This study aimed to identify polymorphic variants of the Periostin gene associated with disease severity and clinical course in children with juvenile idiopathic arthritis.
DNA genotyping of 7 single-nucleotide polymorphisms within the periostin gene was performed in 117 patients and their parents and in 102 control samples. Our patients were divided in the following 4 disease categories: 1) persistent oligoarthritis; 2) extended oligoarthritis; 3) polyarthritis; 4) systemic arthritis. Quantitative association analysis was performed in order to test for association between the 7 genetic variants and 18 selected clinical traits.
A harmful association was observed between the minor allele of rs17197936 and 2 clinical traits, count of joints with active arthritis and count of joints with pain on motion/tenderness, in patients with extended oligoarthritis. Furthermore, the haplotype represented by the minor allele variants of rs3829364, rs6750 and rs9547951 showed an unfavourable association with the above 2 traits plus the following 3 in the whole patient group: juvenile arthritis damage index articular score, childhood health assessment questionnaire score and disease duration.
These associations suggest that the variants involved can be regarded as genetic factors influencing some phenotypic aspects of juvenile idiopathic arthritis. Genotyping of this gene may represent a useful tool to identify patients who are at greatest risk of experiencing a poorer long-term outcome.