Investigating Overlapping Genetic Factors and Novel Causal Genes in Autoimmune Diseases: A Transcriptome-Wide...

Area of Science:

• Immunogenetics
• Genomics
• Molecular Biology

Background:

• Autoimmune diseases show familial clustering, indicating shared genetic underpinnings.
• Previous research has not fully elucidated the overlapping genetic factors across various autoimmune conditions.
• This study focuses on identifying common genetic risks among systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), ankylosing spondylitis (AS), Sjögren's syndrome (SS), and polymyalgia rheumatica (PMR).

Purpose of the Study:

• To identify shared genetic factors across five distinct autoimmune diseases.
• To pinpoint specific genes and variants contributing to the co-occurrence of these conditions.
• To investigate the functional significance of identified shared genes, particularly in the context of SLE.

Main Methods:

• Transcriptome-wide association study (TWAS) in blood tissue to identify candidate genes.
• Bayesian colocalization and Multiomics summary data-based Mendelian randomization (SMR) analyses to detect shared variants and causal risk genes.
• Transcriptomic analysis, gene set variation analysis (GSVA), and weighted gene coexpression network analysis (WGCNA) for functional investigation.

Main Results:

• TWAS identified 78 candidate genes across the five autoimmune diseases.
• Five genes (GTF2H4, FLOT1, HCP5, IER3, STK19) showed shared genetic variants across diseases.
• FLOT1 was highlighted as a causal risk gene for SLE, highly expressed in T cells and platelets, and associated with metabolic pathways.

Conclusions:

• This research reveals shared genetic factors contributing to the development of multiple autoimmune diseases.
• FLOT1 emerges as a novel causal risk gene for SLE, implicating platelet-related mechanisms.
• The findings offer potential new therapeutic targets for SLE by focusing on platelet-mediated pathways.