title: Genetic and environmental determinants of population variation in interleukin-6, its soluble receptor and C-reactive protein: insights from identical and fraternal twins.
abstract: Interleukin-6 and C-reactive protein are commonly assessed biomarkers linked to illness, obesity, and stressful life events. However, relatively little is known about their heritability. By comparing Caucasian twins from the Midlife in the US project (MIDUS), we estimated the heritability of IL-6, its soluble receptor, and CRP. Based on the hypothesis that adiposity might contribute more to IL-6 than to sIL-6r, we fit heritability models quantifying the extent to which each reflected genetic and environmental factors shared with obesity. Genetic influences on IL-6 and its receptor proved to be distinct. Further, the appearance of a heritable basis for IL-6 was mediated largely via shared paths with obesity. Supporting this conclusion, we confirmed that when unrelated adult controls are carefully matched to twin participants on BMI, age, gender and socioeconomic indices, their IL-6 is similar to the corresponding twins. In contrast, the effect of BMI on CRP was split between shared genetics and environmental influences. In conclusion, IL-6 is strongly affected by factors associated with obesity accounting for its lability and responsiveness to diet, life style and contemporaneous events.
authors.affiliation: Department of Psychology, University of Wisconsin-Madison, Madison, WI 53715, USA.
authors.forename: Wellington Z
authors.initials: WZ
authors.lastname: Amaral
authors.affiliation: Department of Psychology, University of Minnesota, Minneapolis, MN 55455, USA. Electronic address: krueg038@umn.edu.
authors.forename: Robert F
authors.initials: RF
authors.lastname: Krueger
authors.affiliation: Department of Psychology, University of Wisconsin-Madison, Madison, WI 53715, USA. Electronic address: cryff@wisc.edu.
authors.forename: Carol D
authors.initials: CD
authors.lastname: Ryff
authors.affiliation: Department of Psychology, University of Wisconsin-Madison, Madison, WI 53715, USA. Electronic address: ccoe@wisc.edu.
authors.forename: Christopher L
authors.initials: CL
authors.lastname: Coe
mesh_terms: D015992:Body Mass Index; D002097:C-Reactive Protein / Q000235:genetics*; D005260:Female; D059647:Gene-Environment Interaction; D006801:Humans; D015850:Interleukin-6 / Q000235:genetics*; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000235:genetics*; D019947:Receptors, Interleukin-6 / Q000235:genetics*; D014427:Twins; D014481:United States / Q000208:ethnology; D044465:White People
chemical_list: D015850:Interleukin-6; D019947:Receptors, Interleukin-6; D002097:C-Reactive Protein
keywords: C-reactive protein; Heritability; Interleukin-6; Obesity; Soluble interleukin-6 receptor; Twins