Two longitudinal studies, one using limiting dilution analysis of the frequency of PLP41–58- and PLP184–209-reactive T cells over an 18 month period in 5 relapsing-remitting MS patients and 4 healthy controls [100] and the other testing the response to whole human PLP in 7 MS patients and 2 healthy controls by IFN-γ ELISPOT assays [97], have been reported. The gene discussed is IFNG; the disease is relapsing-remitting multiple sclerosis.