This intriguing cell population is increased in systemic lupus erythematosus patients [42], being its nature under discussion since some authors suggested that these T cells were mostly FoxP3+ CD25- non-Treg [43], whereas others have proposed that these cells were dysfunctional Treg which suppressed T cell proliferation but not IFN-γ production in vitro [44]. The gene discussed is FOXP3; the disease is systemic lupus erythematosus.