Generalized aggressive periodontitis (GAP) is an uncommon periodontal disease characterized by rapid destruction of periodontal tissues, leading to severe attachment and bone loss. The onset of the disease can be as early as at the primary dentition, and GAP is sometimes found to be an oral manifestation of systemic problems. Early diagnosis and management are imperative to control the disease progress, preserve primary teeth, and prevent further damages to their permanent successors. In this report, we presented a case of an 8-year-old boy showing generalized periodontal bone loss with an underlying disease of neutropenia. He also had concomitant hypo-hyperdontia, a rare numeric dental abnormality with simultaneous occurrence of missing and supernumerary teeth.