Autoimmune/immune rheumatic diseases in family members of children with enthesitis related arthritis and other categories of juvenile idiopathic arthritis: a study from India

Familial aggregation of autoimmune/inflammatory rheumatic diseases suggests a shared genetic basis for autoimmunity. Data on familial autoimmune/inflammatory rheumatic diseases is limited in JIA.

Accompanying family members of all consecutive patients with JIA attending the clinic during March 2023-May 2024 were asked to participate in the study. Those consenting were interviewed about the history of autoimmune/immune rheumatic diseases among the first- and second-degree relatives, with the help of a questionnaire (validated with medical records or telephonic interviews with relatives). In addition, family members of 71 healthy children served as controls.

8244 relatives of 361 patients with JIA and 1033 relatives of 71 healthy controls were included in the study. Among 361 JIA patients (267 ERA, 24 systemic onset, 44 polyarticular, 12 oligoarticular and 14 psoriatic arthritis) 144 (39.8%) had at least one family member with autoimmune/immune rhematic diseases. In families of children with ERA, Spondyloarthropathy & JIA were the common disease in family while in non-ERA JIA, hypothyroidism and RA were common. First degree relatives had higher prevalence as compared to second degree relatives of patients (130/1639 versus 97/4421; p < 0.05). 2.5% maternal relatives of patients had disease as opposed to 1.9% paternal relatives of patients (p < 0.001). The risk ratio among relatives of JIA patients was 1.22, while the sibling risk ratio was 5.91.

Nearly 40% of JIA patients had familial autoimmune/immune rhematic diseases. While in ERA there was paternal parent of origin effect for SpA in non-ERA there was maternal parent of origin for autoimmune diseases.