Single-Locus, Interaction, and Functional Pathway Analyses of Acne Severity in a 60-SNP Panel

Acne vulgaris is a multifactorial disease with high heritability, but the genetic determinants of severity remain incompletely defined. This study evaluated 650 individuals genotyped with a 60-single-nucleotide polymorphism (SNP) panel covering immune, lipid, endocrine, and barrier pathways. Acne severity was graded as 1 (n = 193), 2–3 (n = 383), or 4 (n = 74). Single-SNP analysis highlighted associations in loci such as LHCGR (rs13405728), TGF-β2 (rs1159268), FST (rs38055), WNT10A (rs74333950), PIK3R1 (rs10515088), and THADA (rs13429458) and barrier-related variants (FLG, FLG-AS1). Epistasis analysis of 44 quality-controlled SNPs revealed 190 significant interactions (false discovery rate, FDR ≤ 0.10), with TLR4 as the main hub (degree = 22), bridging immune (IL10, TNF), lipid (PNPLA3, APOE), and barrier (FLG-AS1, OVOL1) genes. Polygenic risk scoring (PRS) showed a monotonic increase across severity grades, with Grade 4 displaying higher median scores (0.319) compared to Grade 1 (−0.129) and Grades 2–3 (0.034). Discrimination was modest but consistent (AUC: 0.661 for Grade 4 vs. 1; 0.662 vs. 2–3; 0.679 vs. all others). These results support a framework where microbial sensing, lipid metabolism, and barrier function converge to drive severe acne, underscoring the potential of genetic profiling for risk stratification and precision therapy.