Mendelian randomization in health research: Using appropriate genetic variants and avoiding biased estimates

Economics and Human Biology

Volumn 13, Issue 1, 2014, Pages 99-106

  Taylor, Amy E ^a   Davies, Neil M ^a   Ware, Jennifer J ^a   Vanderweele, Tyler ^b   Smith, George Davey ^a   Munafò, Marcus R ^a  

^a UNIVERSITY OF BRISTOL   (United Kingdom)

^b HARVARD SCHOOL OF PUBLIC HEALTH   (United States)

Author keywords

Causal inference; Instrumental variable; Mendelian randomization; Smoking; Tobacco

Indexed keywords

COTININE; CYTOCHROME P450 2D6; NICOTINIC RECEPTOR;

ALLELE; ARTICLE; GENETIC ASSOCIATION; GENETIC VARIABILITY; MEDICAL RESEARCH; MENDELIAN RANDOMIZATION ANALYSIS; PLEIOTROPY; SINGLE NUCLEOTIDE POLYMORPHISM; SMOKING; BEHAVIOR; CAUSAL ATTRIBUTION; GENE CLUSTER; HUMAN; TOBACCO;

CAUSAL INFERENCE; INSTRUMENTAL VARIABLE; MENDELIAN RANDOMIZATION; SMOKING; TOBACCO;

BIAS (EPIDEMIOLOGY); CAUSALITY; CONFOUNDING FACTORS (EPIDEMIOLOGY); GENOME-WIDE ASSOCIATION STUDY; HUMANS; MENDELIAN RANDOMIZATION ANALYSIS; RESEARCH DESIGN; SMOKING;

EID: 84896722557     PISSN: 1570677X     EISSN: 18736130     Source Type: Journal    
DOI: 10.1016/j.ehb.2013.12.002     Document Type: Article

References (51)

1. J.D. Angrist, G.W. Imbens, and D.B. Rubin Identification of causal effects using instrumental variables J. Am. Stat. Assoc. 91 1996 444 455
2. M. Benn, A. Tybjaerg-Hansen, S. Stender, R. Frikke-Schmidt, and B.G. Nordestgaard Low-density lipoprotein cholesterol and the risk of cancer: a Mendelian randomization study J. Natl. Cancer Inst. 103 2011 508 519
3. J.H. Bjorngaard, D. Gunnell, M.B. Elvestad, G. Davey Smith, F. Skorpen, and H. Krokan et al. The causal role of smoking in anxiety and depression: a Mendelian randomization analysis of the HUNT study Psychol. Med. 43 2013 711 719
4. S. Burgess, S.G. Thompson, and C.C.G. Collaboration Avoiding bias from weak instruments in Mendelian randomization studies Int. J. Epidemiol. 40 2011 755 764
5. D. Carslake, A. Fraser, G. Davey Smith, M. May, T. Palmer, J. Sterne, K. Silventoinen, P. Tynelius, D.A. Lawlor, and F. Rasmussen Associations of mortality with own height using son's height as an instrumental variable Econ. Hum. Biol. 11 2013 351 359
6. J.P. Casas, L.E. Bautista, L. Smeeth, P. Sharma, and A.D. Hingorani Homocysteine and stroke: evidence on a causal link from Mendelian randomisation Lancet 365 2005 224 232
7. P.S. Clarke, and F. Windmeijer Instrumental variable estimators for binary outcomes J. Am. Stat. Assoc. 107 2012 1638 1652
8. H.M. Colhoun, P.M. McKeigue, and G. Davey Smith Problems of reporting genetic associations with complex outcomes Lancet 361 2003 865 872
9. G.D. Davey Smith, and S. Ebrahim 'Mendelian randomization': can genetic epidemiology contribute to understanding environmental determinants of disease? Int. J. Epidemiol. 32 2003 1 22
10. G.D. Davey Smith, and S. Ebrahim Mendelian randomization: prospects, potentials, and limitations Int. J. Epidemiol. 33 2004 30 42
11. G. Davey Smith Use of genetic markers and gene-diet interactions for interrogating population-level causal influences of diet on health Genes Nutr. 6 2011 27 43
12. G. Davey Smith, and S. Ebrahim What can Mendelian randomisation tell us about modifiable behavioural and environmental exposures? BMJ 330 2005 1076 1079
13. G. Davey Smith, D.A. Lawlor, R. Harbord, N. Timpson, A. Rumley, G.D. Lowe, I.N. Day, and S. Ebrahim Association of C-reactive protein with blood pressure and hypertension: life course confounding and Mendelian randomization tests of causality Arterioscler. Thromb. Vasc. Biol. 25 2005 1051 1056
14. B.A. Ference, W. Yoo, I. Alesh, N. Mahajan, K.K. Mirowska, A. Mewada, J. Kahn, L. Afonso, K.A. Williams Sr.; and J.M. Flack Effect of long-term exposure to lower low-density lipoprotein cholesterol beginning early in life on the risk of coronary heart disease: a Mendelian randomization analysis J. Am. Coll. Cardiol. 60 2012 2631 2639
15. J.M. Fletcher, and S.F. Lehrer Genetic lotteries within families J. Health Econ. 30 2011 647 659
16. T.M. Frayling, N.J. Timpson, M.N. Weedon, E. Zeggini, R.M. Freathy, C.M. Lindgren, J.R. Perry, K.S. Elliott, H. Lango, N.W. Rayner, B. Shields, L.W. Harries, J.C. Barrett, S. Ellard, C.J. Groves, B. Knight, A.M. Patch, A.R. Ness, S. Ebrahim, D.A. Lawlor, S.M. Ring, Y. Ben-Shlomo, M.R. Jarvelin, U. Sovio, A.J. Bennett, D. Melzer, L. Ferrucci, R.J. Loos, I. Barroso, N.J. Wareham, F. Karpe, K.R. Owen, L.R. Cardon, M. Walker, G.A. Hitman, C.N. Palmer, A.S. Doney, A.D. Morris, G. Davey Smith, A.T. Hattersley, and M.I. McCarthy A common variant in the FTO gene is associated with body mass index and predisposes to childhood and adult obesity Science 316 2007 889 894
17. R.M. Freathy, G.R. Kazeem, R.W. Morris, P.C. Johnson, L. Paternoster, S. Ebrahim, A.T. Hattersley, A. Hill, A.D. Hingorani, C. Holst, B.J. Jefferis, S.I. Kring, V. Mooser, S. Padmanabhan, M. Preisig, S.M. Ring, N. Sattar, M.N. Upton, P. Vollenweider, G. Waeber, T.I. Sorensen, T.M. Frayling, G. Watt, D.A. Lawlor, P.H. Whincup, F. Tozzi, G. Davey Smith, and M. Munafò Genetic variation at CHRNA5-CHRNA3-CHRNB4 interacts with smoking status to influence body mass index Int. J. Epidemiol. 40 2011 1617 1628
18. R.M. Freathy, S.M. Ring, B. Shields, B. Galobardes, B. Knight, M.N. Weedon, G. Davey Smith, T.M. Frayling, and A.T. Hattersley A common genetic variant in the 15q24 nicotinic acetylcholine receptor gene cluster (CHRNA5-CHRNA3-CHRNB4) is associated with a reduced ability of women to quit smoking in pregnancy Hum. Mol. Genet. 18 2009 2922 2927
19. H. Furberg, Y. Kim, J. Dackor, E. Boerwinkle, N. Franceschini, D. Ardissino, L. Bernardinelli, P.M. Mannucci, F. Mauri, P.A. Merlini, D. Absher, T.L. Assimes, S.P. Fortmann, C. Iribarren, J.W. Knowles, T. Quertermous, L. Ferrucci, T. Tanaka, J.C. Bis, C.D. Furberg, T. Haritunians, B. McKnight, B.M. Psaty, K.D. Taylor, E.L. Thacker, P. Almgren, L. Groop, C. Ladenvall, M. Boehnke, A.U. Jackson, K.L. Mohlke, H.M. Stringham, J. Tuomilehto, E.J. Benjamin, S.J. Hwang, D. Levy, S.R. Preis, R.S. Vasan, J. Duan, P.V. Gejman, D.F. Levinson, A.R. Sanders, J.X. Shi, E.H. Lips, J.D. Mckay, A. Agudo, L. Barzan, V. Bencko, S. Benhamou, X. Castellsague, C. Canova, D.I. Conway, E. Fabianova, L. Foretova, V. Janout, C.M. Healy, I. Holcatova, K. Kjaerheim, P. Lagiou, J. Lissowska, R. Lowry, T.V. Macfarlane, D. Mates, L. Richiardi, P. Rudnai, N. Szeszenia-Dabrowska, D. Zaridze, A. Znaor, M. Lathrop, P. Brennan, S. Bandinelli, T.M. Frayling, J.M. Guralnik, Y. Milaneschi, J.R.B. Perry, D. Altshuler, R. Elosua, S. Kathiresan, G. Lucas, O. Melander, C.J. O'Donnell, V. Salomaa, S.M. Schwartz, B.F. Voight, B.W. Penninx, J.H. Smit, N. Vogelzangs, D.I. Boomsma, E.J.C. de Geus, J.M. Vink, G. Willemsen, S.J. Chanock, F.Y. Gu, S.E. Hankinson, D.J. Hunter, A. Hofman, H. Tiemeier, A.G. Uitterlinden, C.M. van Duijn, S. Walter, D.I. Chasman, B.M. Everett, G. Pare, P.M. Ridker, M.D. Li, H.H. Maes, J. Audrain-McGovern, D. Posthuma, L.M. Thornton, C. Lerman, J. Kaprio, J.E. Rose, J.P.A. Ioannidis, P. Kraft, D.Y. Lin, and P.F. Sullivan Genome-wide meta-analyses identify multiple loci associated with smoking behaviour Nat. Genet. 42 2010 441 447
20. M.M. Glymour, E.J. Tchetgen, and J.M. Robins Credible Mendelian randomization studies: approaches for evaluating the instrumental variable assumptions Am. J. Epidemiol. 175 2012 332 339
21. H.H. Goring, J.D. Terwilliger, and J. Blangero Large upward bias in estimation of locus-specific effects from genomewide scans Am. J. Hum. Genet. 69 2001 1357 1369
22. A. Hazra, P. Kraft, J. Selhub, E.L. Giovannucci, G. Thomas, R.N. Hoover, S.J. Chanock, and D.J. Hunter Common variants of FUT2 are associated with plasma vitamin B12 levels Nat. Genet. 40 2008 1160 1162
23. Interleukin-6 Receptor Mendelian Randomisation Analysis Consortium, A.D. Hingorani, and J.P. Casas The interleukin-6 receptor as a target for prevention of coronary heart disease: a Mendelian randomisation analysis Lancet 379 2012 1214 1224
24. J.P. Ioannidis Why most discovered true associations are inflated Epidemiology 19 2008 640 648
25. K. Keskitalo, U. Broms, M. Heliovaara, S. Ripatti, I. Surakka, M. Perola, J. Pitkaniemi, L. Peltonen, A. Aromaa, and J. Kaprio Association of serum cotinine level with a cluster of three nicotinic acetylcholine receptor genes (CHRNA3/CHRNA5/CHRNB4) on chromosome 15 Hum. Mol. Genet. 18 2009 4007 4012
26. D.A. Lawlor, R.M. Harbord, J.A. Sterne, N. Timpson, and G. Davey Smith Mendelian randomization: using genes as instruments for making causal inferences in epidemiology Stat. Med. 27 2008 1133 1163
27. D.A. Lawlor, F. Windmeijer, and G. Davey Smith Is Mendelian randomization 'lost in translation?' Comments on 'Mendelian randomization equals instrumental variable analysis with genetic instruments' by Wehby et al. Stat. Med. 27 2008 2750 2755
28. S.J. Lewis, R. Araya, G. Davey Smith, R. Freathy, D. Gunnell, T. Palmer, and M. Munafò Smoking is associated with, but does not cause, depressed mood in pregnancy - a Mendelian randomization study PLoS ONE 6 2011 e21689
29. E.H. Lips, V. Gaborieau, J.D. McKay, A. Chabrier, R.J. Hung, P. Boffetta, M. Hashibe, D. Zaridze, N. Szeszenia-Dabrowska, J. Lissowska, P. Rudnai, E. Fabianova, D. Mates, V. Bencko, L. Foretova, V. Janout, J.K. Field, T. Liloglou, G. Xinarianos, J. McLaughlin, G. Liu, F. Skorpen, M.B. Elvestad, K. Hveem, L. Vatten, E. Study, S. Benhamou, P. Lagiou, I. Holcatova, F. Merletti, K. Kjaerheim, A. Agudo, X. Castellsague, T.V. Macfarlane, L. Barzan, C. Canova, R. Lowry, D.I. Conway, A. Znaor, C. Healy, M.P. Curado, S. Koifman, J. Eluf-Neto, E. Matos, A. Menezes, L. Fernandez, A. Metspalu, S. Heath, M. Lathrop, and P. Brennan Association between a 15q25 gene variant, smoking quantity and tobacco-related cancers among 17 000 individuals Int. J. Epidemiol. 39 2010 563 577
30. J.Z. Liu, F. Tozzi, D.M. Waterworth, S.G. Pillai, P. Muglia, L. Middleton, W. Berrettini, C.W. Knouff, X. Yuan, G. Waeber, P. Vollenweider, M. Preisig, N.J. Wareham, J.H. Zhao, R.J.F. Loos, I. Barroso, K.T. Khaw, S. Grundy, P. Barter, R. Mahley, A. Kesaniemi, R. McPherson, J.B. Vincent, J. Strauss, J.L. Kennedy, A. Farmer, P. McGuffin, R. Day, K. Matthews, P. Bakke, A. Gulsvik, S. Lucae, M. Ising, T. Brueckl, S. Horstmann, H.E. Wichmann, R. Rawal, N. Dahmen, C. Lamina, O. Polasek, L. Zgaga, J. Huffman, S. Campbell, J. Kooner, J.C. Chambers, M.S. Burnett, J.M. Devaney, A.D. Pichard, K.M. Kent, L. Satler, J.M. Lindsay, R. Waksman, S. Epstein, J.F. Wilson, S.H. Wild, H. Campbell, V. Vitart, M.P. Reilly, M.Y. Li, L. Qu, R. Wilensky, W. Matthai, H.H. Hakonarson, D.J. Rader, A. Franke, M. Wittig, A. Schafer, M. Uda, A. Terracciano, X. Xiao, F. Busonero, P. Scheet, D. Schlessinger, D. St Clair, D. Rujescu, G.R. Abecasis, H.J. Grabe, A. Teumer, H. Volzke, A. Petersmann, U. John, I. Rudan, C. Hayward, A.F. Wright, I. Kolcic, B.J. Wright, J.R. Thompson, A.J. Balmforth, A.S. Hall, N.J. Samani, C.A. Anderson, T. Ahmad, C.G. Mathew, M. Parkes, J. Satsangi, M. Caulfield, P.B. Munroe, M. Farrall, A. Dominiczak, J. Worthington, W. Thomson, S. Eyre, A. Barton, V. Mooser, C. Francks, J. Marchini, and W.T.C.C. Consor Meta-analysis and imputation refines the association of 15q25 with smoking quantity Nat. Genet. 42 2010 436 440
31. A. McNeill, and M.R. Munafò Reducing harm from tobacco use J. Psychopharmacol. 27 2013 13 18
32. M.R. Munafò, and R. Araya Cigarette smoking and depression: a question of causation Br. J. Psychiatry 196 2010 425 426
33. M.R. Munafò, M.N. Timofeeva, R.W. Morris, D. Prieto-Merino, N. Sattar, P. Brennan, E.C. Johnstone, C. Relton, P.C. Johnson, D. Walther, P.H. Whincup, J.P. Casas, G.R. Uhl, P. Vineis, S. Padmanabhan, B.J. Jefferis, A. Amuzu, E. Riboli, M.N. Upton, P. Aveyard, S. Ebrahim, A.D. Hingorani, G. Watt, T.M. Palmer, N.J. Timpson, E.S. Group, and G. Davey Smith Association between genetic variants on chromosome 15q25 locus and objective measures of tobacco exposure J. Natl. Cancer Inst. 104 2012 740 748
34. B.G. Nordestgaard, T.M. Palmer, M. Benn, J. Zacho, A. Tybjaerg-Hansen, G. Davey Smith, and N.J. Timpson The effect of elevated body mass index on ischemic heart disease risk: causal estimates from a Mendelian randomisation approach PLoS Med. 9 2012 e1001212
35. B.L. Pierce, H. Ahsan, and T.J. Vanderweele Power and instrument strength requirements for Mendelian randomization studies using multiple genetic variants Int. J. Epidemiol. 40 2011 740 752
36. B.L. Pierce, and T.J. VanderWeele The effect of non-differential measurement error on bias, precision and power in Mendelian randomization studies Int. J. Epidemiol. 41 2012 1383 1393
37. J.A. Scott, J.A. Berkley, I. Mwangi, L. Ochola, S. Uyoga, A. Macharia, C. Ndila, B.S. Lowe, S. Mwarumba, E. Bauni, K. Marsh, and T.N. Williams Relation between falciparum malaria and bacteraemia in Kenyan children: a population-based, case-control study and a longitudinal study Lancet 378 2011 1316 1323
38. P.M. Sleiman, and S.F. Grant Mendelian randomization in the era of genomewide association studies Clin. Chem. 56 2010 723 728
39. J.H. Stock, J.H. Wright, and M. Yogo A survey of weak instruments and weak identification in generalized method of moments J. Bus. Econ. Stat. 20 2002 518 529
40. A.A. Strasser, C. Lerman, P.M. Sanborn, W.B. Pickworth, and E.A. Feldman New lower nicotine cigarettes can produce compensatory smoking and increased carbon monoxide exposure Drug Alcohol Depend. 86 2007 294 300
41. T.E. Thorgeirsson, F. Geller, P. Sulem, T. Rafnar, A. Wiste, K.P. Magnusson, A. Manolescu, G. Thorleifsson, H. Stefansson, A. Ingason, S.N. Stacey, J.T. Bergthorsson, S. Thorlacius, J. Gudmundsson, T. Jonsson, M. Jakobsdottir, J. Saemundsdottir, O. Olafsdottir, L.J. Gudmundsson, G. Bjornsdottir, K. Kristjansson, H. Skuladottir, H.J. Isaksson, T. Gudbjartsson, G.T. Jones, T. Mueller, A. Gottsater, A. Flex, K.K. Aben, F. de Vegt, P.F. Mulders, D. Isla, M.J. Vidal, L. Asin, B. Saez, L. Murillo, T. Blondal, H. Kolbeinsson, J.G. Stefansson, I. Hansdottir, V. Runarsdottir, R. Pola, B. Lindblad, A.M. van Rij, B. Dieplinger, M. Haltmayer, J.I. Mayordomo, L.A. Kiemeney, S.E. Matthiasson, H. Oskarsson, T. Tyrfingsson, D.F. Gudbjartsson, J.R. Gulcher, S. Jonsson, U. Thorsteinsdottir, A. Kong, and K. Stefansson A variant associated with nicotine dependence, lung cancer and peripheral arterial disease Nature 452 2008 638 642
42. N.J. Timpson, D.A. Lawlor, R.M. Harbord, T.R. Gaunt, I.N. Day, L.J. Palmer, A.T. Hattersley, S. Ebrahim, G.D. Lowe, A. Rumley, and G. Davey Smith C-reactive protein and its role in metabolic syndrome: Mendelian randomisation study Lancet 366 2005 1954 1959
43. J. Tyrrell, V. Huikari, J.T. Christie, A. Cavadino, R. Bakker, M.J. Brion, F. Geller, L. Paternoster, R. Myhre, C. Potter, P.C. Johnson, S. Ebrahim, B. Feenstra, A.L. Hartikainen, A.T. Hattersley, A. Hofman, M. Kaakinen, L.P. Lowe, P. Magnus, A. McConnachie, M. Melbye, J.W. Ng, E.A. Nohr, C. Power, S.M. Ring, S.P. Sebert, V. Sengpiel, H.R. Taal, G.C. Watt, N. Sattar, C.L. Relton, B. Jacobsson, T.M. Frayling, T.I. Sorensen, J.C. Murray, D.A. Lawlor, C.E. Pennell, V.W. Jaddoe, E. Hypponen, W.L. Lowe Jr.; M.R. Jarvelin, G. Davey Smith, R.M. Freathy, and Early Growth Genetics Consortium Genetic variation in the 15q25 nicotinic acetylcholine receptor gene cluster (CHRNA5-CHRNA3-CHRNB4) interacts with maternal self-reported smoking status during pregnancy to influence birth weight Hum. Mol. Genet. 21 2012 5344 5358
44. B.F. Voight, G.M. Peloso, M. Orho-Melander, R. Frikke-Schmidt, M. Barbalic, M.K. Jensen, G. Hindy, H. Holm, E.L. Ding, T. Johnson, H. Schunkert, N.J. Samani, R. Clarke, J.C. Hopewell, J.F. Thompson, M. Li, G. Thorleifsson, C. Newton-Cheh, K. Musunuru, J.P. Pirruccello, D. Saleheen, L. Chen, A. Stewart, A. Schillert, U. Thorsteinsdottir, G. Thorgeirsson, S. Anand, J.C. Engert, T. Morgan, J. Spertus, M. Stoll, K. Berger, N. Martinelli, D. Girelli, P.P. McKeown, C.C. Patterson, S.E. Epstein, J. Devaney, M.S. Burnett, V. Mooser, S. Ripatti, I. Surakka, M.S. Nieminen, J. Sinisalo, M.L. Lokki, M. Perola, A. Havulinna, U. de Faire, B. Gigante, E. Ingelsson, T. Zeller, P. Wild, P.I. de Bakker, O.H. Klungel, A.H. Maitland-van der Zee, B.J. Peters, A. de Boer, D.E. Grobbee, P.W. Kamphuisen, V.H. Deneer, C.C. Elbers, N.C. Onland-Moret, M.H. Hofker, C. Wijmenga, W.M. Verschuren, J.M. Boer, Y.T. van der Schouw, A. Rasheed, P. Frossard, S. Demissie, C. Willer, R. Do, J.M. Ordovas, G.R. Abecasis, M. Boehnke, K.L. Mohlke, M.J. Daly, C. Guiducci, N.P. Burtt, A. Surti, E. Gonzalez, S. Purcell, S. Gabriel, J. Marrugat, J. Peden, J. Erdmann, P. Diemert, C. Willenborg, I.R. Konig, M. Fischer, C. Hengstenberg, A. Ziegler, I. Buysschaert, D. Lambrechts, F. Van de Werf, K.A. Fox, N.E. El Mokhtari, D. Rubin, J. Schrezenmeir, S. Schreiber, A. Schafer, J. Danesh, S. Blankenberg, R. Roberts, R. McPherson, H. Watkins, A.S. Hall, K. Overvad, E. Rimm, E. Boerwinkle, A. Tybjaerg-Hansen, L.A. Cupples, M.P. Reilly, O. Melander, P.M. Mannucci, D. Ardissino, D. Siscovick, R. Elosua, K. Stefansson, C.J. O'Donnell, V. Salomaa, D.J. Rader, L. Peltonen, S.M. Schwartz, D. Altshuler, and S. Kathiresan Plasma HDL cholesterol and risk of myocardial infarction: a Mendelian randomisation study Lancet 380 2012 572 580
45. J. Wang, M.R. Spitz, C.I. Amos, A.V. Wilkinson, X. Wu, and S. Shete Mediating effects of smoking and chronic obstructive pulmonary disease on the relation between the CHRNA5-A3 genetic locus and lung cancer risk Cancer 116 2010 3458 3462
46. T.J. Wang, F. Zhang, J.B. Richards, B. Kestenbaum, J.B. van Meurs, D. Berry, D.P. Kiel, E.A. Streeten, C. Ohlsson, D.L. Koller, L. Peltonen, J.D. Cooper, P.F. O'Reilly, D.K. Houston, N.L. Glazer, L. Vandenput, M. Peacock, J. Shi, F. Rivadeneira, M.I. McCarthy, P. Anneli, I.H. de Boer, M. Mangino, B. Kato, D.J. Smyth, S.L. Booth, P.F. Jacques, G.L. Burke, M. Goodarzi, C.L. Cheung, M. Wolf, K. Rice, D. Goltzman, N. Hidiroglou, M. Ladouceur, N.J. Wareham, L.J. Hocking, D. Hart, N.K. Arden, C. Cooper, S. Malik, W.D. Fraser, A.L. Hartikainen, G. Zhai, H.M. Macdonald, N.G. Forouhi, R.J. Loos, D.M. Reid, A. Hakim, E. Dennison, Y. Liu, C. Power, H.E. Stevens, L. Jaana, R.S. Vasan, N. Soranzo, J. Bojunga, B.M. Psaty, M. Lorentzon, T. Foroud, T.B. Harris, A. Hofman, J.O. Jansson, J.A. Cauley, A.G. Uitterlinden, Q. Gibson, M.R. Jarvelin, D. Karasik, D.S. Siscovick, M.J. Econs, S.B. Kritchevsky, J.C. Florez, J.A. Todd, J. Dupuis, E. Hypponen, and T.D. Spector Common genetic determinants of vitamin D insufficiency: a genome-wide association study Lancet 376 2010 180 188
47. J.J. Ware, M.B. van den Bree, and M.R. Munafò Association of the CHRNA5-A3-B4 gene cluster with heaviness of smoking: a meta-analysis Nicotine Tob. Res. 13 2011 1167 1175
48. G. Wehby, A. Jugessur, J.C. Murray, L. Moreno, A. Wilcox, and R.T. Lie Genes as instruments for studying risk behaviour effects: an application to maternal smoking and orofacial clefts Health Serv. Outcomes Res. Methodol. 11 2011 54 78
49. G.L. Wehby, J.M. Fletcher, S.F. Lehrer, L.M. Moreno, J.C. Murray, A. Wilcox, and R.T. Lie A genetic instrumental variables analysis of the effects of prenatal smoking on birth weight: evidence from two samples Biodemography Soc. Biol. 57 2011 3 32
50. G.L. Wehby, J.C. Murray, A. Wilcox, and R.T. Lie Smoking and body weight: evidence using genetic instruments Econ. Hum. Biol. 10 2012 113 126
51. G.L. Wehby, R.L. Ohsfeldt, and J.C. Murray 'Mendelian randomization' equals instrumental variable analysis with genetic instruments Stat. Med. 27 2008 2745 2749