Neutrophils are key immune cells for oral health, and neutrophil deficiency or dysfunction often result in periodontal disease.[24] It has been recognized that patients with CyN often exhibit an early onset of severe periodontitis.[25–27] Conversely, patients with SCN that harbor mutations in the ELANE gene present with more severe periodontal diseases as compared with patients with HAX1 mutations or other unknown mutations.[18] Our patient also presented with severe periodontitis. This evidence concerns the gene HAX1 and severe congenital neutropenia.