Deficiency in ELF4, X-linked (DEX) is a newly identified monogenic autoinflammatory disease. Most reported cases are male, leading to the recognition of DEX being primarily limited to male patients. Here we described 3 pediatric female patients with DEX from 3 unrelated families, who are all heterozygous for ELF4 mutations (c.320_c.321insA, c.329delA and c.685 A >
G). Similar to reported male DEX patients, the main clinical features include recurring oral ulcers, abdominal pain and diarrhea with colonoscopy showing ulcers in the colon. Meanwhile, novel and effective treatment strategies, such as the use of the biologic vedolizumab and exclusive enteral nutrition (EEN), have provided additional options for the treatment of DEX. Finally, we observed skewed X chromosome inactivation patterns in all three female patients, with over-inactivation of the X chromosome carrying the wild-type allele confirmed in two of them.