Z., Pindel: A pattern growth approach to detect break points of large deletions and medium sized insertions from paired-end short reads. Bioinformatics 25, 2865 (2009).
39
Morris J. A., Randall J. C., Maller J. B., Barrett J. C., Evoker: A visualization tool for genotype intensity data. Bioinformatics 26, 1786 (2010).
40
Robinson J. T., et al., Integrative genomics viewer. Nat. Biotechnol. 29, 24 (2011).
41
Paten B., Herrero J., Beal K., Fitzgerald S., Birney E., Enredo and Pecan: Genome-wide mammalian consistency-based multiple alignment with paralogs. Genome Res. 18, 1814 (2008).
42
Altschul S. F., et al., Gapped BLAST and PSI-BLAST: A new generation of protein database search programs. Nucleic Acids Res. 25, 3389 (1997).
43
Mott R., EST_GENOME: A program to align spliced DNA sequences to unspliced genomic DNA. Comput. Appl. Biosci. 13, 477 (1997).
44
Searle S. M., Gilbert J., Iyer V., Clamp M., The otter annotation system. Genome Res. 14, 963 (2004).
45
Sonnhammer E. L., Wootton J. C., Integrated graphical analysis of protein sequence features predicted from sequence composition. Proteins 45, 262 (2001).
46
Bateman A., et al., The Pfam protein families database. Nucleic Acids Res. 32 (Database issue), D138 (2004).
47
Zhang J., Maquat L. E., Evidence that the decay of nucleus-associated nonsense mRNA for human triosephosphate isomerase involves nonsense codon recognition after splicing. RNA 2, 235 (1996).
48
Flicek P., et al., Ensembl 2011. Nucleic Acids Res. 39 (Database issue), D800 (2011).
49
Pruitt K. D., et al., The consensus coding sequence (CCDS) project: Identifying a common protein-coding gene set for the human and mouse genomes. Genome Res. 19, 1316 (2009).
50
Katada S., Tanaka M., Touhara K., Structural determinants for membrane trafficking and G protein selectivity of a mouse olfactory receptor. J. Neurochem. 90, 1453 (2004).
51
Krawczak M., Reiss J., Cooper D. N., The mutational spectrum of single base-pair substitutions in mRNA splice junctions of human genes: Causes and consequences. Hum. Genet. 90, 41 (1992).
52
Chillón M., et al., A novel donor splice site in intron 11 of the CFTR gene, created by mutation 1811+1.6kbA—>G, produces a new exon: High frequency in Spanish cystic fibrosis chromosomes and association with severe phenotype. Am. J. Hum. Genet. 56, 623 (1995).
53
Baralle D., Baralle M., Splicing in action: Assessing disease causing sequence changes. J. Med. Genet. 42, 737 (2005).
54
Chambliss K. L., et al., Two exon-skipping mutations as the molecular basis of succinic semialdehyde dehydrogenase deficiency (4-hydroxybutyric aciduria). Am. J. Hum. Genet. 63, 399 (1998).
55
Wilson E. B., Probable inference, the law of succession, and statistical inference. J. Am. Stat. Assoc. 22, 209 (1927).
56
Barrett J. C., et al.Type 1 Diabetes Genetics Consortium, Genome-wide association study and meta-analysis find that over 40 loci affect risk of type 1 diabetes. Nat. Genet. 41, 703 (2009).
57
Tajima F., Statistical method for testing the neutral mutation hypothesis by DNA polymorphism. Genetics 123, 585 (1989).
58
Fay J. C., Wu C. I., Hitchhiking under positive Darwinian selection. Genetics 155, 1405 (2000).
59
Nielsen R., et al., Genomic scans for selective sweeps using SNP data. Genome Res. 15, 1566 (2005).
60
Schaffner S. F., et al., Calibrating a coalescent simulation of human genome sequence variation. Genome Res. 15, 1576 (2005).
61
Sabeti P. C., et al., Genome-wide detection and characterization of positive selection in human populations. Nature 449, 913 (2007).
62
Voight B. F., Kudaravalli S., Wen X., Pritchard J. K., A map of recent positive selection in the human genome. PLoS Biol. 4, e72 (2006).
63
Cooper G. M., et al., Distribution and intensity of constraint in mammalian genomic sequence. Genome Res. 15, 901 (2005).
64
Brown K. R., Jurisica I., Online predicted human interaction database. Bioinformatics 21, 2076 (2005).
65
Ceol A., et al., MINT, the molecular interaction database: 2009 update. Nucleic Acids Res. 38 (Database issue), D532 (2010).
66
Keshava Prasad T. S., et al., Human Protein Reference Database—2009 update. Nucleic Acids Res. 37 (Database issue), D767 (2009).
67
Rual J. F., et al., Towards a proteome-scale map of the human protein-protein interaction network. Nature 437, 1173 (2005).
68
Lee I., Li Z., Marcotte E. M., An improved, bias-reduced probabilistic functional gene network of baker’s yeast, Saccharomyces cerevisiae. PLoS ONE 2, e988 (2007).
69
Lee I., et al., A single gene network accurately predicts phenotypic effects of gene perturbation in Caenorhabditis elegans. Nat. Genet. 40, 181 (2008).
70
Van Dongen S., Graph clustering via a discrete uncoupling process. SIAM J. Matrix Anal. Appl. 30, 121 (2008).
71
Bin J., et al., BBS7 and TTC8 (BBS8) mutations play a minor role in the mutational load of Bardet-Biedl syndrome in a multiethnic population. Hum. Mutat. 30, E737 (2009).

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Information

Published In

Science
Volume 335 | Issue 6070
17 February 2012

Submission history

Received: 10 October 2011
Accepted: 11 January 2012
Published in print: 17 February 2012

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Acknowledgments

T. Shah provided the Pyvoker software used for manual assignment of genotypes based on intensity clusters; S. Edkins was involved in the Sequenom validation; and the genotyping groups at Illumina, the Wellcome Trust Sanger Institute, and The Broad Institute of Harvard and MIT provided raw intensity data for the three Illumina arrays used for genotyping validation. The work performed at the Wellcome Trust Sanger Institute was supported by Wellcome Trust grant 098051; D.G.M. was supported by a fellowship from the Australian National Health and Medical Research Council; G.L. by the Wellcome Trust (090532/Z/09/Z); E.T.D. and S.B.M. by the Swiss National Science Foundation, the Louis Jeantet Foundation, and the NIH–National Institute of Mental Health GTEx fund; K.Y. by the Netherlands Organisation for Scientific Research (NWO) VENI grant 639.021.125; and H.Z., Y.L., and J.W. by a National Basic Research Program of China (973 program no. 2011CB809200), the National Natural Science Foundation of China (30725008, 30890032, 30811130531), the Chinese 863 program (2006AA02A302, 2009AA022707), the Shenzhen Municipal Government of China (grants JC200903190767A, JC200903190772A, ZYC200903240076A, CXB200903110066A, ZYC200903240077A, and ZYC200903240080A), and the Ole Rømer grant from the Danish Natural Science Research Council, as well as funding from the Shenzhen Municipal Government and the Local Government of Yantian District of Shenzhen. M.B.G. and C.T.-S. contributed equally to this work as senior authors. J.K.P. is on the scientific advisory board of 23andMe, and R.A.G. has a shared investment in Life Technologies. Raw sequence data for the 1000 Genomes pilot projects are available from www.1000genomes.org, and a curated list of the loss-of-function variants described in this manuscript is provided in the supporting online material.

Authors

Affiliations

Daniel G. MacArthur* [email protected]
Wellcome Trust Sanger Institute, Hinxton CB10 1SA, UK.
Discipline of Paediatrics and Child Health, University of Sydney, Sydney, NSW 2006, Australia.
Suganthi Balasubramanian
Program in Computational Biology and Bioinformatics, Yale University, New Haven, CT 06520, USA.
Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520, USA.
Adam Frankish
Wellcome Trust Sanger Institute, Hinxton CB10 1SA, UK.
Ni Huang
Wellcome Trust Sanger Institute, Hinxton CB10 1SA, UK.
James Morris
Wellcome Trust Sanger Institute, Hinxton CB10 1SA, UK.
Klaudia Walter
Wellcome Trust Sanger Institute, Hinxton CB10 1SA, UK.
Luke Jostins
Wellcome Trust Sanger Institute, Hinxton CB10 1SA, UK.
Lukas Habegger
Program in Computational Biology and Bioinformatics, Yale University, New Haven, CT 06520, USA.
Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520, USA.
Joseph K. Pickrell
Department of Human Genetics, University of Chicago, Chicago, IL 60637, USA.
Stephen B. Montgomery
Departments of Pathology and Genetics, Stanford University, Stanford, CA 94305–5324, USA.
Department of Genetic Medicine and Development, University of Geneva Medical School, 1211 Geneva 4, Switzerland.
Cornelis A. Albers
Wellcome Trust Sanger Institute, Hinxton CB10 1SA, UK.
Department of Haematology, University of Cambridge and NHS Blood and Transplant, Cambridge CB2 0PT, UK.
Zhengdong D. Zhang
Department of Genetics, Albert Einstein College of Medicine, Bronx, NY 10461, USA.
Donald F. Conrad
Department of Genetics, Washington University School of Medicine, Saint Louis, MO 63110, USA.
Gerton Lunter
Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, UK.
Hancheng Zheng
BGI-Shenzhen, Shenzhen 518083, China.
Qasim Ayub
Wellcome Trust Sanger Institute, Hinxton CB10 1SA, UK.
Mark A. DePristo
Program in Medical and Population Genetics, Broad Institute of Harvard and MIT, Cambridge, MA 02142, USA.
Eric Banks
Program in Medical and Population Genetics, Broad Institute of Harvard and MIT, Cambridge, MA 02142, USA.
Min Hu
Wellcome Trust Sanger Institute, Hinxton CB10 1SA, UK.
Robert E. Handsaker
Program in Medical and Population Genetics, Broad Institute of Harvard and MIT, Cambridge, MA 02142, USA.
Department of Genetics, Harvard Medical School, Boston, MA 02115, USA.
Jeffrey A. Rosenfeld
IST/High Performance and Research Computing, University of Medicine and Dentistry of New Jersey, Newark, NJ 07103, USA.
Menachem Fromer
Program in Medical and Population Genetics, Broad Institute of Harvard and MIT, Cambridge, MA 02142, USA.
Mike Jin
Program in Computational Biology and Bioinformatics, Yale University, New Haven, CT 06520, USA.
Xinmeng Jasmine Mu
Program in Computational Biology and Bioinformatics, Yale University, New Haven, CT 06520, USA.
Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520, USA.
Ekta Khurana
Program in Computational Biology and Bioinformatics, Yale University, New Haven, CT 06520, USA.
Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520, USA.
Kai Ye
Molecular Epidemiology Section, Leiden University Medical Center, 2300 RC Leiden, Netherlands.
Mike Kay
Wellcome Trust Sanger Institute, Hinxton CB10 1SA, UK.
Gary Ian Saunders
Wellcome Trust Sanger Institute, Hinxton CB10 1SA, UK.
Marie-Marthe Suner
Wellcome Trust Sanger Institute, Hinxton CB10 1SA, UK.
Toby Hunt
Wellcome Trust Sanger Institute, Hinxton CB10 1SA, UK.
If H. A. Barnes
Wellcome Trust Sanger Institute, Hinxton CB10 1SA, UK.
Clara Amid
Wellcome Trust Sanger Institute, Hinxton CB10 1SA, UK.
The European Nucleotide Archive, European Molecular Biology Laboratory–European Bioinformatics Institute, Hinxton CB10 1SD, UK.
Denise R. Carvalho-Silva
Wellcome Trust Sanger Institute, Hinxton CB10 1SA, UK.
Alexandra H. Bignell
Wellcome Trust Sanger Institute, Hinxton CB10 1SA, UK.
Catherine Snow
Wellcome Trust Sanger Institute, Hinxton CB10 1SA, UK.
Bryndis Yngvadottir
Wellcome Trust Sanger Institute, Hinxton CB10 1SA, UK.
Suzannah Bumpstead
Wellcome Trust Sanger Institute, Hinxton CB10 1SA, UK.
David N. Cooper
Institute of Medical Genetics, School of Medicine, Cardiff University, Heath Park, Cardiff CF14 4XN, UK.
Yali Xue
Wellcome Trust Sanger Institute, Hinxton CB10 1SA, UK.
Irene Gallego Romero
Wellcome Trust Sanger Institute, Hinxton CB10 1SA, UK.
Department of Human Genetics, University of Chicago, Chicago, IL 60637, USA.
1000 Genomes Project Consortium
Jun Wang
BGI-Shenzhen, Shenzhen 518083, China.
Yingrui Li
BGI-Shenzhen, Shenzhen 518083, China.
Richard A. Gibbs
Human Genome Sequencing Center, Baylor College of Medicine, Houston, TX 77030, USA.
Steven A. McCarroll
Program in Medical and Population Genetics, Broad Institute of Harvard and MIT, Cambridge, MA 02142, USA.
Department of Genetics, Harvard Medical School, Boston, MA 02115, USA.
Emmanouil T. Dermitzakis
Department of Genetic Medicine and Development, University of Geneva Medical School, 1211 Geneva 4, Switzerland.
Jonathan K. Pritchard
Department of Human Genetics, University of Chicago, Chicago, IL 60637, USA.
Howard Hughes Medical Institute, University of Chicago, Chicago, IL 60637, USA.
Jeffrey C. Barrett
Wellcome Trust Sanger Institute, Hinxton CB10 1SA, UK.
Jennifer Harrow
Wellcome Trust Sanger Institute, Hinxton CB10 1SA, UK.
Matthew E. Hurles
Wellcome Trust Sanger Institute, Hinxton CB10 1SA, UK.
Mark B. Gerstein
Program in Computational Biology and Bioinformatics, Yale University, New Haven, CT 06520, USA.
Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520, USA.
Department of Computer Science, Yale University, New Haven, CT, USA.
Chris Tyler-Smith
Wellcome Trust Sanger Institute, Hinxton CB10 1SA, UK.

Notes

*
To whom correspondence should be addressed. E-mail: [email protected]
These authors contributed equally to this work.

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