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.
Bibliographical noteFunding Information:
This research was supported by a grant from the National Institute on Aging ( P01 AG020166 ). The original MIDUS study was supported by the MacArthur Foundation Research Network on Successful Midlife Development. Specimen collection was facilitated by the General Clinical Research Centers program ( M01-RR023942 [Georgetown], M01-RR00865 [UCLA]), and at UW from the Clinical and Translational Science Award ( CTSA ) program of the National Center for Research Resources (1UL1RR025011). The contributions of D. Brar and J. Wochos are gratefully acknowledged. WZA is a predoctoral fellow on a NIMH supported training program (5T32 MH018931).
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Copyright 2015 Elsevier B.V., All rights reserved.
- C-reactive protein
- Soluble interleukin-6 receptor