Arthritis, Juvenile/genetics; Arthritis, Rheumatoid/genetics; Genetic Predisposition to Disease/genetics; Adaptor Proteins, Signal Transducing; Adult; Age of Onset; Aged; Alleles; Antigens, CD/genetics; Antigens, Differentiation/genetics; CTLA-4 Antigen; Child; DNA/genetics; Female; Gene Frequency; Genotype; Germany; HLA-DR Antigens/genetics; HLA-DRB1 Chains; Histocompatibility Antigens Class II/genetics; Humans; Interferon-gamma/genetics; Leukocyte Common Antigens/genetics; Macrophage Migration-Inhibitory Factors/genetics; Male; Microsatellite Repeats/genetics; Middle Aged; Polymorphism, Genetic; Polymorphism, Single-Stranded Conformational; Receptors, Tumor Necrosis Factor/genetics; Receptors, Tumor Necrosis Factor, Type I; Receptors, Tumor Necrosis Factor, Type II; Tumor Necrosis Factor-alpha/genetics