IPEX Syndrome with Normal FOXP3 Protein Expression in Treg Cells in an Infant Presenting with Intractable Diarrhea as aSingle Symptom

IPEX (immune dysregulation-polyendocrinopathy-enteropathy-X-linked) syndrome is a rare, potentially fatal multisystemdisorder caused by mutations in theFOXP3gene. *is can lead to quantitative or functional deficiency of regulatory T cells (Treg),thereby affecting their immune-suppressive actions which can in turn cause autoimmune and inflammatory disorders. Wedescribe an infant with IPEX syndrome with unremarkable maternal family history whose only presentations were severe diarrheaand malnutrition. *e patient had a normal percentage of Treg cells and FOXP3 protein expression, but further testing revealed ahemizygous missense mutation in theFOXP3gene. IPEX syndrome should be considered in young children even if severeintractable diarrhea is the only symptom with no other autoimmune manifestations. Sequencing of theFOXP3gene should alwaysbe considered for accurate diagnosis to look for mutations even in the face of normal FOXP3 protein expression in the Treg cell.