Objective    To compare the gene expression difference between human ankylosing spondylitis (AS) and normal sacroiliac joint tissues

and to screen AS-associated genes via cDNA microarray.     Methods    Three AS samples in active phase were collected and used as a test group

and a fracture sample was used as a control group. Total RNA was isolated from synovial and paravertebral tissues of both AS and normal sacroiliac joints

and used to construct hybridization probes. The probes were hybridized to cDNA microarray GeneChip Human Genome U133 Plus 2.0 Array. The differentially expressed genes in AS tissues were identified. Finally

semi-quantitative RT-PCR was used to confirm the results of the cDNA microarray.     Results    Compared with the normal tissue sample

237 differentially expressed genes were detected in AS group

including 91 up-regulated and 78 down-regulated known genes. The semi-quantitative RT-PCR test revealed that the expression patterns of 20 candidate differentially expressed genes were consistent with the results of cDNA microarray.     Conclusion    A number of AS-associated differentially expressed genes are detected

and the present study will be helpful to unveil the molecular mechanism of AS.