TY - JOUR T1 - Telomere length and health outcomes: A two-sample genetic instrumental variables analysis. JF - Exp Gerontol Y1 - 2016 A1 - Hamad, Rita A1 - Stefan Walter A1 - David Rehkopf KW - Aged KW - Aging KW - Coronary Artery Disease KW - Databases, Factual KW - Female KW - Humans KW - Longitudinal Studies KW - Male KW - Middle Aged KW - Molecular Epidemiology KW - Polymorphism, Single Nucleotide KW - Self Report KW - Telomere KW - Telomere Homeostasis KW - United States AB -

OBJECTIVE: Previous studies linking telomere length (TL) and health have been largely associational. We apply genetic instrumental variables (IV) analysis, also known as Mendelian randomization, to test the hypothesis that shorter TL leads to poorer health. This method reduces bias from reverse causation or confounding.

METHODS: We used two approaches in this study that rely on two separate data sources: (1) individual-level data from the Health and Retirement Study (HRS) (N=3734), and (2) coefficients from genome-wide association studies (GWAS). We employed two-sample genetic IV analyses, constructing a polygenic risk score (PRS) of TL-associated single nucleotide polymorphisms. The first approach examined the association of the PRS with nine individual health outcomes in HRS. The second approach took advantage of estimates available in GWAS databases to estimate the impact of TL on five health outcomes using an inverse variance-weighted meta-analytic technique.

RESULTS: Using individual-level data, shorter TL was marginally statistically significantly associated with decreased risk of stroke and increased risk of heart disease. Using the meta-analytic approach, shorter TL was associated with increased risk of coronary artery disease (OR 1.02 per 100 base pairs, 95%CI: 1.00, 1.03).

DISCUSSION: With the exception of a small contribution to heart disease, our findings suggest that TL may be a marker of disease rather than a cause. They also demonstrate the utility of the inverse variance-weighted meta-analytic approach when examining small effect sizes.

VL - 82 UR - http://www.ncbi.nlm.nih.gov/pubmed/27321645 U1 - http://www.ncbi.nlm.nih.gov/pubmed/27321645?dopt=Abstract ER -