Background Copy-Number Variants (CNV) have been associated to the risk to develop multiple autoimmune diseases.
Objectives Our objective was to identify CNVs associated with the risk to develop Psoriatic Arthritis (PsA) using a genome-wide analysis approach.
Methods A total of 835 PsA patients and 1,498 controls were genotyped for CNVs using the Illumina HumanHap610 BeadChip. The most significant CNV associations with PsA risk were independently tested in a sample of 1,133 PsA patients and 1,831 controls. In order to test for the specificity of the variants with PsA etiology, we also analyzed the association to a cohort of 822 purely cutaneous psoriasis (PsC) patients.
Results A total of 165 common CNVs were identified in the GWAS. We found a highly significant association of an intergenic deletion between ADAMTS9 and MAGI1 genes (p=0.00014). Using the independent patient and control cohort we validated the association between ADAMTS9-MAGI1 deletion and PsA risk (p=0.032). Using next-gen sequencing we characterized the associated deletion. Finally, analyzing the PsC cohort we found a lower frequency of the deletion compared to PsA (p=0.0088) and similar to that of controls (p>0.3).
Conclusions The GWAS for CNVs has identified a new deletion associated with PsA risk and which is also differential from PsC risk.
Disclosure of Interest None declared