Juvenile idiopathic polyarticular arthritis and IgA deficiency in the 22q11 deletion syndrome

Five patients with the 22q11 deletion syndrome (velocardiofacial syndrome) developed chronic inflammatory polyarticular arthritis. These new cases add to 8 previously reported and confirm the association. The arthritis in all cases was moderate to severe, but at least partially responsive to methotr exate and/or corticosteroids, and was clinically indistinguishable from juv enile idiopathic arthritis (JIA). Analysis of the total 13 patients indicat es that 2 are rheumatoid factor positive, 6 are antinuclear antibody positi ve, 5 have subtle T cell deficiencies, and 6 have hypergammaglobulinemia. O f particular interest is the occurrence of IgA deficiency in 4 patients, in cluding 2 from our own series. Although IgA deficiency is seen in both JIA (2-4%) and 22q11 deletion syndrome (2-4%), the prevalence of low IgA in thi s series (31%) is much greater than expected. This phenomenon and the true association of inflammatory arthritis and a chromosome deletion disorder pr ovides further evidence of important genetic factors in the pathogenesis of JIA.