Human genome epidemiology （HUGE） uses sys- tematic applications of epidemiologic methods to as- sess the impact of human genetic variation on health and disease. In the past ten years, human genome epi- demiology has made great progresses along with ad- vances in genomics technologies, which make it pos- sible for the examination of genetic variants in a large sample size at a sufficiently low cost. Genetic associa- tion study in population provides a powerful approach to identify variants or genes associated with disease of interest by comparing distributions of genetic variants between affected and unaffected individuals.
Runs of homozygosity （ROHs） are a class of important but poorly studied genomic variations and may be in- volved in individual susceptibility to diseases. To better understand ROH and its relationship with lung cancer, we performed a genome-wide ROH analysis of a subset of a previous genome-wide case-control study （1,473 cases and 1,962 controls） in a Han Chinese population. ROHs were classified into two classes, based on lengths, intermedi- ate and long ROils, to evaluate their association with lung cancer risk using existing genome-wide single nucleofide polymorphism （SNP） data. We found that the overall level of intermediate ROHs was significantly associated with a decreased risk of lung cancer （odds ratio = 0.63; 95% confidence interval： 0.51-0.77; P = 4.78 × 10-6 ）, while the long ROHs seemed to be a risk factor of lung cancer. We also identified one ROH region at 14q23A that was con- sistently associated with lung cancer risk in the study. These results indicated that ROHs may be a new class of variation which may be associated with lung cancer risk, and genetic variants at 14q23.1 may be involved in the development of lung cancer.
Telomeres play a critical role in biological ageing by maintaining chromosomal integrity and preventing chromosome ends fusion. Epidemiological studies have suggested that inter-individual differences of telomere length could affect predisposition to multiple cancers, but evidence regarding esophageal squamous cell carcinoma （ESCC） was still uncertain. Several telomere length-related single nucleotide polymorphisms （TL- SNPs） in Caucasians have been reported in genome-wide association studies. However, the effects of telomere length and TL-SNPs on ESCC development are unclear. Therefore, we conducted a case-control study （1045 ESCC cases and 1433 controls） to evaluate the associations between telomere length, TL-SNPs, and ESCC risk in Chinese population. As a result, ESCC cases showed overall shorter relative telomere length （RTL） （median： 1.34） than controls （median： 1.50, P 〈 0.001）. More interestingly, an evident nonlinear U-shaped association was observed between RTL and ESCC risk （P 〈 0.001）, with odds ratios （95% confidence interval） equal to 2.40 （1.84- 3.14）, 1.36 （1.03-1.79）, 1.01 （0.76-1.35）, and 1.37 （1.03-1.82） for individuals in the 1st （the shortest）, 2nd, 3rd, and 5th （the longest） quintile, respectively, compared with those in the 4th quintile as reference group. No significant associations were observed between the eight reported TL-SNPs and ESCC susceptibility. These findings suggest that either short or extremely long telomeres may be risk factors for ESCC in the Chinese population.
