To evaluate the occurrence of autoimmune diseases in first-degree relatives of children with juvenile idiopathic arthritis (JIA) and to compare the figures with published population data.
Families of the 362 children with recently diagnosed JIA admitted to Rheumatism Foundation Hospital, Finland, from 1996 to 2001 were contacted by questionnaires regarding autoimmune diseases in family members. Data were collected on type 1 diabetes, coeliac disease, multiple sclerosis and chronic arthritis, consisting mainly of JIA, rheumatoid arthritis, spondyloarthropathy or psoriatic arthritis.
In all, 21.4% of the 355 families with a patient with JIA had members with type 1 diabetes, coeliac disease, multiple sclerosis or chronic arthritis. Thirty-three mothers and 23 fathers had type 1 diabetes, coeliac disease, multiple sclerosis or chronic arthritis in 15.2% (95% CI 11.6-19.4) of the families, and 23 mothers and 15 fathers had chronic arthritis in 10.7% (95% CI 7.7-14.5) of the families. When compared with available research data, the prevalences of rheumatoid arthritis, spondyloarthropathy, psoriatic arthritis, paediatric type 1 diabetes and JIA (in siblings) were increased in JIA families. Coeliac disease was as prevalent as in the population.
Autoimmune diseases cluster in families with a child with JIA.