Role of SIRPG gene in type 1 diabetes and lichen planus

Type 1 diabetes (T1D) is a form of diabetes caused by pancreatic β-cell destruction and absolute insulin deficiency. Lichen planus (LP) is an idiopathic inflammatory skin disease of unclear etiology. The role of SIRPG gene dysregulation in T1D and LP remains unclear. Mendelian randomization (MR) using matched samples was employed to study causal relationship between T1D and increased risk of LP. T1D-related single nucleotide polymorphism identification was conducted. Datasets GSE156035 for T1D and GSE52130 for LP were obtained from gene expression omnibus. Differentially expressed genes were identified, analyses included weighted gene co-expression network analysis, functional enrichment, gene set enrichment analysis, and protein-protein interaction network construction and analysis. Heatmaps of gene expression levels were generated. Comparative toxicogenomics database was used to identify diseases most relevant to core genes. Inverse variance weighted, MR-Egger, weighted median methods estimated genetic predisposition between T1D and LP, showing consistent positive correlations using both weighted median and inverse variance weighted methods. Horizontal pleiotropy analysis with MR-Egger intercept indicated no evidence of significant directional pleiotropy (P = .70645) for LP. There was no evidence of directional pleiotropy effects between T1D and LP. One hundred eighteen differentially expressed genes were identified. In biological processes, they were mainly enriched in apoptosis, inflammatory response, insulin receptor signaling pathway, glucose metabolism. In cellular components, enrichment was observed in mediator complex and replication fork. In molecular function, they were concentrated in leukotriene receptor activity and helicase activity. Kyoto Encyclopedia of Genes and Genomes analysis revealed enrichment in metabolic pathways, PI3K-Akt signaling pathway, cell cycle, p53 signaling pathway, AGE-RAGE signaling pathway in diabetic complications. Weighted gene co-expression network analysis with a soft threshold power of 4. SIRPG showing high expression in both T1D and LP samples. There is a positive causal relationship between T1D and LP. Comparative toxicogenomics database analysis revealed associations of core genes with metabolic syndrome, lipid metabolism disorders, cardiovascular diseases, immune system diseases, peripheral neuropathic pain, and inflammation. SIRPG is highly expressed in both T1D and LP, providing a new insight into the pathogenesis of T1D and LP.