To study TNFα and IL-1 cytokine polymorphisms as possible risk and protective factors, define their relative importance and examine these as severity factors in patients with juvenile dermatomyositis (DM).
TNFα and IL-1 cytokine polymorphism and HLA typing were performed in 221 Caucasian patients with juvenile DM and compared to 203 ethnically matched healthy volunteers.
The genotypes TNFα -308AG (odds ratio [OR] 3.6), TNFα -238GG (OR 3.5), and IL-1α+4845TT (OR 2.2) were risk factors, and TNFα -308GG (OR 0.26) as well as TNFα -238AG (OR 0.22) were protective for the development of juvenile DM. Carriage of a single copy of the TNFα -308A (OR 3.8) and IL-1β+3953T (OR 1.7) alleles were risk factors and TNFα -238A (OR 0.29) and IL-1α+4845G (OR 0.46) were protective for juvenile DM. Random Forests classification analysis showed HLA DRB1*03 and TNFα -308A to have highest relative importance as risk factors for juvenile DM compared to the other alleles (Gini scores 100% and 90.7%, respectively). TNFα -308AA (OR 7.3) was a risk factor, and carriage of the TNFα-308G (OR 0.14) and IL1α-889T (OR 0.41) alleles were protective for the development of calcinosis. TNFα-308AA (OR 7.0) was a possible risk factor, and carriage of the TNFα-308G allele (OR 0.14) was protective for the development of ulcerations. None of the studied TNFα, IL-1α and IL-β polymorphisms were associated with disease course, severity at diagnosis, or gender.
TNFα and IL-1 genetic polymorphisms contribute to the development of juvenile DM and may also be indicators of disease severity.