Familial autoimmunity: maternal parent-of-origin effect in juvenile idiopathic arthritis.

Juvenile idiopathic arthritis (JIA) is an autoimmune (AI) disease characterized by chronic arthritis in children. Children with JIA have increased prevalence of other AI diseases. Furthermore, relatives of children with JIA have been shown to have an increased prevalence of AI diseases. Our objective was to determine if there were differences in the prevalence of AI diseases among maternal and paternal relatives of children with JIA. Information about AI diseases among all living first- and second-degree relatives was collected by structured interviews with families of 121 simplex JIA families, 23 multiplex JIA families, and 45 control families. Overall, the prevalence of AI diseases was significantly increased among maternal second-degree relatives of cases compared to that of maternal second-degree relatives of controls [14% vs. 4.3%; p < 0.001]. The prevalence of AI diseases among mothers of JIA cases was three times that of fathers [32.3% vs. 11.4%; p < 0.0001]. The prevalence of AI diseases among all maternal second-degree relatives of children with JIA was significantly higher than that of all paternal second-degree relatives [14% vs. 7.9%; p < 0.004]. Although additional paternal effects cannot be excluded, together these results demonstrate that maternal relatives of children with JIA have an increased prevalence of autoimmunity compared to paternal relatives, suggesting that there might be a maternal parent-of-origin effect in JIA.

A genome-wide scan for juvenile rheumatoid arthritis in affected sibpair families provides evidence of linkage.

OBJECTIVE: Juvenile rheumatoid arthritis (JRA) represents a heterogeneous group of disorders with a complex genetic component. A genome scan was performed to detect linkage to JRA in 121 families containing 247 affected children in North America (the JRA Affected Sibpair [ASP] Registry). METHODS: Genotype data collected for HLA-DR and 386 microsatellite markers were subjected to multipoint nonparametric linkage analysis. Following analysis of the entire set of families, additional analyses were performed after a priori stratification by disease onset type, age at onset, disease course, and selected HLA-DRB1 alleles. RESULTS: Linkage of JRA to the HLA region was confirmed (logarithm of odds [LOD] score 2.26). Additional evidence supporting linkage of JRA was observed at 1p36 (D1S214; LOD 1.65), 19p13 (D19S216; LOD 1.72), and 20q13 (D20S100; LOD 1.75). For early-onset polyarticular disease, evidence of linkage was found at chromosome 7q11 (D7S502; LOD 3.47). For pauciarticular disease, evidence supporting linkage was observed on chromosome 19p13 (D19S216; LOD 2.98), the same marker that supported linkage to the "JRA" phenotype. Other regions supporting linkage with JRA disease subtype included 20q13, 4q24, 12q24, and Xp11. Stratification of families based on the presence of the HLA-DR8 allele in affected siblings resulted in significant linkage observed at 2p25 (D2S162/D2S305; LOD 6.0). CONCLUSION: These data support the hypothesis that multiple genes, including at least 1 in the HLA region, influence susceptibility to JRA. These findings for JRA are consistent with findings for other autoimmune diseases and support the notion that common genetic regions contribute to an autoimmune phenotype.

Increased prevalence of familial autoimmunity in simplex and multiplex families with juvenile rheumatoid arthritis.

OBJECTIVE: To determine if the prevalence of autoimmunity among relatives of patients with juvenile rheumatoid arthritis (JRA) is greater than that among relatives of healthy volunteer control subjects. METHODS: Interviews were used to obtain histories of the following disorders among living first- and second-degree relatives of 110 patients and 45 controls: alopecia areata, ankylosing spondylitis, dermatomyositis, Graves' disease, Hashimoto thyroiditis, insulin-dependent diabetes mellitus, inflammatory bowel disease, iritis, JRA, multiple sclerosis, psoriasis, RA, systemic lupus erythematosus, and vitiligo. Chi-squares, odds ratios (ORs), and 95% confidence intervals (95% CIs) were calculated. Families of 23 JRA affected sibpairs were interviewed subsequently. RESULTS: There were no significant differences between patients and controls with regard to age, sex, ethnicity, or family size. Patients had 1,228 relatives and controls had 496 relatives. Of all the relatives of the patients, 155 had at least 1 autoimmune disorder, compared with 20 relatives of the controls (12.6% versus 4.0%; OR 3.4 [95% CI 2.1-5.7], P < 0.000001). The prevalence of autoimmunity was increased in first-degree and in second-degree relatives of patients (16.1% and 10.6%, respectively). The prevalence of Hashimoto thyroiditis was significantly higher in the relatives of patients (OR 3.5 [95% CI 1.6-7.9], P = 0.0008). The prevalences of other disorders were not significantly different. JRA affected sibpair families had an increased prevalence of autoimmunity (15.0%). A history of arthritis was found significantly more frequently in the JRA affected sibpair families, but not in the simplex families. CONCLUSION: These data demonstrate that the prevalence of autoimmunity is significantly higher among first- and second-degree relatives of JRA patients. This suggests that clinically different autoimmune phenotypes may share common susceptibility genes, which may act as risk factors for autoimmunity.