Abstract: Objective To identify the specifically expressed genes in psoriatic lesions by cDNA-representational difference analysis(cDNA-RDA).Methods The total RNA from psoriatic lesions and normal skin was extracted with modified single-step method of RNA isolation by acid guanidinium thiocyanate-phenol-chloroform extraction. mRNA was converted to cDNA. Then cDNA-RDA was employed with a PCR-coupled subtractive approach. Only psoriatic cDNA which contained appropriate adaptors could be amplified. Results The high quality and abundance of mRNA from both lesions and normal skin were demonstrated by 1% agarose gel electrophoresis and autoradiography.After double amplification,the PCR products showed 5 distinctive bands on 1% agarose gel ranged from 100 to 600 bp. Conclusions Our experiment demonstrates that differentially expressed genes might present in psoriatic lesions in comparison with that in normal skin. cDNA-RDA is a highly efficient method for identification of such differentially expressed genes.

Key words: Psoriasis, Polymerase chain reaction, Subtractive hybridization