Variable Clinical Phenotypes and Relation of Interferon Signature with Disease Activity in ADA2 Deficiency

Objective. An upregulation of type I interferon (IFN) stimulated genes [IFN score (IS)] was described in patients with adenosine deaminase 2 deficiency (DADA2). We describe the clinical course of 5 such patients and the role of IS as a marker of disease activity and severity. Methods. Expression levels of IS were determined by quantitative real-time PCR. Results. Five white patients were identified as carrying CECR1 mutations. The IS before treatment was elevated in 4 out of 5 patients and decreased after treatment. Conclusion. Our data confirm the high variability of DADA2 and suggest type I IS as a biomarker of disease activity.