FOXP3 and hyperinsulinemic hypoglycemia, familial, 4: Most notably, NR4A family members play redundant roles upstream of Foxp3 to maintain Treg identity and function; deletion of multiple family members in the thymus results in profound Treg deficiency and a severe “Scurfy-like” disease that phenocopies Foxp3-deficient mice (6, 7).