Mediation analysis demonstrates that trans-eQTLs are often explained by cis-mediation: a genome-wide analysis among 1,800 South Asians.
A large fraction of human genes are regulated by genetic variation near the transcribed sequence (cis-eQTL, expression quantitative trait locus), and many cis-eQTLs have implications for human disease. Less is known regarding the effects of genetic variation on expression of distant genes (trans-eQT...
| Main Authors: | , , , , , , , , , , , , , , , , |
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| Format: | Article |
| Language: | English |
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Public Library of Science (PLoS)
2014-12-01
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| Series: | PLoS Genetics |
| Online Access: | http://europepmc.org/articles/PMC4256471?pdf=render |
| _version_ | 1818544181865349120 |
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| author | Brandon L Pierce Lin Tong Lin S Chen Ronald Rahaman Maria Argos Farzana Jasmine Shantanu Roy Rachelle Paul-Brutus Harm-Jan Westra Lude Franke Tonu Esko Rakibuz Zaman Tariqul Islam Mahfuzar Rahman John A Baron Muhammad G Kibriya Habibul Ahsan |
| author_facet | Brandon L Pierce Lin Tong Lin S Chen Ronald Rahaman Maria Argos Farzana Jasmine Shantanu Roy Rachelle Paul-Brutus Harm-Jan Westra Lude Franke Tonu Esko Rakibuz Zaman Tariqul Islam Mahfuzar Rahman John A Baron Muhammad G Kibriya Habibul Ahsan |
| author_sort | Brandon L Pierce |
| collection | DOAJ |
| description | A large fraction of human genes are regulated by genetic variation near the transcribed sequence (cis-eQTL, expression quantitative trait locus), and many cis-eQTLs have implications for human disease. Less is known regarding the effects of genetic variation on expression of distant genes (trans-eQTLs) and their biological mechanisms. In this work, we use genome-wide data on SNPs and array-based expression measures from mononuclear cells obtained from a population-based cohort of 1,799 Bangladeshi individuals to characterize cis- and trans-eQTLs and determine if observed trans-eQTL associations are mediated by expression of transcripts in cis with the SNPs showing trans-association, using Sobel tests of mediation. We observed 434 independent trans-eQTL associations at a false-discovery rate of 0.05, and 189 of these trans-eQTLs were also cis-eQTLs (enrichment P<0.0001). Among these 189 trans-eQTL associations, 39 were significantly attenuated after adjusting for a cis-mediator based on Sobel P<10-5. We attempted to replicate 21 of these mediation signals in two European cohorts, and while only 7 trans-eQTL associations were present in one or both cohorts, 6 showed evidence of cis-mediation. Analyses of simulated data show that complete mediation will be observed as partial mediation in the presence of mediator measurement error or imperfect LD between measured and causal variants. Our data demonstrates that trans-associations can become significantly stronger or switch directions after adjusting for a potential mediator. Using simulated data, we demonstrate that this phenomenon is expected in the presence of strong cis-trans confounding and when the measured cis-transcript is correlated with the true (unmeasured) mediator. In conclusion, by applying mediation analysis to eQTL data, we show that a substantial fraction of observed trans-eQTL associations can be explained by cis-mediation. Future studies should focus on understanding the mechanisms underlying widespread cis-mediation and their relevance to disease biology, as well as using mediation analysis to improve eQTL discovery. |
| first_indexed | 2024-12-11T22:45:07Z |
| format | Article |
| id | doaj.art-f84d39bed17c4a9b8346b19219fd086b |
| institution | Directory Open Access Journal |
| issn | 1553-7390 1553-7404 |
| language | English |
| last_indexed | 2024-12-11T22:45:07Z |
| publishDate | 2014-12-01 |
| publisher | Public Library of Science (PLoS) |
| record_format | Article |
| series | PLoS Genetics |
| spelling | doaj.art-f84d39bed17c4a9b8346b19219fd086b2022-12-22T00:47:39ZengPublic Library of Science (PLoS)PLoS Genetics1553-73901553-74042014-12-011012e100481810.1371/journal.pgen.1004818Mediation analysis demonstrates that trans-eQTLs are often explained by cis-mediation: a genome-wide analysis among 1,800 South Asians.Brandon L PierceLin TongLin S ChenRonald RahamanMaria ArgosFarzana JasmineShantanu RoyRachelle Paul-BrutusHarm-Jan WestraLude FrankeTonu EskoRakibuz ZamanTariqul IslamMahfuzar RahmanJohn A BaronMuhammad G KibriyaHabibul AhsanA large fraction of human genes are regulated by genetic variation near the transcribed sequence (cis-eQTL, expression quantitative trait locus), and many cis-eQTLs have implications for human disease. Less is known regarding the effects of genetic variation on expression of distant genes (trans-eQTLs) and their biological mechanisms. In this work, we use genome-wide data on SNPs and array-based expression measures from mononuclear cells obtained from a population-based cohort of 1,799 Bangladeshi individuals to characterize cis- and trans-eQTLs and determine if observed trans-eQTL associations are mediated by expression of transcripts in cis with the SNPs showing trans-association, using Sobel tests of mediation. We observed 434 independent trans-eQTL associations at a false-discovery rate of 0.05, and 189 of these trans-eQTLs were also cis-eQTLs (enrichment P<0.0001). Among these 189 trans-eQTL associations, 39 were significantly attenuated after adjusting for a cis-mediator based on Sobel P<10-5. We attempted to replicate 21 of these mediation signals in two European cohorts, and while only 7 trans-eQTL associations were present in one or both cohorts, 6 showed evidence of cis-mediation. Analyses of simulated data show that complete mediation will be observed as partial mediation in the presence of mediator measurement error or imperfect LD between measured and causal variants. Our data demonstrates that trans-associations can become significantly stronger or switch directions after adjusting for a potential mediator. Using simulated data, we demonstrate that this phenomenon is expected in the presence of strong cis-trans confounding and when the measured cis-transcript is correlated with the true (unmeasured) mediator. In conclusion, by applying mediation analysis to eQTL data, we show that a substantial fraction of observed trans-eQTL associations can be explained by cis-mediation. Future studies should focus on understanding the mechanisms underlying widespread cis-mediation and their relevance to disease biology, as well as using mediation analysis to improve eQTL discovery.http://europepmc.org/articles/PMC4256471?pdf=render |
| spellingShingle | Brandon L Pierce Lin Tong Lin S Chen Ronald Rahaman Maria Argos Farzana Jasmine Shantanu Roy Rachelle Paul-Brutus Harm-Jan Westra Lude Franke Tonu Esko Rakibuz Zaman Tariqul Islam Mahfuzar Rahman John A Baron Muhammad G Kibriya Habibul Ahsan Mediation analysis demonstrates that trans-eQTLs are often explained by cis-mediation: a genome-wide analysis among 1,800 South Asians. PLoS Genetics |
| title | Mediation analysis demonstrates that trans-eQTLs are often explained by cis-mediation: a genome-wide analysis among 1,800 South Asians. |
| title_full | Mediation analysis demonstrates that trans-eQTLs are often explained by cis-mediation: a genome-wide analysis among 1,800 South Asians. |
| title_fullStr | Mediation analysis demonstrates that trans-eQTLs are often explained by cis-mediation: a genome-wide analysis among 1,800 South Asians. |
| title_full_unstemmed | Mediation analysis demonstrates that trans-eQTLs are often explained by cis-mediation: a genome-wide analysis among 1,800 South Asians. |
| title_short | Mediation analysis demonstrates that trans-eQTLs are often explained by cis-mediation: a genome-wide analysis among 1,800 South Asians. |
| title_sort | mediation analysis demonstrates that trans eqtls are often explained by cis mediation a genome wide analysis among 1 800 south asians |
| url | http://europepmc.org/articles/PMC4256471?pdf=render |
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