Knowledge-based analysis of genetic associations of rheumatoid arthritis to inform studies searching for pleiotropic genes: a literature review and network analysis
ARTHRITIS RESEARCH & THERAPY
Authors: Zheng, Weiying; Rao, Shaoqi
Abstract
Introduction: Pleiotropy describes the genetic effect of a single gene on multiple phenotypic traits. Gene variants directly affect the normal processes of a series of physiological and biochemical reactions, and therefore cause a variety of diseases traits to be changed accordingly. Moreover, a shared genetic susceptibility mechanism may exist between different diseases. Therefore, shared genes, with pleiotropic effects, are important to understand the sharing pathogenesis and hence the mechanisms underlying comorbidity. Methods: In this study, we proposed combining genome-wide association studies (GWAS) and public knowledge databases to search for potential pleiotropic genes associated with rheumatoid arthritis (RA) and eight other related diseases. Here, a GWAS-based network analysis is used to recognize risk genes significantly associated with RA. These RA risk genes are re-extracted as potential pleiotropic genes if they have been proved to be susceptible genes for at least one of eight other diseases in the OMIM or PubMed databases. Results: In total, we extracted 116 potential functional pleiotropic genes for RA and eight other diseases, including five hub pleiotropic genes, BTNL2, HLA-DRA, NOTCH4, TNXB, and C6orf10, where BTNL2, NOTCH4, and C6orf10 are novel pleiotropic genes identified by our analysis. Conclusions: This study demonstrates that pleiotropy is a common property of genes associated with disease traits. Our results ascertained the shared genetic risk profiles that predisposed individuals to RA and other diseases, which could have implications for identification of molecular targets for drug development, and classification of diseases.
Expression of receptor for advanced glycation end products in sarcoid granulomas
AMERICAN JOURNAL OF RESPIRATORY AND CRITICAL CARE MEDICINE
Authors: Campo, Ilaria; Morbini, Patrizia; Zorzetto, Michele; Tinelli, Carmine; Brunetta, Enrico; Villa, Chiara; Bombieri, Cristina; Cuccia, Mariaclara; Agostini, Carlo; Bozzi, Valeria; Facoetti, Angelica; Ferrarotti, Ilaria; Mazzola, Paola; Scabini, Roberta; Semenzato, Gianpietro; Pignatti, Pier Franco; Pozzi, Ernesto; Luisetti, Maurizio
Abstract
Rationale:The receptor for advanced glycation end products(RAGE) engages a number of ligands implicated in inflammatory processes. The RAGE coding gene maps to the 6p21.32 region, close to the genes DRB1 and BTNL2, which are associated with sarcoidosis. Objectives: We investigated a possible implication of RAGE in sarcoid granulomas. Methods: RAGE and major ligands (N-epsilon-carboxy-methyl-lysine [CML], S100A12, and S100B) expression was investigated by immunostaining of 99 paraffin-embedded biopsies of sarcoid tissues, and expression patterns were determined. Among the three RAGE gene single-nucleoticle polymorphisms investigated, -374 T/A was selected, characterized in terms of transcriptional effect (immunocytochemistry and real-time polymerase chain reaction), and its frequency was determined in DNA extracted from biopsies. Measurements and Results: RAGE, CIVIL, S100A12, and S100B immunoreactivity was observed in all sarcoid granulomas, although at different intensities. The degree of RAGE expression significantly correlated with the degree of S100A12 expression. The -374 TT/AT genotypes, associated with higher RAGE transcriptional activity, were more frequent in the sarcoidosis biopsy group than in control subjects, and the association was confirmed in a second, independent series of 101 patients with sarcoidosis. Conclusions: We showed the association of RAGE and its ligands with sarcoiclosis and suggest that an intrinsic genetic factor could be in part involved in its expression. In Italian patients, the -374 T/A polymorphism seems to be significantly associated with this disease.