Abstract: Primary hyperparathyroidism (PHPT) is relatively rare in individuals before adulthood. Among juvenile patients, hereditary PHPT accounts for a significant proportion. Specifically, infant and toddler patients often carry gene mutations related to the calcium-sensing receptor signaling pathway, whereas children and adolescent patients predominantly exhibit mutations in genes associated with cell proliferation. Notably, PHPT in infants, children, and adolescents differs significantly from that in adult patients in terms of genetic background, clinical manifestations, treatment strategies, and prognosis. This article aims to systematically summarize the genetic characteristics and clinical features of juvenile-onset PHPT to enhance the understanding of this disease.