Circulating long noncoding RNA growth arrest-specific transcript 5 as a diagnostic marker and indicator of degree of severity in plaque psoriasis

Background: The current study aims at evaluating the role of circulating or cell-free long noncoding ribonucleic acid (lncRNA) growth arrest-specific 5 (GAS5) in plaque psoriasis and at investigating its relationship with the presented clinical data. Methods: This case-control study was conducted on 180 subjects, divided into two main categories as follows: 90 cases with plaque psoriasis and 90 age- and sex-matched healthy controls. Full history taking, thorough general examination, and full dermatological examination with determination of number and site of lesions were performed. Disease severity was assessed by Psoriasis Area Severity Index (PASI) score. Relative quantification of the expression level of cell-free lncRNA (GAS5) was performed using real-time polymerase chain reaction (RT-PCR) technique. Results: There was significant increase of GAS5 expression level in cases when compared with controls (U = 719.0, P < 0.001). Indeed, there was significant positive correlation between GAS5 and PASI score (r = 0.0.668, P < 0.001). Receiver operating characteristic (ROC) curve showed that GAS5 could identify patients from controls: GAS5 at a cut-off value ≥0.31 provides a sensitivity of 95.56% and a specificity of 82.22%; at a cut-off value ≥0.75, it can differentiate between mild and moderate cases, at a sensitivity of 77.78% and a specificity of 91.43%; at a cut-off value ≥1.61, it can discriminate between moderate and severe cases, with a sensitivity of 71.43% and a specificity of 74.07%. Conclusion: lncRNA GAS5 expression could be considered as a diagnostic marker of plaque psoriasis and indicator of its severity.