Overall, 85 patients (49.1%) with phenotypic features of IPEX from 77 unrelated families (53.8%) had no identifiable mutations in FOXP3. They were designated as IPEX-like and all Italian patients were evaluated for variants by a multiplex panel that included 50 genes involved in known PIDs. This evidence concerns the gene FOXP3 and immune dysregulation-polyendocrinopathy-enteropathy-X-linked syndrome.