IPEX syndrome

Immunodysregulation polyendocrinopathy enteropathy X-linked syndrome (IPEX syndrome) is a rare autoimmune disease. It is one of the autoimmune polyendocrine syndromes. Most often, IPEX presents with autoimmune enteropathy, dermatitis (eczema), and autoimmune endocrinopathy (most often Type 1 diabetes), but other presentations exist.

IPEX is caused by mutations in the gene FOXP3, which encodes transcription factor forkhead box P3 (FOXP3). FOXP3 is widely considered to be the master regulator of the regulatory T cell (Treg) lineage. FOXP3 mutation can lead to the dysfunction of CD4⁺ Tregs. In healthy people, Tregs maintain immune homeostasis. When there is a deleterious FOXP3 mutation, Tregs do not function properly and cause autoimmunity.

IPEX onset usually happens in infancy. If left untreated, it is often fatal by the age of 2 or 3. A bone marrow transplant is generally considered the best treatment option. IPEX exclusively affects males and is inherited in an X-linked recessive manner; female carriers of pathogenic FOXP3 mutations do not have symptoms and no female cases are known.