In the previous Grand Challenge program on Primary Immune Deficiencies, the mRNA based 'interferon score' test was developed and successfully implemented in the diagnostic workup of a small cohort of patients in a research setting. This validation project, PID 2.0, aims to further develop the ‘interferon score' into a clinical-grade diagnostic test and incorporate this tool into the clinical assessment for patients suspected of dysregulated IFN signaling. The diagnostic utility of this novel test will be investigated across different patients with distinct disease presentations, both on a national and international level. This advancement seeks to improve early diagnosis and guide targeted treatment strategies to enhance patient outcomes.