A deletion between the ADAMTS9 and MAGI1 genes was associated with psoriatic arthritis and is unrelated to purely cutaneous psoriasis, according to Dr. Antonio Juliá of Vall d’Hebron Research Institute, Barcelona, and his associates.
Of 165 common copy number variants found in both the psoriatic arthritis (PsA) group and control group, only the ADAMTS9-MAGI1 deletion showed a significant association, with an odds ratio of 1.94. A deletion between the HLA-C and HLA-B genes was initially significant, but the association disappeared after correcting for alleles located at those genes already associated with PsA.
The ADAMTS9-MAGI1 deletion occurred significantly less often in patients with cutaneous psoriasis (PsC) than in PsA patients, and there was no significant difference in deletion frequency between the control group and the PsC group.
“It is possible, however, that once the specific biological mechanisms influenced by this genetic variation are identified, more targeted analysis will reveal association to other PsA phenotypes,” the investigators noted.
Find the full study in Annals of the Rheumatic Diseases (doi:10.1136/annrheumdis-2014-207190)