Copy Number Variation of Multiple Genes in SAPHO Syndrome

Objective. SAPHO (synovitis, acne, pustulosis, hyperostosis, osteitis) syndrome is a type of rare chronic aseptic inflammation of unknown etiology. To date, no research to our knowledge has reported copy number variation (CNV) of genes that could affect predisposition to SAPHO syndrome. We investigated the association between CNV profile and SAPHO syndrome. Methods. We used array comparative genomic hybridization (CGH) to screen for CNV in a nuclear family including 2 patients and a healthy control. We then validated the copy numbers of candidate genes found in the array CGH assay and other candidate genes by TaqMan real-time PCR in 360 case and control samples. Results. Ten regions from 8 chromosomes were found to have abnormal gene copies in the nuclear family, so the CNV of candidate genes (ADAM5, CSF2RA, IL3RA, and 9 other genes) were tested by TaqMan PCR. Significant copy number loss of CSF2RA (p = 0.000) and NOD2 (p = 0.005), and significant copy number gain of MEGF6 (p = 0.002) and ADAM5 (p = 0.000) were seen in patients with SAPHO compared with controls at the a = 0.05 level. There were no differences in the other 8 candidate genes between patient and control samples (p > 0.05). Conclusion. Our study established the first association between CNV in CSF2RA, NOD2, MEGF6, and ADAM5 and SAPHO syndrome. These findings may offer insight into the pathogenesis of SAPHO and provide the basis for improved diagnosis and treatment.