U1 and Sacroiliac arthritis: One of control subjects, included in the normal group (patient G, Table 4), was being monitored for sensitive polineuropathy, unilateral sacroiliitis (HLA B27 absent), positive titers of RF, antinuclear, anti-U1 RNP and anti-CCP antibodies, with no signs and symptoms of arthritis, both at the time of the study and in her medical history.