Sas AA, et al. – In this current study, researchers used a longitudinal classical twin design to scrutinize the stability and relative effect of genetic and environmental factors underlying serum levels of C-reactive Protein (CRP). They obtained proof for stable heritability estimates of CRP of around 50% with advancing age. However, the reported between–visit genetic correlations were markedly lower than 1, suggesting the emergence of new genetic impacts on CRP levels with age.

Methods

• This study included a maximum of 6201 female twins from the TwinsUK registry with up to three CRP measurements (i.e. visit 1 [V1], visit 2 [V2] and visit 3 [V3]) over a 10-year follow-up period.
• Researchers applied structural equation modeling to dissect the observed phenotypic variance into its genetic and environ-mental components.
• They used a trivariate model to estimate the heritability of CRP as well as its genetic and environmental correlations across different time points.

Results

• Findings demonstrated that natural log (ln) CRP levels significantly increased from V1 to V2 (p=4.4 × 10^-25) and between V1 and V3 (p=1.2 × 10^-15), but not between V2 and V3.
• Data showed that the median (IQR) follow-up time between V1 and V3 was 9.58 (8.00–10.46) years.
• Researches observed that heritability estimates for CRP were around 50% and constant over time (0.46–0.52).
• Additionally, they noted that adjustment for BMI did not meaningfully change the heritability estimates (0.49–0.51).
• The outcomes also highlighted that the genetic correlations between visits were significantly smaller than one, ranging from 0.66 to 0.85.