Identifying Genetic and Environmental influences on C-reactive Protein and Its correlation with Metabolic Syndrome: The Healthy Twin Study

Abstract

Recently, studies have reported that many chronic complex diseases are closely related to other diseases. For instance, Type 2 Diabetes, Metabolic Syndrome, and Cardiovascular diseases share causes and symptoms in a large proportion. Moreover C-reactive protein(CRP) has also been reported as an associated factor for various kinds of such chronic diseases. Originally, CRP was known as an acute phase inflammation marker. However, after a highly sensitive measurement has been developed, base-line serum CRP concentration has been used as a risk marker when predicting future Cardiovascular diseases. This study aims to confirm the association between CRP concentration and Metabolic Syndrome related characteristics and to identify genetic and environmental contributions to the CRP level. A total of 2,890 individuals participated in the current study. This number included 640 families, 430 Monozygotic(MZ) Twins, and 97 Dizygotic(DZ) Twins in order to figure out the genetic and environmental contributions to the CRP concentration. To examine the strong association between CRP concentration and Metabolic Syndrome(MetS), different distributions of CRP concentration according to the 5 diagnostic criteria suggested by NCEP and correlations between CRP concentration and MetS related factors were examined. To quantify the life style effect on the CRP concentration, regression and logistic regression analyses using mixed model were conducted. By using variance component model, Intraclass correlation coefficients and heritability were estimated. The results showed a strong association between the CRP concentration and MetS related factors, as expected. Also, abdominal obesity was found to be the most relevant index for predicting the CRP concentration among other obesity indices. Along with abdominal obesity, income level showed a close relationship with CRP concentration. The result of Intraclass correlation coeffecients (ICC) and heritability estimates suggest a large proportion of genetic contributions as well as shared environmental contributions to the CRP. Accordingly, obesity, especially abdominal obesity should be given more attention to prevent CRP elevation and other CRP related diseases. When the exact genes regulating CRP concentration are found, it might be possible to apply it to an intervention strategy considering genetic information.