Association Between Telomere Length and Risk of Cancer and Non-Neoplastic Diseases: A Mendelian Randomization Study.

Area of Science:

• Genetics
• Oncology
• Epidemiology

Background:

• The relationship between telomere length and disease incidence is unclear due to observational study limitations like confounding and reverse causation.
• Telomeres, protective caps on chromosomes, shorten with cell division and are implicated in aging and disease.

Purpose of the Study:

• To investigate the causal effect of telomere length on the risk of developing various cancers and non-neoplastic diseases.
• Utilize Mendelian randomization with germline genetic variants as instrumental variables to assess causality.

Main Methods:

• Conducted a Mendelian randomization study using summary statistics from genomewide association studies (GWAS) published up to January 15, 2015.
• Included 103 GWAS of noncommunicable diseases, analyzing genetic variants associated with telomere length.
• Calculated odds ratios (ORs) and 95% confidence intervals (CIs) for disease risk per standard deviation (SD) increase in genetically determined telomere length.

Main Results:

• Genetically determined longer telomere length was associated with an increased risk for several site-specific cancers, including glioma, ovarian, lung, and neuroblastoma.
• Associations between longer telomeres and cancer risk were stronger for rarer cancers and tissues with lower stem cell division rates.
• Limited evidence of association was found for most non-neoplastic diseases, with exceptions including reduced risk for coronary heart disease, abdominal aortic aneurysm, celiac disease, and interstitial lung disease.

Conclusions:

• Longer telomere length is likely a causal factor increasing the risk for several types of cancer.
• Conversely, longer telomeres may confer a protective effect against certain non-neoplastic diseases, notably cardiovascular conditions.
• This study provides robust evidence for the causal role of telomere length in disease etiology.