GUSB and Whipple disease: (A) Total RNA extracted from healthy unrelated controls (n = 7; IRF4 WT/WT), patients diagnosed with Whipple’s disease (n = 25; WT/WT for all coding exons of IRF4) not related to this kindred, healthy homozygous WT relatives (n = 4, IRF4 WT/WT), patients with monoallelic IRF4 mutations (n = 2; IRF4 WT/R98W) and asymptomatic heterozygous relatives with monoallelic IRF4 mutations (n = 2; IRF4 WT/R98W) was subjected to RT-qPCR for total IRF4. Data are displayed as 2-ΔΔCt after normalization according to endogenous GUSB control gene expression (ΔCt) and the mean of controls (ΔΔCt).