CD4 and systemic lupus erythematosus: Monogenic lupus were distinguished from other familial cases by an even younger age at presentation (6 y vs 19 y, OR = 0.82, P = 2.13 × 10−3), non-biased male-to-female ratio (P = 0.077) and expansion of exhausted CD4+ T cells (CD4+CD45RA+PD-1+) (P = 1.7 × 10−4).