Biology subjects

Ghasemi, E.

Publications and source records attributed to Ghasemi, E..

3 recordsLinked to original sources

bioRxiv2026

A genome-wide catalog of sites where peripheral DNA methylation reflects the brain

Epigenetic studies of psychiatric and neurological disorders rely largely on peripheral tissues, yet where peripheral DNA methylation (DNAm) reflects the brain remains unclear. We generated a paired brain and peripheral DNAm dataset from 148 donors in three cohorts and combined it with five published cohorts for consensus brain-peripheral correlations. By cross-validation across cohorts, we defined brain epigenome shared sites (BrESS), more than 100,000 CpGs per tissue at which peripheral DNAm reproducibly predicts brain DNAm. BrESS lay at promoters active in both brain and periphery and in housekeeping genes, and most were not explained by genetic effects. BrESS did not contribute to the heritability of seven disorders, and CpGs from epigenome-wide association studies of these disorders were not enriched at BrESS. Peripheral DNAm reflects the brain mainly in a regulatory compartment shared across tissues, outside which disease signals largely lie, and BrESS separate peripheral signals attributable to the brain from others.

neuroscience↗

bioRxiv2026

Predicting Clinical Phenotypes by Growth Curve Modeling of Transcriptomic Signatures during Disease Progression

High-throughput transcriptomic analysis has benefited from many statistical tests of differential gene expression across two or more groups such as t tests, ANOVA, etc. Yet, in complex transcriptomic datasets such as multi-group longitudinal measures, few studies have addressed such key issues as group effects and temporal dependency in expression profiles with a single model that is both practically effective and theoretically grounded. In this study, we used Growth Curve Model (GCM), as a generalization of MANOVA, to identify differentially expressed longitudinal profiles of genes, and thus predicted the associated clinical phenotypes, of pediatric lupus during the progressions of the disease across two different racial groups. In particular, we detected a module of histone genes which was shown to be linked with lupus.

bioinformatics↗

bioRxiv2025

Stability and Performance of Linear Combination Tests of Gene Set Enrichment for Multiple Covariance Estimators in Unbalanced Studies

Gene set analysis (GSA) is essential for understanding coordinated gene expression changes within biological pathways, especially in high-dimensional data generated by platforms such as RNA-seq and microarrays. This study focuses on the linear combination test (LCT), a GSA method that combines multiple genelevel statistics into a powerful test statistic to assess the association between a gene set and outcomes of interest in a given set of samples. We evaluated the performance and stability of LCT using different covariance matrix estimators, including ridge, graphical lasso, and adaptive lasso, which are known for their effectiveness in high-dimensional data analysis. In addition, we assessed the robustness of LCT in the face of unbalanced study designs, which are typical in biomedical research due to limited sample availability and the high cost of data generation. We conducted a simulation study and applied LCT to publicly available gene expression datasets comparing patients with systemic lupus erythematosus (SLE) to healthy controls, where the number of controls is significantly lower than the number of cases. Our findings demonstrate that while LCTs default shrinkage estimator shows limitations in highly correlated and unbalanced designs, ridge estimation provides a more reliable alternative for unbalanced scenarios. Researchers can optimize LCTs performance by selecting appropriate covariance estimators based on their data structure. These results suggest that LCT is a reliable and powerful tool for GSA in unbalanced studies, identifying SLE-relevant gene sets more effectively than other GSA methods and showing validation against clinical phenotypes, offering valuable insights into the underlying mechanisms of complex diseases such as SLE.

bioinformatics↗