Targeted Resequencing and Functional Testing Identifies Low-Frequency Missense Variants in the Gene Encoding GARP as Significant Contributors to Atopic Dermatitis Risk

• Published in: Journal of investigative dermatology Vol. 136; no. 12; pp. 2380 - 2386
• Main Authors: Manz, Judith, Rodríguez, Elke, ElSharawy, Abdou, Oesau, Eva-Maria, Petersen, Britt-Sabina, Baurecht, Hansjörg, Mayr, Gabriele, Weber, Susanne, Harder, Jürgen, Reischl, Eva, Schwarz, Agatha, Novak, Natalija, Franke, Andre, Weidinger, Stephan
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.12.2016
• Subjects: Adult; Case-Control Studies; Cells, Cultured; Chromosome Mapping; Dermatitis, Atopic - drug therapy; Dermatitis, Atopic - genetics; Dermatitis, Atopic - pathology; Disease Progression; Female; Gene Expression Regulation; Genetic Predisposition to Disease; Genotype; Humans; Immunohistochemistry; Male; Membrane Proteins - genetics; Molecular Sequence Data; Mutation, Missense; Prognosis; Real-Time Polymerase Chain Reaction; Risk Assessment; RNA, Messenger - analysis; RNA, Messenger - genetics; Sequence Deletion; T-Lymphocytes, Regulatory - immunology; T-Lymphocytes, Regulatory - pathology; PBS; C11orf30; AD; Treg; GARP; TGF-β; LAP; SNV; LRRC32; WT
• ISSN: 0022-202X; 1523-1747; 1523-1747
• DOI: 10.1016/j.jid.2016.07.009

Gene-mapping studies have consistently identified a susceptibility locus for atopic dermatitis and other inflammatory diseases on chromosome band 11q13.5, with the strongest association observed for a common variant located in an intergenic region between the two annotated genes C11orf30 and LRRC32. Using a targeted resequencing approach we identified low-frequency and rare missense mutations within the LRRC32 gene encoding the protein GARP, a receptor on activated regulatory T cells that binds latent transforming growth factor-β. Subsequent association testing in more than 2,000 atopic dermatitis patients and 2,000 control subjects showed a significant excess of these LRRC32 variants in individuals with atopic dermatitis. Structural protein modeling and bioinformatic analysis predicted a disruption of protein transport upon these variants, and overexpression assays in CD4+CD25– T cells showed a significant reduction in surface expression of the mutated protein. Consistently, flow cytometric (FACS) analyses of different T-cell subtypes obtained from atopic dermatitis patients showed a significantly reduced surface expression of GARP and a reduced conversion of CD4+CD25– T cells into regulatory T cells, along with lower expression of latency-associated protein upon stimulation in carriers of the LRRC32 A407T variant. These results link inherited disturbances of transforming growth factor-β signaling with atopic dermatitis risk.