Construction of gene clusters resembling genetic causal mechanisms for common complex disease with an application to young-onset hypertension

Age of Hypertension Onset: Overview of Research and How to Apply in Practice

PURPOSE OF REVIEW

To review the current evidence on research related to age of hypertension onset-its definition, correlates, heritability, and association with adverse outcomes. We also propose a framework for implementing assessment of hypertension onset age into clinical practice.

RECENT FINDINGS

Prior studies have used both objective measurements and self-report to determine age of hypertension onset or early-onset hypertension. Yet, no criterion for standard definition currently exists for either. Data from epidemiological and clinical studies demonstrate that early-onset hypertension is a highly heritable trait that confers an increased risk for cardiovascular death and end-organ damage compared with late-onset hypertension. Literature to date suggests that (parental) age of hypertension onset can be feasibly assessed for estimating (1) risk of future hypertension in non-hypertensive persons; and (2) the propensity for cardiovascular disease in individuals with established hypertension.

Early Onset Hypertension Is Associated With Hypertensive End-Organ Damage Already by MidLife

Early onset hypertension confers increased risk for cardiovascular mortality in the community. Whether early onset hypertension also promotes the development of target end-organ damage (TOD), even by midlife, has remained unknown. We studied 2680 middle-aged CARDIA study (Coronary Artery Risk Development in Young Adults) Study participants (mean age 50±4 years, 57% women) who underwent up to 8 serial blood pressure measurements between 1985 and 2011 (age range at baseline 18-30 years) in addition to assessments of echocardiographic left ventricular hypertrophy, coronary calcification, albuminuria, and diastolic dysfunction in 2010 to 2011. Age of hypertension onset was defined as the age at first of 2 consecutively attended examinations with blood pressure ≥140/90 mm Hg or use of antihypertensive medication. Participants were divided in groups by hypertension onset age (<35 years, 35-44 years, ≥45 years, or no hypertension). While adjusting for TOD risk factors, including systolic blood pressure, we used logistic regression to calculate odds ratios for cases (participants with TOD) versus controls (participants without TOD) to examine the relation of hypertension onset age and hypertensive TOD. Compared with normotensive individuals, hypertension onset at age <35 years was related to odds ratios of 2.29 (95% CI, 1.36-3.86), 2.94 (95% CI, 1.57-5.49), 1.12 (95% CI, 0.55-2.29), and 2.06 (95% CI, 1.04-4.05) for left ventricular hypertrophy, coronary calcification, albuminuria, and diastolic dysfunction, respectively. In contrast, hypertension onset at age ≥45 years was not related to increased odds of TOD. Our findings emphasize the importance of assessing age of hypertension onset in hypertensive patients to identify high-risk individuals for preventing hypertensive complications.

Incorporation of protein binding effects into likelihood ratio test for exome sequencing data

Statistical association studies are an important tool in detecting novel disease genes. However, for sequencing data, association studies confront the challenge of low power because of relatively small data sample size and rare variants. Incorporating biological information that reflects disease mechanism is likely to strengthen the association evidence of disease genes, and thus increase the power of association studies. In this paper, we annotate non-synonymous single-nucleotide variants according to protein binding sites (BSs) by using a more accurate BS prediction method. We then incorporate this information into association study through a statistical framework of likelihood ratio test (LRT) based on weighted burden score of single-nucleotide variants (SNVs). The strategy is applied to Genetic Analysis Workshop 19 exome-sequencing data for detecting novel genes associated to hypotension. The SNV-weighting LRT idea is empirically verified by the simulated phenotypes (336 cases and 1607 controls), and the weights based on BS annotation are applied to the real phenotypes (394 cases and 1457 controls). Such strategy of weighting the prior information on protein functional sites is shown to be superior to the unweighted LRT and serves as a good complement to the existing association tests. Several putative genes are reported; some of them are functionally related to hypertension according to the previous evidence in the literature.

A literature mining-based approach for identification of cellular pathways associated with chemoresistance in cancer

Chemoresistance is a major obstacle to the successful treatment of many human cancer types. Increasing evidence has revealed that chemoresistance involves many genes and multiple complex biological mechanisms including cancer stem cells, drug efflux mechanism, autophagy and epithelial-mesenchymal transition. Many studies have been conducted to investigate the possible molecular mechanisms of chemoresistance. However, understanding of the biological mechanisms in chemoresistance still remains limited. We surveyed the literature on chemoresistance-related genes and pathways of multiple cancer types. We then used a curated pathway database to investigate significant chemoresistance-related biological pathways. In addition, to investigate the importance of chemoresistance-related markers in protein-protein interaction networks identified using the curated database, we used a gene-ranking algorithm designed based on a graph-based scoring function in our previous study. Our comprehensive survey and analysis provide a systems biology-based overview of the underlying mechanisms of chemoresistance.