USP18 is a key negative regulator of type I IFN signaling, and its deficiency represents the genetic disorder of PTS and specifically pseudo-TORCH syndrome 2 (PTORCH2) that is caused by dysregulation of the response to type I IFN, which is represented by early-onset intracranial calcifications, thrombocytopenia, and other features of the pseudo-TORCH phenotype [8, 11]. Here, USP18 is linked to calcification.