The prevalence is estimated to be 1 in 1.6 million, and only about 150 cases have been reported to date.2 One group reported that 4% of male patients with permanent neonatal diabetes were found to have FOXP3 mutations.3 Mutations in FOXP3 lead to a severe deficiency or absence of T regulatory cells leading to multiorgan autoimmunity. This evidence concerns the gene FOXP3 and diabetes mellitus.