They have also been reported in patients with immunodysregulation polyendocrinopathy enteropathy X-linked (IPEX) due to deleterious variants of FOXP3, and combined immunodeficiency due to biallelic hypomorphic RAG1 or RAG2 variants (37–42). Here, FOXP3 is linked to immune dysregulation-polyendocrinopathy-enteropathy-X-linked syndrome.