USP18 and fetal growth restriction: Except for AGS, USP18 deficiency, and probably other Type 1 interferonopathies, in which most precocious manifestations mimic a TORCH syndrome, in the IEI diseases addressed here (HLH, IPEX, defects of IL-2 receptor β chain, X-linked CGD, NOMID/CINCA), the intrauterine manifestations are quite similar, presenting mainly as hydrops and IUGR, which leads to fetal losses, stillbirths, and prematurity (15, 16).