The cutoff values for the age at the first visit and serum IgA concentration in the Gini impurity are unknown due to the nature of the random forest method [25], but IgG4-RD often occurs in the elderly [26], and age is presumably used to differentiate IgG4-RD from MCD, as described above [24]. The gene discussed is CD79A; the disease is immunoglobulin G4-related sclerosing disease.