As part of the methods for assessing interferon-related biomarkers in Aicardi-Goutières syndrome (AGS), 6 interferon stimulated genes (ISGs) were tested with 9 other ISGs and were selected for this experiment because they were highly expressed and easily differentiated from the controls. The median fold change of the ISGs compared to the median fold change of the control samples was used to construct an interferon score. The experiment included running the samples, the six ISGs and two internal controls, through the RT-PCR to measure the fold change of each ISG. The internal controls were housekeeping genes: HPRT1 and 18S.